TY  - JOUR
AU  - Marjanović, V.
AU  - Lazarević, Slavica
AU  - Janković-Častvan, Ivona
AU  - Potkonjak, Branislav
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1916
AB  - Natural and acid-activated sepiolite samples were functionalized with (3-Mercaptopropyl)trimethoxysilane. By X-ray powder diffraction, Fourier transform infrared spectroscopy, and differential thermal analysis it was shown that functionalization of sepiolites by grafting silane reagents occurs mainly on the surface, whereby their crystalline structure remained unchanged. The efficiency of the adsorbents in Cr(VI) removal from aqueous solutions follows the order: functionalized acid-activated sepiolite  gt  functionalized natural sepiolite  gt  acid-activated sepiolite  gt  natural sepiolite. As the number of silanol groups on the sepiolite surface increased during the acid activation, the silane functionalization increased and this led to an increase in Cr(VI) adsorption. The adsorption capacity strongly depended on the pH of the solution from which the adsorption occurred. Maximum Cr(VI) removal was ca. 8.0 mg Cr(VI) per g of functionalized acid-activated sepiolite at initial pH 3, when the pH of solution reached 4.7, and ca. 2.7 mg Cr(VI) per g of functionalized natural sepiolite at initial pH 2, when the pH of the solution reached 2.5. Cr(VI) removal by the functionalized sepiolites was mainly attributed to electrostatic attraction between the protonated mercapto groups and the negatively charged Cr(VI) species. The sorption isotherms showed that Cr(VI) removal by both functionalized sepiolites for all initial investigated solution pH values is well described using the Dubinin-Radushkevich model. The thermodynamic data suggest spontaneity of the major physical adsorption process at 298 K.
PB  - Elsevier Science Sa, Lausanne
T2  - Chemical Engineering Journal
T1  - Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites
EP  - 206
IS  - 1
SP  - 198
VL  - 166
DO  - 10.1016/j.cej.2010.10.062
ER  - 

@article{
author = "Marjanović, V. and Lazarević, Slavica and Janković-Častvan, Ivona and Potkonjak, Branislav and Janaćković, Đorđe and Petrović, Rada",
year = "2011",
abstract = "Natural and acid-activated sepiolite samples were functionalized with (3-Mercaptopropyl)trimethoxysilane. By X-ray powder diffraction, Fourier transform infrared spectroscopy, and differential thermal analysis it was shown that functionalization of sepiolites by grafting silane reagents occurs mainly on the surface, whereby their crystalline structure remained unchanged. The efficiency of the adsorbents in Cr(VI) removal from aqueous solutions follows the order: functionalized acid-activated sepiolite  gt  functionalized natural sepiolite  gt  acid-activated sepiolite  gt  natural sepiolite. As the number of silanol groups on the sepiolite surface increased during the acid activation, the silane functionalization increased and this led to an increase in Cr(VI) adsorption. The adsorption capacity strongly depended on the pH of the solution from which the adsorption occurred. Maximum Cr(VI) removal was ca. 8.0 mg Cr(VI) per g of functionalized acid-activated sepiolite at initial pH 3, when the pH of solution reached 4.7, and ca. 2.7 mg Cr(VI) per g of functionalized natural sepiolite at initial pH 2, when the pH of the solution reached 2.5. Cr(VI) removal by the functionalized sepiolites was mainly attributed to electrostatic attraction between the protonated mercapto groups and the negatively charged Cr(VI) species. The sorption isotherms showed that Cr(VI) removal by both functionalized sepiolites for all initial investigated solution pH values is well described using the Dubinin-Radushkevich model. The thermodynamic data suggest spontaneity of the major physical adsorption process at 298 K.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Chemical Engineering Journal",
title = "Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites",
pages = "206-198",
number = "1",
volume = "166",
doi = "10.1016/j.cej.2010.10.062"
}

Marjanović, V., Lazarević, S., Janković-Častvan, I., Potkonjak, B., Janaćković, Đ.,& Petrović, R.. (2011). Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites. in Chemical Engineering Journal
Elsevier Science Sa, Lausanne., 166(1), 198-206.
https://doi.org/10.1016/j.cej.2010.10.062

Marjanović V, Lazarević S, Janković-Častvan I, Potkonjak B, Janaćković Đ, Petrović R. Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites. in Chemical Engineering Journal. 2011;166(1):198-206.
doi:10.1016/j.cej.2010.10.062 .

Marjanović, V., Lazarević, Slavica, Janković-Častvan, Ivona, Potkonjak, Branislav, Janaćković, Đorđe, Petrović, Rada, "Chromium (VI) removal from aqueous solutions using mercaptosilane functionalized sepiolites" in Chemical Engineering Journal, 166, no. 1 (2011):198-206,
https://doi.org/10.1016/j.cej.2010.10.062 . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Jančić-Heinemann, Radmila
AU  - Balać, Igor
AU  - Jokić, Bojan
AU  - Putić, Slaviša
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1906
AB  - In this study, the influence of the shape and size of the pores on the mechanical properties of the obtained porous HAP-based bioceramics was investigated. The porous HAP-based bioceramics were obtained starting from spherical calcium hydroxyapatite powder, obtained by hydrothermal syntheses. The number of shapeless inter-agglomerate pores decreased and amount of spherical intra-agglomerate pores increased on increasing the sintering temperature from 1100 degrees C to 1250 degrees C. The shape of pores also changed with thermal treatment of specimens; the small pores remained spherical while the larger pores became more spherical in shape, as was proved by image analysis. A three-dimensional, finite element unit cell model was applied to evaluate the influence of pore shape on the mechanical strength of HAP ceramics. By analyzing the effect of. the shape of pores to the fracture toughness of sintered porous HAP bioceramics, it was observed that the more spherical the pores were, the tougher became the bioceramics. After sintering at 1250 degrees C for 2 h, measured toughness was 1.31 MPa m(1/2), which is a relatively high value for this type of bioceramics.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics
EP  - 479
IS  - 2
SP  - 471
VL  - 37
DO  - 10.1016/j.ceramint.2010.09.014
ER  - 

@article{
author = "Veljović, Đorđe and Jančić-Heinemann, Radmila and Balać, Igor and Jokić, Bojan and Putić, Slaviša and Petrović, Rada and Janaćković, Đorđe",
year = "2011",
abstract = "In this study, the influence of the shape and size of the pores on the mechanical properties of the obtained porous HAP-based bioceramics was investigated. The porous HAP-based bioceramics were obtained starting from spherical calcium hydroxyapatite powder, obtained by hydrothermal syntheses. The number of shapeless inter-agglomerate pores decreased and amount of spherical intra-agglomerate pores increased on increasing the sintering temperature from 1100 degrees C to 1250 degrees C. The shape of pores also changed with thermal treatment of specimens; the small pores remained spherical while the larger pores became more spherical in shape, as was proved by image analysis. A three-dimensional, finite element unit cell model was applied to evaluate the influence of pore shape on the mechanical strength of HAP ceramics. By analyzing the effect of. the shape of pores to the fracture toughness of sintered porous HAP bioceramics, it was observed that the more spherical the pores were, the tougher became the bioceramics. After sintering at 1250 degrees C for 2 h, measured toughness was 1.31 MPa m(1/2), which is a relatively high value for this type of bioceramics.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics",
pages = "479-471",
number = "2",
volume = "37",
doi = "10.1016/j.ceramint.2010.09.014"
}

Veljović, Đ., Jančić-Heinemann, R., Balać, I., Jokić, B., Putić, S., Petrović, R.,& Janaćković, Đ.. (2011). The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics. in Ceramics International
Elsevier Sci Ltd, Oxford., 37(2), 471-479.
https://doi.org/10.1016/j.ceramint.2010.09.014

Veljović Đ, Jančić-Heinemann R, Balać I, Jokić B, Putić S, Petrović R, Janaćković Đ. The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics. in Ceramics International. 2011;37(2):471-479.
doi:10.1016/j.ceramint.2010.09.014 .

Veljović, Đorđe, Jančić-Heinemann, Radmila, Balać, Igor, Jokić, Bojan, Putić, Slaviša, Petrović, Rada, Janaćković, Đorđe, "The effect of the shape and size of the pores on the mechanical properties of porous HAP-based bioceramics" in Ceramics International, 37, no. 2 (2011):471-479,
https://doi.org/10.1016/j.ceramint.2010.09.014 . .

TY  - JOUR
AU  - Jokić, Bojan
AU  - Mitrić, Miodrag
AU  - Radmilović, Velimir R.
AU  - Drmanić, Saša
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2011
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1913
AB  - High temperature hydrothermal syntheses, using calcium nitrate tetrahydrate, sodium dihydrogen phosphate and urea as precursors, and characterization of hydroxyapatite (HAp) whiskers are reported herein. The morphology and chemical composition of the crystals from a monetite to a hydroxyapatite phase were controlled by varying the starting concentrations of the precursors and the solution pH through the amount of urea that is decomposed during heating. X-ray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to investigate the products of the syntheses in order to find the optimum reaction conditions for obtaining the desired morphology and phase composition. Different morphologies ranging from single crystals of monetite through rods and plates of hydroxyapatite with different size distribution to whisker-like single hydroxyapatite crystal were achieved by simply varying the starting concentration of urea. Structural refinement of the hydroxyapatite whiskers confirmed a strong preferential orientation along the c-axis direction of the hexagonal crystal structure, which was significantly different from the usually observed random crystal orientation. TEM and SEM analysis of the apatite whiskers confirmed single crystal structure with the a c-axis orientation parallel to the long axis of the whiskers, with sizes up to 150 mu m in length, 10 mu m in width and with a thickness of about 300 nm, that grew from the same centre of nucleation, forming flaky-like particles.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Synthesis and characterization of monetite and hydroxyapatite whiskers obtained by a hydrothermal method
EP  - 173
IS  - 1
SP  - 167
VL  - 37
DO  - 10.1016/j.ceramint.2010.08.032
ER  - 

@article{
author = "Jokić, Bojan and Mitrić, Miodrag and Radmilović, Velimir R. and Drmanić, Saša and Petrović, Rada and Janaćković, Đorđe",
year = "2011",
abstract = "High temperature hydrothermal syntheses, using calcium nitrate tetrahydrate, sodium dihydrogen phosphate and urea as precursors, and characterization of hydroxyapatite (HAp) whiskers are reported herein. The morphology and chemical composition of the crystals from a monetite to a hydroxyapatite phase were controlled by varying the starting concentrations of the precursors and the solution pH through the amount of urea that is decomposed during heating. X-ray diffraction (XRD) analysis, infrared spectroscopy (IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) were used to investigate the products of the syntheses in order to find the optimum reaction conditions for obtaining the desired morphology and phase composition. Different morphologies ranging from single crystals of monetite through rods and plates of hydroxyapatite with different size distribution to whisker-like single hydroxyapatite crystal were achieved by simply varying the starting concentration of urea. Structural refinement of the hydroxyapatite whiskers confirmed a strong preferential orientation along the c-axis direction of the hexagonal crystal structure, which was significantly different from the usually observed random crystal orientation. TEM and SEM analysis of the apatite whiskers confirmed single crystal structure with the a c-axis orientation parallel to the long axis of the whiskers, with sizes up to 150 mu m in length, 10 mu m in width and with a thickness of about 300 nm, that grew from the same centre of nucleation, forming flaky-like particles.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Synthesis and characterization of monetite and hydroxyapatite whiskers obtained by a hydrothermal method",
pages = "173-167",
number = "1",
volume = "37",
doi = "10.1016/j.ceramint.2010.08.032"
}

Jokić, B., Mitrić, M., Radmilović, V. R., Drmanić, S., Petrović, R.,& Janaćković, Đ.. (2011). Synthesis and characterization of monetite and hydroxyapatite whiskers obtained by a hydrothermal method. in Ceramics International
Elsevier Sci Ltd, Oxford., 37(1), 167-173.
https://doi.org/10.1016/j.ceramint.2010.08.032

Jokić B, Mitrić M, Radmilović VR, Drmanić S, Petrović R, Janaćković Đ. Synthesis and characterization of monetite and hydroxyapatite whiskers obtained by a hydrothermal method. in Ceramics International. 2011;37(1):167-173.
doi:10.1016/j.ceramint.2010.08.032 .

Jokić, Bojan, Mitrić, Miodrag, Radmilović, Velimir R., Drmanić, Saša, Petrović, Rada, Janaćković, Đorđe, "Synthesis and characterization of monetite and hydroxyapatite whiskers obtained by a hydrothermal method" in Ceramics International, 37, no. 1 (2011):167-173,
https://doi.org/10.1016/j.ceramint.2010.08.032 . .

TY  - JOUR
AU  - Lazarević, Slavica
AU  - Janković-Častvan, Ivona
AU  - Đokić, Veljko
AU  - Radovanović, Željko
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1717
AB  - Sepiolite was used for the synthesis of the sepiolite-iron oxide system to obtain a sorbent suitable for the removal of Ni2+ from aqueous solution. The modified material, Fe-sepiolite, was characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential thermal/thermogravimetric analysis, and point of zero charge (pH(pzc)) determination. The sorption experiments were performed as a function of the initial metal concentration, equilibration time, and temperature using the batch method. The Fe-sepiolite had a higher sorption capacity than the natural sepiolite sample due to a higher specific sorption and a higher ion exchange with Mg2+ ions from the sepiolite surface. Thermodynamic parameters, such as enthalpy, Gibbs energy, and entropy, were calculated from the temperature-dependent sorption isotherms, and these values showed that the sorption of Ni2+ onto sepiolites was endothermic. Pseudo-second-order kinetic models provide the best correlation of the experimental kinetic data.
PB  - Amer Chemical Soc, Washington
T2  - Journal of Chemical and Engineering Data
T1  - Iron-Modified Sepiolite for Ni2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study
EP  - 5689
IS  - 12
SP  - 5681
VL  - 55
DO  - 10.1021/je100639k
ER  - 

@article{
author = "Lazarević, Slavica and Janković-Častvan, Ivona and Đokić, Veljko and Radovanović, Željko and Janaćković, Đorđe and Petrović, Rada",
year = "2010",
abstract = "Sepiolite was used for the synthesis of the sepiolite-iron oxide system to obtain a sorbent suitable for the removal of Ni2+ from aqueous solution. The modified material, Fe-sepiolite, was characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, differential thermal/thermogravimetric analysis, and point of zero charge (pH(pzc)) determination. The sorption experiments were performed as a function of the initial metal concentration, equilibration time, and temperature using the batch method. The Fe-sepiolite had a higher sorption capacity than the natural sepiolite sample due to a higher specific sorption and a higher ion exchange with Mg2+ ions from the sepiolite surface. Thermodynamic parameters, such as enthalpy, Gibbs energy, and entropy, were calculated from the temperature-dependent sorption isotherms, and these values showed that the sorption of Ni2+ onto sepiolites was endothermic. Pseudo-second-order kinetic models provide the best correlation of the experimental kinetic data.",
publisher = "Amer Chemical Soc, Washington",
journal = "Journal of Chemical and Engineering Data",
title = "Iron-Modified Sepiolite for Ni2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study",
pages = "5689-5681",
number = "12",
volume = "55",
doi = "10.1021/je100639k"
}

Lazarević, S., Janković-Častvan, I., Đokić, V., Radovanović, Ž., Janaćković, Đ.,& Petrović, R.. (2010). Iron-Modified Sepiolite for Ni2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study. in Journal of Chemical and Engineering Data
Amer Chemical Soc, Washington., 55(12), 5681-5689.
https://doi.org/10.1021/je100639k

Lazarević S, Janković-Častvan I, Đokić V, Radovanović Ž, Janaćković Đ, Petrović R. Iron-Modified Sepiolite for Ni2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study. in Journal of Chemical and Engineering Data. 2010;55(12):5681-5689.
doi:10.1021/je100639k .

Lazarević, Slavica, Janković-Častvan, Ivona, Đokić, Veljko, Radovanović, Željko, Janaćković, Đorđe, Petrović, Rada, "Iron-Modified Sepiolite for Ni2+ Sorption from Aqueous Solution: An Equilibrium, Kinetic, and Thermodynamic Study" in Journal of Chemical and Engineering Data, 55, no. 12 (2010):5681-5689,
https://doi.org/10.1021/je100639k . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Palcevskis, Eriks
AU  - Dindune, Antonija
AU  - Putić, Slaviša
AU  - Balać, Igor
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1703
AB  - Starting from two microspherical agglomerated HAP powders, porous biphasic HAP/TCP bioceramics were obtained by microwave sintering. During the sintering the HAP powders turned into biphasic mixtures, whereby HAP was the dominant crystalline phase in the case of the sample with the higher Ca/P ratio (HAP1) while alpha-TCP was the dominant crystalline phase in the sample with lower Ca/P ratio (HAP2). The porous microstructures of the obtained bioceramics were characterized by spherical intra-agglomerate pores and shapeless inter-agglomerate pores. The fracture toughness of the HAP1 and HAP2 samples microwave sintered at 1200 A degrees C for 15 min were 1.25 MPa m(1/2). The phase composition of the obtained bioceramics only had a minor effect on the indentation fracture toughness compared to a unique microstructure consisting of spherical intra-agglomerate pores with strong bonds between the spherical agglomerates. Cold isostatic pressing at 400 MPa before microwave sintering led to an increase in the fracture toughness of the biphasic HAP/TCP bioceramics to 1.35 MPa m(1/2).
PB  - Springer, New York
T2  - Journal of Materials Science
T1  - Microwave sintering improves the mechanical properties of biphasic calcium phosphates from hydroxyapatite microspheres produced from hydrothermal processing
EP  - 3183
IS  - 12
SP  - 3175
VL  - 45
DO  - 10.1007/s10853-010-4324-8
ER  - 

@article{
author = "Veljović, Đorđe and Palcevskis, Eriks and Dindune, Antonija and Putić, Slaviša and Balać, Igor and Petrović, Rada and Janaćković, Đorđe",
year = "2010",
abstract = "Starting from two microspherical agglomerated HAP powders, porous biphasic HAP/TCP bioceramics were obtained by microwave sintering. During the sintering the HAP powders turned into biphasic mixtures, whereby HAP was the dominant crystalline phase in the case of the sample with the higher Ca/P ratio (HAP1) while alpha-TCP was the dominant crystalline phase in the sample with lower Ca/P ratio (HAP2). The porous microstructures of the obtained bioceramics were characterized by spherical intra-agglomerate pores and shapeless inter-agglomerate pores. The fracture toughness of the HAP1 and HAP2 samples microwave sintered at 1200 A degrees C for 15 min were 1.25 MPa m(1/2). The phase composition of the obtained bioceramics only had a minor effect on the indentation fracture toughness compared to a unique microstructure consisting of spherical intra-agglomerate pores with strong bonds between the spherical agglomerates. Cold isostatic pressing at 400 MPa before microwave sintering led to an increase in the fracture toughness of the biphasic HAP/TCP bioceramics to 1.35 MPa m(1/2).",
publisher = "Springer, New York",
journal = "Journal of Materials Science",
title = "Microwave sintering improves the mechanical properties of biphasic calcium phosphates from hydroxyapatite microspheres produced from hydrothermal processing",
pages = "3183-3175",
number = "12",
volume = "45",
doi = "10.1007/s10853-010-4324-8"
}

Veljović, Đ., Palcevskis, E., Dindune, A., Putić, S., Balać, I., Petrović, R.,& Janaćković, Đ.. (2010). Microwave sintering improves the mechanical properties of biphasic calcium phosphates from hydroxyapatite microspheres produced from hydrothermal processing. in Journal of Materials Science
Springer, New York., 45(12), 3175-3183.
https://doi.org/10.1007/s10853-010-4324-8

Veljović Đ, Palcevskis E, Dindune A, Putić S, Balać I, Petrović R, Janaćković Đ. Microwave sintering improves the mechanical properties of biphasic calcium phosphates from hydroxyapatite microspheres produced from hydrothermal processing. in Journal of Materials Science. 2010;45(12):3175-3183.
doi:10.1007/s10853-010-4324-8 .

Veljović, Đorđe, Palcevskis, Eriks, Dindune, Antonija, Putić, Slaviša, Balać, Igor, Petrović, Rada, Janaćković, Đorđe, "Microwave sintering improves the mechanical properties of biphasic calcium phosphates from hydroxyapatite microspheres produced from hydrothermal processing" in Journal of Materials Science, 45, no. 12 (2010):3175-3183,
https://doi.org/10.1007/s10853-010-4324-8 . .

TY  - THES
AU  - Veljović, Đorđe
PY  - 2010
UR  - http://eteze.bg.ac.rs/application/showtheses?thesesId=949
UR  - https://fedorabg.bg.ac.rs/fedora/get/o:7504/bdef:Content/download
UR  - http://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=37597711
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4599
AB  - Calcium phosphate bioceramics materials based on hydroxyapatite (HAP) and tricalcium phosphate (TCP), due to their chemical composition, excellent biocompatibility, bioactivity and osteoconduction have received considerable attention as suitable bioceramics for the manufacture of osseous implants. Dense nanostructured and controlled porous forms of hydroxyapatite and calcium phosphate are often used as reparation material in maxillofacial, dental and orthopedic surgery. Careful control of phase composition, grain size and shape and size of pores of sintered bioceramic materials in accordance with good mechanical properties can be key issue for a successful implant. A large number of studies were focused on determining the optimal conditions required to obtain dense or controlled porous HAP and HAP/TCP form suitable for incorporation in living bone. The aim of this PhD thesis was to investigate the processing of dense nanostructured pure hydroxyapatite and biphasic HAP/TCP bioceramics by microwave sintering, spark plasma sintering and hot pressing, starting from stoichiometric and calcium deficient nanosized HAP powders, obtained by two modified chemical precipitation syntheses. The effects of the processing conditions on the microstructure, phase composition and mechanical properties of the obtained materials based on HAP and TCP were investigated. The influence of microstructure and phase composition on the fracture toughness and hardness of sintered HAP and HAP/TCP bioceramics was also defined. The influence of the grain size and phase composition on the nanomechanical behaviour of dense nano and microstructured HAP and biphasic HAP/β-TCP bioceramic materials by nanoindentation was also investigated. The results obtained by microwave sintering, spark plasma sintering and hot pressing were compared with those obtained by conventional sintering methods...
AB  - Kalcijum-fosfatni biokeramički materiali na bazi kalcijum-hidroksiapatita (HAP) i trikalcijum-fosfata (TCP), zahvaljujući hemijskom sastavu, biokompatibilnosti, bioaktivnosti i osteokonduktivnosti imaju značajnu ulogu pri izradi koštanih implanta. Guste nanostrukturne i kontrolisano porozne forme biokeramičkih materijala na bazi hidroksiapatita i kalcijum-fosfata imaju veliku primenu u maksiofacialnoj, dentalnoj i ortopedskoj praksi. Pažljiva kontrola faznog sastava, veličine zrna, oblika i dimenzija pora, kao i mehaničkih svojstava sinterovanih biokeramičkih materijala jesu ključni faktori za dobijanje implanata optimalnih svojstava. Danas je ogroman broj istraživanja baziran upravo na definisanju optimalnih uslova procesiranja sa ciljem da se dobiju gusti i kontrolisano porozni biokeramički monofazni kalcijum-hidroksiapatitni i bifazni materijali na bazi HAP i TCP, pogodni za ugradnju u ljudski organizam. Cilj ove doktorske disertacije bio je proučavanje procesa formiranja gustih nanostrukturnih biokeramičkih materijala na bazi kalcijum-hidroksiapatita i kalcijum-fosfata mikrotalasnim sinterovanjem, spark plazma sinterovanjem i toplim presovanjem, polazeći od stehiometrijskih i kalcijum deficitarnih nanočestičnih prahova kalcijum-hidroksiapatita dobijenih modifikovanim precipitacionim sintezama. Ispitan je uticaj svojstava polaznih prahova HAP i parametara procesiranja na mikrostukturne i fazne karakteristike, kao i na mehanička svojstva dobijenih gustih sinterovanih biokeramičkih materijala. Definisan je uticaj mikrostrukturnih parametara na žilavost i tvrdoću dobijenih monofaznih i bifaznih biokeramičkih materijala. Nanoindentacijom je utvrđen uticaj veličine zrna i faznog sastava na nanomehaničke karakteristike gustih mikro i nanostrukturnih materijala na bazi HAP i HAP/β-TCP. Svojstva materijala dobijenih mikrotalasnim sinterovanjem, spark plazma sinterovanjem i toplim presovanjem upoređeni su sa svojstvima materijala dobijenih konvencionalnim sinterovanjem.
PB  - Univerzitet u Beogradu, Tehnološko-metalurški fakultet
T1  - Investigation of the influence of processing parameters on the properties of bioceramic materials based on calcium hydroxyapatite and calcium phosphate obtained by different sintering technique
T1  - Ispitivanje uticaja parametara procesiranja na svojstva biokeramičkih materijala na bazi kalcijum-hidroksiapatita i kalcijum-fosfata dobijenih različitim tehnikama sinterovanja
UR  - https://hdl.handle.net/21.15107/rcub_technorep_4599
ER  - 

@phdthesis{
author = "Veljović, Đorđe",
year = "2010",
abstract = "Calcium phosphate bioceramics materials based on hydroxyapatite (HAP) and tricalcium phosphate (TCP), due to their chemical composition, excellent biocompatibility, bioactivity and osteoconduction have received considerable attention as suitable bioceramics for the manufacture of osseous implants. Dense nanostructured and controlled porous forms of hydroxyapatite and calcium phosphate are often used as reparation material in maxillofacial, dental and orthopedic surgery. Careful control of phase composition, grain size and shape and size of pores of sintered bioceramic materials in accordance with good mechanical properties can be key issue for a successful implant. A large number of studies were focused on determining the optimal conditions required to obtain dense or controlled porous HAP and HAP/TCP form suitable for incorporation in living bone. The aim of this PhD thesis was to investigate the processing of dense nanostructured pure hydroxyapatite and biphasic HAP/TCP bioceramics by microwave sintering, spark plasma sintering and hot pressing, starting from stoichiometric and calcium deficient nanosized HAP powders, obtained by two modified chemical precipitation syntheses. The effects of the processing conditions on the microstructure, phase composition and mechanical properties of the obtained materials based on HAP and TCP were investigated. The influence of microstructure and phase composition on the fracture toughness and hardness of sintered HAP and HAP/TCP bioceramics was also defined. The influence of the grain size and phase composition on the nanomechanical behaviour of dense nano and microstructured HAP and biphasic HAP/β-TCP bioceramic materials by nanoindentation was also investigated. The results obtained by microwave sintering, spark plasma sintering and hot pressing were compared with those obtained by conventional sintering methods..., Kalcijum-fosfatni biokeramički materiali na bazi kalcijum-hidroksiapatita (HAP) i trikalcijum-fosfata (TCP), zahvaljujući hemijskom sastavu, biokompatibilnosti, bioaktivnosti i osteokonduktivnosti imaju značajnu ulogu pri izradi koštanih implanta. Guste nanostrukturne i kontrolisano porozne forme biokeramičkih materijala na bazi hidroksiapatita i kalcijum-fosfata imaju veliku primenu u maksiofacialnoj, dentalnoj i ortopedskoj praksi. Pažljiva kontrola faznog sastava, veličine zrna, oblika i dimenzija pora, kao i mehaničkih svojstava sinterovanih biokeramičkih materijala jesu ključni faktori za dobijanje implanata optimalnih svojstava. Danas je ogroman broj istraživanja baziran upravo na definisanju optimalnih uslova procesiranja sa ciljem da se dobiju gusti i kontrolisano porozni biokeramički monofazni kalcijum-hidroksiapatitni i bifazni materijali na bazi HAP i TCP, pogodni za ugradnju u ljudski organizam. Cilj ove doktorske disertacije bio je proučavanje procesa formiranja gustih nanostrukturnih biokeramičkih materijala na bazi kalcijum-hidroksiapatita i kalcijum-fosfata mikrotalasnim sinterovanjem, spark plazma sinterovanjem i toplim presovanjem, polazeći od stehiometrijskih i kalcijum deficitarnih nanočestičnih prahova kalcijum-hidroksiapatita dobijenih modifikovanim precipitacionim sintezama. Ispitan je uticaj svojstava polaznih prahova HAP i parametara procesiranja na mikrostukturne i fazne karakteristike, kao i na mehanička svojstva dobijenih gustih sinterovanih biokeramičkih materijala. Definisan je uticaj mikrostrukturnih parametara na žilavost i tvrdoću dobijenih monofaznih i bifaznih biokeramičkih materijala. Nanoindentacijom je utvrđen uticaj veličine zrna i faznog sastava na nanomehaničke karakteristike gustih mikro i nanostrukturnih materijala na bazi HAP i HAP/β-TCP. Svojstva materijala dobijenih mikrotalasnim sinterovanjem, spark plazma sinterovanjem i toplim presovanjem upoređeni su sa svojstvima materijala dobijenih konvencionalnim sinterovanjem.",
publisher = "Univerzitet u Beogradu, Tehnološko-metalurški fakultet",
title = "Investigation of the influence of processing parameters on the properties of bioceramic materials based on calcium hydroxyapatite and calcium phosphate obtained by different sintering technique, Ispitivanje uticaja parametara procesiranja na svojstva biokeramičkih materijala na bazi kalcijum-hidroksiapatita i kalcijum-fosfata dobijenih različitim tehnikama sinterovanja",
url = "https://hdl.handle.net/21.15107/rcub_technorep_4599"
}

Veljović, Đ.. (2010). Investigation of the influence of processing parameters on the properties of bioceramic materials based on calcium hydroxyapatite and calcium phosphate obtained by different sintering technique. 
Univerzitet u Beogradu, Tehnološko-metalurški fakultet..
https://hdl.handle.net/21.15107/rcub_technorep_4599

Veljović Đ. Investigation of the influence of processing parameters on the properties of bioceramic materials based on calcium hydroxyapatite and calcium phosphate obtained by different sintering technique. 2010;.
https://hdl.handle.net/21.15107/rcub_technorep_4599 .

Veljović, Đorđe, "Investigation of the influence of processing parameters on the properties of bioceramic materials based on calcium hydroxyapatite and calcium phosphate obtained by different sintering technique" (2010),
https://hdl.handle.net/21.15107/rcub_technorep_4599 .

TY  - JOUR
AU  - Jokić, Bojan
AU  - Drmanić, Saša
AU  - Radetić, Tamara
AU  - Krstić, Jugoslav
AU  - Petrović, Rada
AU  - Orlović, Aleksandar
AU  - Janaćković, Đorđe
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1661
AB  - Submicron carbon spherical particles were obtained by polycondensation of resorcinol and formaldehyde in a solution and subsequent ultrasonic spray pyrolysis of the prepared sol. Microscopic characterization indicates the regular spherical shape of the obtained particles and sphere diameters in 200-700 nm range. The carbon spheres are amorphous as confirmed by electron diffraction, EELS, XRD and HREM characterization. Activation procedure was performed with H2O in a nitrogen flow for 15 and 30 min at 800 degrees C. The activation procedure preserved the initial spherical shapes of the particles while the particle porosity and specific surface area were increased. The amount of surface oxygen functionalities was also increased by activation procedure as indicated by FTIR analysis.
PB  - Elsevier, Amsterdam
T2  - Materials Letters
T1  - Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method
EP  - 2176
IS  - 20
SP  - 2173
VL  - 64
DO  - 10.1016/j.matlet.2010.06.066
ER  - 

@article{
author = "Jokić, Bojan and Drmanić, Saša and Radetić, Tamara and Krstić, Jugoslav and Petrović, Rada and Orlović, Aleksandar and Janaćković, Đorđe",
year = "2010",
abstract = "Submicron carbon spherical particles were obtained by polycondensation of resorcinol and formaldehyde in a solution and subsequent ultrasonic spray pyrolysis of the prepared sol. Microscopic characterization indicates the regular spherical shape of the obtained particles and sphere diameters in 200-700 nm range. The carbon spheres are amorphous as confirmed by electron diffraction, EELS, XRD and HREM characterization. Activation procedure was performed with H2O in a nitrogen flow for 15 and 30 min at 800 degrees C. The activation procedure preserved the initial spherical shapes of the particles while the particle porosity and specific surface area were increased. The amount of surface oxygen functionalities was also increased by activation procedure as indicated by FTIR analysis.",
publisher = "Elsevier, Amsterdam",
journal = "Materials Letters",
title = "Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method",
pages = "2176-2173",
number = "20",
volume = "64",
doi = "10.1016/j.matlet.2010.06.066"
}

Jokić, B., Drmanić, S., Radetić, T., Krstić, J., Petrović, R., Orlović, A.,& Janaćković, Đ.. (2010). Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method. in Materials Letters
Elsevier, Amsterdam., 64(20), 2173-2176.
https://doi.org/10.1016/j.matlet.2010.06.066

Jokić B, Drmanić S, Radetić T, Krstić J, Petrović R, Orlović A, Janaćković Đ. Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method. in Materials Letters. 2010;64(20):2173-2176.
doi:10.1016/j.matlet.2010.06.066 .

Jokić, Bojan, Drmanić, Saša, Radetić, Tamara, Krstić, Jugoslav, Petrović, Rada, Orlović, Aleksandar, Janaćković, Đorđe, "Synthesis of submicron carbon spheres by the ultrasonic spray pyrolysis method" in Materials Letters, 64, no. 20 (2010):2173-2176,
https://doi.org/10.1016/j.matlet.2010.06.066 . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Zalite, Ilmars
AU  - Palcevskis, Eriks
AU  - Smičiklas, Ivana D.
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1683
AB  - The effect of microwave sintering conditions on the microstructure, phase composition and mechanical properties of materials based on hydroxyapatite (HAP) and tricalcium phosphate (TCP) was investigated. Fine grained monophase HAP and biphasic HAP/TCP biomaterials were processed starting from stoichiometric and calcium deficient nanosized HAP powders. The HAP samples microwave (MAT) sintered for 15 min at 900 degrees C, with average grain size of 130 nm, showed better densification, higher density and certainly higher hardness and fracture toughness than samples conventionally sintered for 2 h at the same temperature. By comparing MW sintered HAP and HAP/TCP samples, it was concluded that pure HAP ceramics have superior mechanical properties. For monophase MW sintered HAP samples, the decrease in the grain size from 1.59 mu m to 130 nm led to an increase in the fracture toughness from 0.85 MPa m(1/2) to 1.3 MPa m(1/2).
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Microwave sintering of fine grained HAP and HAP/TCP bioceramics
EP  - 603
IS  - 2
SP  - 595
VL  - 36
DO  - 10.1016/j.ceramint.2009.09.038
ER  - 

@article{
author = "Veljović, Đorđe and Zalite, Ilmars and Palcevskis, Eriks and Smičiklas, Ivana D. and Petrović, Rada and Janaćković, Đorđe",
year = "2010",
abstract = "The effect of microwave sintering conditions on the microstructure, phase composition and mechanical properties of materials based on hydroxyapatite (HAP) and tricalcium phosphate (TCP) was investigated. Fine grained monophase HAP and biphasic HAP/TCP biomaterials were processed starting from stoichiometric and calcium deficient nanosized HAP powders. The HAP samples microwave (MAT) sintered for 15 min at 900 degrees C, with average grain size of 130 nm, showed better densification, higher density and certainly higher hardness and fracture toughness than samples conventionally sintered for 2 h at the same temperature. By comparing MW sintered HAP and HAP/TCP samples, it was concluded that pure HAP ceramics have superior mechanical properties. For monophase MW sintered HAP samples, the decrease in the grain size from 1.59 mu m to 130 nm led to an increase in the fracture toughness from 0.85 MPa m(1/2) to 1.3 MPa m(1/2).",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Microwave sintering of fine grained HAP and HAP/TCP bioceramics",
pages = "603-595",
number = "2",
volume = "36",
doi = "10.1016/j.ceramint.2009.09.038"
}

Veljović, Đ., Zalite, I., Palcevskis, E., Smičiklas, I. D., Petrović, R.,& Janaćković, Đ.. (2010). Microwave sintering of fine grained HAP and HAP/TCP bioceramics. in Ceramics International
Elsevier Sci Ltd, Oxford., 36(2), 595-603.
https://doi.org/10.1016/j.ceramint.2009.09.038

Veljović Đ, Zalite I, Palcevskis E, Smičiklas ID, Petrović R, Janaćković Đ. Microwave sintering of fine grained HAP and HAP/TCP bioceramics. in Ceramics International. 2010;36(2):595-603.
doi:10.1016/j.ceramint.2009.09.038 .

Veljović, Đorđe, Zalite, Ilmars, Palcevskis, Eriks, Smičiklas, Ivana D., Petrović, Rada, Janaćković, Đorđe, "Microwave sintering of fine grained HAP and HAP/TCP bioceramics" in Ceramics International, 36, no. 2 (2010):595-603,
https://doi.org/10.1016/j.ceramint.2009.09.038 . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Jokić, Bojan
AU  - Petrović, Rada
AU  - Palcevskis, Eriks
AU  - Dindune, Antonija
AU  - Mihailescu, Ion N.
AU  - Janaćković, Đorđe
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1504
AB  - A nanosized HAP powder was sintered and hot pressed, in order to obtain dense HAP ceramics. In a first series of experiments, the powder was isostatically pressed into uniform green compacts and sintered at temperatures ranging from 1000 degrees C to 1200 degrees C in air atmosphere for different times. In a second series, the isostatically pressed green compacts were hot pressed in argon atmosphere at 900 degrees C, 950 degrees C and 1000 degrees C. The SEM micrograph of the sample sintered at 1200 degrees C for 2 h showed a uniform 3 mu m mean grain size dense microstructure. In the case of hot pressed HAP compacts, full dense, translucent nanostructures were obtained having mean grain size below 100 nm and improved mechanical properties. With the grain size decreasing from 3 mu m to 50 nm, the fracture toughness of pure HAP ceramics increased from 0.28 MPa m(1/2) to 1.52 MPa m(1/2).
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Processing of dense nanostructured HAP ceramics by sintering and hot pressing
EP  - 1413
IS  - 4
SP  - 1407
VL  - 35
DO  - 10.1016/j.ceramint.2008.07.007
ER  - 

@article{
author = "Veljović, Đorđe and Jokić, Bojan and Petrović, Rada and Palcevskis, Eriks and Dindune, Antonija and Mihailescu, Ion N. and Janaćković, Đorđe",
year = "2009",
abstract = "A nanosized HAP powder was sintered and hot pressed, in order to obtain dense HAP ceramics. In a first series of experiments, the powder was isostatically pressed into uniform green compacts and sintered at temperatures ranging from 1000 degrees C to 1200 degrees C in air atmosphere for different times. In a second series, the isostatically pressed green compacts were hot pressed in argon atmosphere at 900 degrees C, 950 degrees C and 1000 degrees C. The SEM micrograph of the sample sintered at 1200 degrees C for 2 h showed a uniform 3 mu m mean grain size dense microstructure. In the case of hot pressed HAP compacts, full dense, translucent nanostructures were obtained having mean grain size below 100 nm and improved mechanical properties. With the grain size decreasing from 3 mu m to 50 nm, the fracture toughness of pure HAP ceramics increased from 0.28 MPa m(1/2) to 1.52 MPa m(1/2).",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Processing of dense nanostructured HAP ceramics by sintering and hot pressing",
pages = "1413-1407",
number = "4",
volume = "35",
doi = "10.1016/j.ceramint.2008.07.007"
}

Veljović, Đ., Jokić, B., Petrović, R., Palcevskis, E., Dindune, A., Mihailescu, I. N.,& Janaćković, Đ.. (2009). Processing of dense nanostructured HAP ceramics by sintering and hot pressing. in Ceramics International
Elsevier Sci Ltd, Oxford., 35(4), 1407-1413.
https://doi.org/10.1016/j.ceramint.2008.07.007

Veljović Đ, Jokić B, Petrović R, Palcevskis E, Dindune A, Mihailescu IN, Janaćković Đ. Processing of dense nanostructured HAP ceramics by sintering and hot pressing. in Ceramics International. 2009;35(4):1407-1413.
doi:10.1016/j.ceramint.2008.07.007 .

Veljović, Đorđe, Jokić, Bojan, Petrović, Rada, Palcevskis, Eriks, Dindune, Antonija, Mihailescu, Ion N., Janaćković, Đorđe, "Processing of dense nanostructured HAP ceramics by sintering and hot pressing" in Ceramics International, 35, no. 4 (2009):1407-1413,
https://doi.org/10.1016/j.ceramint.2008.07.007 . .

TY  - JOUR
AU  - Tanasković, N.
AU  - Radovanović, Željko
AU  - Đokić, Veljko
AU  - Krstić, Jugoslav
AU  - Drmanić, Saša
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1510
AB  - Mesoporous titania with well-crystallized anatase phase was synthesized by nonhydrolytic sol-gel process combined with solvothermal treatment. Titanium-isopropoxide, titanium-tetrachloride, and carbon-tetrachloride were used for synthesis under nitrogen atmosphere in a glove box. The obtained mixture was heated in an autoclave at 140 degrees C for 3 h and 30 h. XRD analysis showed that dry gels contained anatase phase with low crystallinity, while powders obtained by calcination of dry gels at 500 degrees C for 3 h consisted of pure anatase with high crystallinity. SEM analysis of dried gels and powders shows agglomerates of spherical particles of the size similar to 300 nm. The TEM micrographs confirmed the nanoscale size of the titania powders, with the primary particle size of about 20 nm. Titania powders exhibit maximum pore diameter of 13.2 nm and 9.5 nm for gelation time 3 h and 30 h, respectively. The photocatalytic activity of such synthesized titania is superior to that of commercial photocatalyst Degussa P-25.
PB  - Academic Press Ltd- Elsevier Science Ltd, London
T2  - Superlattices and Microstructures
T1  - Synthesis of mesoporous nanocrystalline titania powders by nonhydrolitic sol-gel method
EP  - 222
IS  - 1-2
SP  - 217
VL  - 46
DO  - 10.1016/j.spmi.2008.12.028
ER  - 

@article{
author = "Tanasković, N. and Radovanović, Željko and Đokić, Veljko and Krstić, Jugoslav and Drmanić, Saša and Janaćković, Đorđe and Petrović, Rada",
year = "2009",
abstract = "Mesoporous titania with well-crystallized anatase phase was synthesized by nonhydrolytic sol-gel process combined with solvothermal treatment. Titanium-isopropoxide, titanium-tetrachloride, and carbon-tetrachloride were used for synthesis under nitrogen atmosphere in a glove box. The obtained mixture was heated in an autoclave at 140 degrees C for 3 h and 30 h. XRD analysis showed that dry gels contained anatase phase with low crystallinity, while powders obtained by calcination of dry gels at 500 degrees C for 3 h consisted of pure anatase with high crystallinity. SEM analysis of dried gels and powders shows agglomerates of spherical particles of the size similar to 300 nm. The TEM micrographs confirmed the nanoscale size of the titania powders, with the primary particle size of about 20 nm. Titania powders exhibit maximum pore diameter of 13.2 nm and 9.5 nm for gelation time 3 h and 30 h, respectively. The photocatalytic activity of such synthesized titania is superior to that of commercial photocatalyst Degussa P-25.",
publisher = "Academic Press Ltd- Elsevier Science Ltd, London",
journal = "Superlattices and Microstructures",
title = "Synthesis of mesoporous nanocrystalline titania powders by nonhydrolitic sol-gel method",
pages = "222-217",
number = "1-2",
volume = "46",
doi = "10.1016/j.spmi.2008.12.028"
}

Tanasković, N., Radovanović, Ž., Đokić, V., Krstić, J., Drmanić, S., Janaćković, Đ.,& Petrović, R.. (2009). Synthesis of mesoporous nanocrystalline titania powders by nonhydrolitic sol-gel method. in Superlattices and Microstructures
Academic Press Ltd- Elsevier Science Ltd, London., 46(1-2), 217-222.
https://doi.org/10.1016/j.spmi.2008.12.028

Tanasković N, Radovanović Ž, Đokić V, Krstić J, Drmanić S, Janaćković Đ, Petrović R. Synthesis of mesoporous nanocrystalline titania powders by nonhydrolitic sol-gel method. in Superlattices and Microstructures. 2009;46(1-2):217-222.
doi:10.1016/j.spmi.2008.12.028 .

Tanasković, N., Radovanović, Željko, Đokić, Veljko, Krstić, Jugoslav, Drmanić, Saša, Janaćković, Đorđe, Petrović, Rada, "Synthesis of mesoporous nanocrystalline titania powders by nonhydrolitic sol-gel method" in Superlattices and Microstructures, 46, no. 1-2 (2009):217-222,
https://doi.org/10.1016/j.spmi.2008.12.028 . .

TY  - JOUR
AU  - Tang, C. Y.
AU  - Uskoković, Petar
AU  - Tsui, C. P.
AU  - Veliović, Đ.
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1522
AB  - The aim of the study was to investigate the influence of microstructure and phase composition on the mechanical behaviour of hydroxyapatite (HAp) and biphasic HAp/beta-tricalcium phosphate (beta-TCP) bioceramic materials using nanoindentation. The formation of beta-TCP phase in the HAp ceramic had the predominant influence on the nanomechanical properties of compact ceramics. For investigated microstructures there appear to be a slight decrease in the elastic modulus with increasing load and a higher decrease in hardness, which are in agreement with upper bounds of the results reported in literature. Maximal value of reduced modulus and hardness is yielded with pure HAp, and is measured to be 133.76 GPa for average grain size of 3 mu m and 12.18 GPa for average grain size of 140 urn, respectively. The average modulus and hardness results for HAP/beta-TCP ceramics with higher (101.61 GPa, 6.76 GPa) and lower grain size (115.72 GPa, 8.76 GPa) show sufficient mechanical properties in order to serve as hard tissue replacement material.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Influence of microstructure and phase composition on the nanoindentation characterization of bioceramic materials based on hydroxyapatite
EP  - 2178
IS  - 6
SP  - 2171
VL  - 35
DO  - 10.1016/j.ceramint.2008.11.028
ER  - 

@article{
author = "Tang, C. Y. and Uskoković, Petar and Tsui, C. P. and Veliović, Đ. and Petrović, Rada and Janaćković, Đorđe",
year = "2009",
abstract = "The aim of the study was to investigate the influence of microstructure and phase composition on the mechanical behaviour of hydroxyapatite (HAp) and biphasic HAp/beta-tricalcium phosphate (beta-TCP) bioceramic materials using nanoindentation. The formation of beta-TCP phase in the HAp ceramic had the predominant influence on the nanomechanical properties of compact ceramics. For investigated microstructures there appear to be a slight decrease in the elastic modulus with increasing load and a higher decrease in hardness, which are in agreement with upper bounds of the results reported in literature. Maximal value of reduced modulus and hardness is yielded with pure HAp, and is measured to be 133.76 GPa for average grain size of 3 mu m and 12.18 GPa for average grain size of 140 urn, respectively. The average modulus and hardness results for HAP/beta-TCP ceramics with higher (101.61 GPa, 6.76 GPa) and lower grain size (115.72 GPa, 8.76 GPa) show sufficient mechanical properties in order to serve as hard tissue replacement material.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Influence of microstructure and phase composition on the nanoindentation characterization of bioceramic materials based on hydroxyapatite",
pages = "2178-2171",
number = "6",
volume = "35",
doi = "10.1016/j.ceramint.2008.11.028"
}

Tang, C. Y., Uskoković, P., Tsui, C. P., Veliović, Đ., Petrović, R.,& Janaćković, Đ.. (2009). Influence of microstructure and phase composition on the nanoindentation characterization of bioceramic materials based on hydroxyapatite. in Ceramics International
Elsevier Sci Ltd, Oxford., 35(6), 2171-2178.
https://doi.org/10.1016/j.ceramint.2008.11.028

Tang CY, Uskoković P, Tsui CP, Veliović Đ, Petrović R, Janaćković Đ. Influence of microstructure and phase composition on the nanoindentation characterization of bioceramic materials based on hydroxyapatite. in Ceramics International. 2009;35(6):2171-2178.
doi:10.1016/j.ceramint.2008.11.028 .

Tang, C. Y., Uskoković, Petar, Tsui, C. P., Veliović, Đ., Petrović, Rada, Janaćković, Đorđe, "Influence of microstructure and phase composition on the nanoindentation characterization of bioceramic materials based on hydroxyapatite" in Ceramics International, 35, no. 6 (2009):2171-2178,
https://doi.org/10.1016/j.ceramint.2008.11.028 . .

TY  - JOUR
AU  - Đošić, Marija
AU  - Bibić, Nataša M.
AU  - Mitrić, Miodrag
AU  - Šiljegović, Milorad
AU  - Stojanović, Jovica
AU  - Jokić, Bojan
AU  - Janaćković, Đorđe
AU  - Mišković-Stanković, Vesna
PY  - 2009
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1531
AB  - Surface modification of hydroxyapatite (HA) thin films electrodeposited on titanium was conducted by ion implantation, using nitrogen and argon ions at different constant fluences of 1x10(15), 1x10(16) and 1x10(17) ions/cm(2). SEM and XRD analysis, as well as SRIM calculation, were used to monitor the changes induced by ion bombardment. In the case of HA film implanted with N4+ ions, the unit cell parameters and unit cell volume increase with increasing nitrogen ion fluences. Similarly, the unit cell parameters and unit cell volume increase after Ar6+ ions irradiation to a 1x10(15) ions/cm(2). At higher fluences, the unit cell parameters and unit cell volume decrease when argon ion fluences increase to 1x10(16) and 1x10(17) ions/cm(2). These structural changes are consequence of different mechanism of energy transfer of nitrogen and argon ions to HA film. For nitrogen ion irradiation electron energy loss is predominant, while for argon ion irradiation nuclear energy transfer to HA film prevails.
PB  - Natl Inst Optoelectronics, Bucharest-Magurele
T2  - Journal of Optoelectronics and Advanced Materials
T1  - Electrodeposited hydroxyapatite thin films modified by ion beam irradiation
EP  - 1854
IS  - 11
SP  - 1848
VL  - 11
UR  - https://hdl.handle.net/21.15107/rcub_vinar_3872
ER  - 

@article{
author = "Đošić, Marija and Bibić, Nataša M. and Mitrić, Miodrag and Šiljegović, Milorad and Stojanović, Jovica and Jokić, Bojan and Janaćković, Đorđe and Mišković-Stanković, Vesna",
year = "2009",
abstract = "Surface modification of hydroxyapatite (HA) thin films electrodeposited on titanium was conducted by ion implantation, using nitrogen and argon ions at different constant fluences of 1x10(15), 1x10(16) and 1x10(17) ions/cm(2). SEM and XRD analysis, as well as SRIM calculation, were used to monitor the changes induced by ion bombardment. In the case of HA film implanted with N4+ ions, the unit cell parameters and unit cell volume increase with increasing nitrogen ion fluences. Similarly, the unit cell parameters and unit cell volume increase after Ar6+ ions irradiation to a 1x10(15) ions/cm(2). At higher fluences, the unit cell parameters and unit cell volume decrease when argon ion fluences increase to 1x10(16) and 1x10(17) ions/cm(2). These structural changes are consequence of different mechanism of energy transfer of nitrogen and argon ions to HA film. For nitrogen ion irradiation electron energy loss is predominant, while for argon ion irradiation nuclear energy transfer to HA film prevails.",
publisher = "Natl Inst Optoelectronics, Bucharest-Magurele",
journal = "Journal of Optoelectronics and Advanced Materials",
title = "Electrodeposited hydroxyapatite thin films modified by ion beam irradiation",
pages = "1854-1848",
number = "11",
volume = "11",
url = "https://hdl.handle.net/21.15107/rcub_vinar_3872"
}

Đošić, M., Bibić, N. M., Mitrić, M., Šiljegović, M., Stojanović, J., Jokić, B., Janaćković, Đ.,& Mišković-Stanković, V.. (2009). Electrodeposited hydroxyapatite thin films modified by ion beam irradiation. in Journal of Optoelectronics and Advanced Materials
Natl Inst Optoelectronics, Bucharest-Magurele., 11(11), 1848-1854.
https://hdl.handle.net/21.15107/rcub_vinar_3872

Đošić M, Bibić NM, Mitrić M, Šiljegović M, Stojanović J, Jokić B, Janaćković Đ, Mišković-Stanković V. Electrodeposited hydroxyapatite thin films modified by ion beam irradiation. in Journal of Optoelectronics and Advanced Materials. 2009;11(11):1848-1854.
https://hdl.handle.net/21.15107/rcub_vinar_3872 .

Đošić, Marija, Bibić, Nataša M., Mitrić, Miodrag, Šiljegović, Milorad, Stojanović, Jovica, Jokić, Bojan, Janaćković, Đorđe, Mišković-Stanković, Vesna, "Electrodeposited hydroxyapatite thin films modified by ion beam irradiation" in Journal of Optoelectronics and Advanced Materials, 11, no. 11 (2009):1848-1854,
https://hdl.handle.net/21.15107/rcub_vinar_3872 .

TY  - JOUR
AU  - Lazarević, Slavica
AU  - Janković-Častvan, Ivona
AU  - Tanasković, Dušanka
AU  - Pavićević, Vladimir
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1240
AB  - The sorption of Pb2+, Cd2+, and Sr2+ ions from aqueous solutions by carbonate-substituted calcium hydroxyapatite (HAP) obtained by the hydrothermal decomposition of urea and calcium-ethylenediaminetetraacetic acid chelates was investigated. The shift of the point of zero charge (pH(pzc)) of HAP toward lower pH values in solutions of Pb2+ and Cd2+ ions, which was more pronounced for Pb2+ ions than for Cd2+ ions, indicates that specific adsorption of these cations on HAP had occurred. There was no shift of the pH(pzc) in the solution containing Sr2+ ions, suggesting that specific adsorption of this cation on HAP had not occurred. The sorption isotherms suggest that the sequence of the efficiency of sorption by HAP is Pb2+ gt Cd2+ gt Sr2+. Ion exchange is the main mechanism of removal of Sr2+ ions from aqueous solution by apatite, whereas during the sorption of Cd2+ ions, this mechanism occurs simultaneously with the process of specific adsorption. The interaction of the apatite with Pb2+ ions includes the previously mentioned mechanisms and dissolution of the apatite, followed by the precipitation of lead hydroxyapatite.
PB  - Asce-Amer Soc Civil Engineers, Reston
T2  - Journal of Environmental Engineering
T1  - Sorption of Pb2+, Cd2+, and Sr2+ ions on calcium hydroxyapatite powder obtained by the hydrothermal method
EP  - 688
IS  - 8
SP  - 683
VL  - 134
DO  - 10.1061/(ASCE)0733-9372(2008)134:8(683)
ER  - 

@article{
author = "Lazarević, Slavica and Janković-Častvan, Ivona and Tanasković, Dušanka and Pavićević, Vladimir and Janaćković, Đorđe and Petrović, Rada",
year = "2008",
abstract = "The sorption of Pb2+, Cd2+, and Sr2+ ions from aqueous solutions by carbonate-substituted calcium hydroxyapatite (HAP) obtained by the hydrothermal decomposition of urea and calcium-ethylenediaminetetraacetic acid chelates was investigated. The shift of the point of zero charge (pH(pzc)) of HAP toward lower pH values in solutions of Pb2+ and Cd2+ ions, which was more pronounced for Pb2+ ions than for Cd2+ ions, indicates that specific adsorption of these cations on HAP had occurred. There was no shift of the pH(pzc) in the solution containing Sr2+ ions, suggesting that specific adsorption of this cation on HAP had not occurred. The sorption isotherms suggest that the sequence of the efficiency of sorption by HAP is Pb2+ gt Cd2+ gt Sr2+. Ion exchange is the main mechanism of removal of Sr2+ ions from aqueous solution by apatite, whereas during the sorption of Cd2+ ions, this mechanism occurs simultaneously with the process of specific adsorption. The interaction of the apatite with Pb2+ ions includes the previously mentioned mechanisms and dissolution of the apatite, followed by the precipitation of lead hydroxyapatite.",
publisher = "Asce-Amer Soc Civil Engineers, Reston",
journal = "Journal of Environmental Engineering",
title = "Sorption of Pb2+, Cd2+, and Sr2+ ions on calcium hydroxyapatite powder obtained by the hydrothermal method",
pages = "688-683",
number = "8",
volume = "134",
doi = "10.1061/(ASCE)0733-9372(2008)134:8(683)"
}

Lazarević, S., Janković-Častvan, I., Tanasković, D., Pavićević, V., Janaćković, Đ.,& Petrović, R.. (2008). Sorption of Pb2+, Cd2+, and Sr2+ ions on calcium hydroxyapatite powder obtained by the hydrothermal method. in Journal of Environmental Engineering
Asce-Amer Soc Civil Engineers, Reston., 134(8), 683-688.
https://doi.org/10.1061/(ASCE)0733-9372(2008)134:8(683)

Lazarević S, Janković-Častvan I, Tanasković D, Pavićević V, Janaćković Đ, Petrović R. Sorption of Pb2+, Cd2+, and Sr2+ ions on calcium hydroxyapatite powder obtained by the hydrothermal method. in Journal of Environmental Engineering. 2008;134(8):683-688.
doi:10.1061/(ASCE)0733-9372(2008)134:8(683) .

Lazarević, Slavica, Janković-Častvan, Ivona, Tanasković, Dušanka, Pavićević, Vladimir, Janaćković, Đorđe, Petrović, Rada, "Sorption of Pb2+, Cd2+, and Sr2+ ions on calcium hydroxyapatite powder obtained by the hydrothermal method" in Journal of Environmental Engineering, 134, no. 8 (2008):683-688,
https://doi.org/10.1061/(ASCE)0733-9372(2008)134:8(683) . .

TY  - JOUR
AU  - Radonjić, L.
AU  - Todorović, M.
AU  - Miladinović, Jelena
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1259
AB  - Ferroelectric nanostructured barium titanate (BT) thin films derived by a modified sol-gel process were formed by a deep coating method on Si (100) substrate. In this work was investigated the influence of different types and amounts of water (free water directly added in process and crystalline water from barium precursors) and of different barium precursors (hydroxide and acetate) on the gel-structure evolution and the barium titanate thin film crystallization. The IR-spectroscopy and X-ray diffraction analysis were used for sample characterization. Experimental results show that crystalline water from barium hydroxide octahydrate stabilizes the cubic phase of barium titanate. Barium titanate crystallizes in the tetragonal form in thin films when sols were prepared with free water and Ba-acetate or Ba-hydroxide monohydrate as precursors. The type of Ba-precursor used in preparation of sols effects the rate of crystallization of the BT in thin films, making it slower in the case when as precursor was used Ba-acetate than Ba-hydroxides. The prepared BT-thin films demonstrated good adhesion towards substrate and were smooth and uniform.
PB  - Springer, New York
T2  - Journal of Sol-Gel Science and Technology
T1  - Structural evolution of nanostructured barium titanate thin film sol-gel derived
EP  - 132
IS  - 2
SP  - 125
VL  - 45
DO  - 10.1007/s10971-007-1664-1
ER  - 

@article{
author = "Radonjić, L. and Todorović, M. and Miladinović, Jelena",
year = "2008",
abstract = "Ferroelectric nanostructured barium titanate (BT) thin films derived by a modified sol-gel process were formed by a deep coating method on Si (100) substrate. In this work was investigated the influence of different types and amounts of water (free water directly added in process and crystalline water from barium precursors) and of different barium precursors (hydroxide and acetate) on the gel-structure evolution and the barium titanate thin film crystallization. The IR-spectroscopy and X-ray diffraction analysis were used for sample characterization. Experimental results show that crystalline water from barium hydroxide octahydrate stabilizes the cubic phase of barium titanate. Barium titanate crystallizes in the tetragonal form in thin films when sols were prepared with free water and Ba-acetate or Ba-hydroxide monohydrate as precursors. The type of Ba-precursor used in preparation of sols effects the rate of crystallization of the BT in thin films, making it slower in the case when as precursor was used Ba-acetate than Ba-hydroxides. The prepared BT-thin films demonstrated good adhesion towards substrate and were smooth and uniform.",
publisher = "Springer, New York",
journal = "Journal of Sol-Gel Science and Technology",
title = "Structural evolution of nanostructured barium titanate thin film sol-gel derived",
pages = "132-125",
number = "2",
volume = "45",
doi = "10.1007/s10971-007-1664-1"
}

Radonjić, L., Todorović, M.,& Miladinović, J.. (2008). Structural evolution of nanostructured barium titanate thin film sol-gel derived. in Journal of Sol-Gel Science and Technology
Springer, New York., 45(2), 125-132.
https://doi.org/10.1007/s10971-007-1664-1

Radonjić L, Todorović M, Miladinović J. Structural evolution of nanostructured barium titanate thin film sol-gel derived. in Journal of Sol-Gel Science and Technology. 2008;45(2):125-132.
doi:10.1007/s10971-007-1664-1 .

Radonjić, L., Todorović, M., Miladinović, Jelena, "Structural evolution of nanostructured barium titanate thin film sol-gel derived" in Journal of Sol-Gel Science and Technology, 45, no. 2 (2008):125-132,
https://doi.org/10.1007/s10971-007-1664-1 . .

TY  - JOUR
AU  - Tanasković, Dušanka
AU  - Veljović, Đorđe
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
AU  - Mitrić, Miodrag
AU  - Cojanu, C.
AU  - Ristoscu, Carmen
AU  - Mihailescu, Ion N.
PY  - 2008
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1220
AB  - Pulsed laser deposition was used to obtain functionally graded bioactive glass coatings on titanium substrates. An UV KrF* (lambda=248 nm, tau gt 7 ns) excimer laser was used for the multi-pulse irradiation of the targets. The depositions were performed in oxygen while keeping substrate temperature at 400 degrees C. We used sintered glass targets in the system SiO2-Na2O-K2O-CaO-MgO-P2O5 that differed in SiO2 content, which was either 57 wt.% (6P57) or 61 wt.% (6P61). A glass 6P61 was used as the first layer in direct contact with the metallic substrate, while the outer bioactive layer was made of glass 6P57. Both the bioactive coatings and the bulk glasses were analyzed by Fourier transform infrared spectrometry (FTIR), grazing incidence X-ray diffraction (GIXRD), and scanning electron microscopy (SEM). The FTIR spectra of the glass powders and glass coatings showed the main vibration modes of the Si-O-Si groups. GIXRD analysis confirmed that the glass coatings had an amorphous structure. The SEM micrographs of the glass coatings showed the films to consist of droplets with diameters ranging from 0.2 to 5 Pm. SEM was used to determine the rate of apatite formation on the coating when exposed to simulated body fluid (SBF) solution for 7 days. We demonstrated that pulsed laser deposition leads to good glass-metal adhesion on the substrate and well attached bioactive particles on the surface. We consider therefore this method appropriate for forming implants that can develop an apatite layer after immersion in SBF.
PB  - Trans Tech Publications Ltd, Durnten-Zurich
T2  - Key Engineering Materials
T1  - Double-layer bioactive glass coatings obtained by pulsed laser deposition
EP  - 280
SP  - 277
VL  - 361-363 I
UR  - https://hdl.handle.net/21.15107/rcub_vinar_6718
ER  - 

@article{
author = "Tanasković, Dušanka and Veljović, Đorđe and Petrović, Rada and Janaćković, Đorđe and Mitrić, Miodrag and Cojanu, C. and Ristoscu, Carmen and Mihailescu, Ion N.",
year = "2008",
abstract = "Pulsed laser deposition was used to obtain functionally graded bioactive glass coatings on titanium substrates. An UV KrF* (lambda=248 nm, tau gt 7 ns) excimer laser was used for the multi-pulse irradiation of the targets. The depositions were performed in oxygen while keeping substrate temperature at 400 degrees C. We used sintered glass targets in the system SiO2-Na2O-K2O-CaO-MgO-P2O5 that differed in SiO2 content, which was either 57 wt.% (6P57) or 61 wt.% (6P61). A glass 6P61 was used as the first layer in direct contact with the metallic substrate, while the outer bioactive layer was made of glass 6P57. Both the bioactive coatings and the bulk glasses were analyzed by Fourier transform infrared spectrometry (FTIR), grazing incidence X-ray diffraction (GIXRD), and scanning electron microscopy (SEM). The FTIR spectra of the glass powders and glass coatings showed the main vibration modes of the Si-O-Si groups. GIXRD analysis confirmed that the glass coatings had an amorphous structure. The SEM micrographs of the glass coatings showed the films to consist of droplets with diameters ranging from 0.2 to 5 Pm. SEM was used to determine the rate of apatite formation on the coating when exposed to simulated body fluid (SBF) solution for 7 days. We demonstrated that pulsed laser deposition leads to good glass-metal adhesion on the substrate and well attached bioactive particles on the surface. We consider therefore this method appropriate for forming implants that can develop an apatite layer after immersion in SBF.",
publisher = "Trans Tech Publications Ltd, Durnten-Zurich",
journal = "Key Engineering Materials",
title = "Double-layer bioactive glass coatings obtained by pulsed laser deposition",
pages = "280-277",
volume = "361-363 I",
url = "https://hdl.handle.net/21.15107/rcub_vinar_6718"
}

Tanasković, D., Veljović, Đ., Petrović, R., Janaćković, Đ., Mitrić, M., Cojanu, C., Ristoscu, C.,& Mihailescu, I. N.. (2008). Double-layer bioactive glass coatings obtained by pulsed laser deposition. in Key Engineering Materials
Trans Tech Publications Ltd, Durnten-Zurich., 361-363 I, 277-280.
https://hdl.handle.net/21.15107/rcub_vinar_6718

Tanasković D, Veljović Đ, Petrović R, Janaćković Đ, Mitrić M, Cojanu C, Ristoscu C, Mihailescu IN. Double-layer bioactive glass coatings obtained by pulsed laser deposition. in Key Engineering Materials. 2008;361-363 I:277-280.
https://hdl.handle.net/21.15107/rcub_vinar_6718 .

Tanasković, Dušanka, Veljović, Đorđe, Petrović, Rada, Janaćković, Đorđe, Mitrić, Miodrag, Cojanu, C., Ristoscu, Carmen, Mihailescu, Ion N., "Double-layer bioactive glass coatings obtained by pulsed laser deposition" in Key Engineering Materials, 361-363 I (2008):277-280,
https://hdl.handle.net/21.15107/rcub_vinar_6718 .

TY  - JOUR
AU  - Janković-Častvan, Ivona
AU  - Lazarević, Slavica
AU  - Tanasković, Dušanka
AU  - Orlović, Aleksandar
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1172
AB  - Cordierite gel was synthesized by non-hydrolytic sol-gel route, starting from aluminum chloride, TEOS and magnesium chloride dissolved in absolute ethanol. Crystallization of p.-cordierite from gel at temperatures between 900 and 1000 degrees C was confirmed by differential thermal analyses, X-ray and FTIR spectroscopy. Higher calcination temperature resulted in the transformation of mu- to alpha-cordierite. The value of Avrami parameter n = 2.23 for the mu-cordierite crystallization indicates contribution of different simultaneous mechanisms: homogeneous nucleation and three-dimensional crystallite growth due to homogeneity of gel and surface crystallization due to submicron particles of the gel.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route
EP  - 1268
IS  - 7
SP  - 1263
VL  - 33
DO  - 10.1016/j.ceramint.2006.05.003
ER  - 

@article{
author = "Janković-Častvan, Ivona and Lazarević, Slavica and Tanasković, Dušanka and Orlović, Aleksandar and Petrović, Rada and Janaćković, Đorđe",
year = "2007",
abstract = "Cordierite gel was synthesized by non-hydrolytic sol-gel route, starting from aluminum chloride, TEOS and magnesium chloride dissolved in absolute ethanol. Crystallization of p.-cordierite from gel at temperatures between 900 and 1000 degrees C was confirmed by differential thermal analyses, X-ray and FTIR spectroscopy. Higher calcination temperature resulted in the transformation of mu- to alpha-cordierite. The value of Avrami parameter n = 2.23 for the mu-cordierite crystallization indicates contribution of different simultaneous mechanisms: homogeneous nucleation and three-dimensional crystallite growth due to homogeneity of gel and surface crystallization due to submicron particles of the gel.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route",
pages = "1268-1263",
number = "7",
volume = "33",
doi = "10.1016/j.ceramint.2006.05.003"
}

Janković-Častvan, I., Lazarević, S., Tanasković, D., Orlović, A., Petrović, R.,& Janaćković, Đ.. (2007). Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route. in Ceramics International
Elsevier Sci Ltd, Oxford., 33(7), 1263-1268.
https://doi.org/10.1016/j.ceramint.2006.05.003

Janković-Častvan I, Lazarević S, Tanasković D, Orlović A, Petrović R, Janaćković Đ. Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route. in Ceramics International. 2007;33(7):1263-1268.
doi:10.1016/j.ceramint.2006.05.003 .

Janković-Častvan, Ivona, Lazarević, Slavica, Tanasković, Dušanka, Orlović, Aleksandar, Petrović, Rada, Janaćković, Đorđe, "Phase transformation in cordierite gel synthesized by non-hydrolytic sol-gel route" in Ceramics International, 33, no. 7 (2007):1263-1268,
https://doi.org/10.1016/j.ceramint.2006.05.003 . .

TY  - JOUR
AU  - Jokić, Bojan
AU  - Tanasković, Dušanka
AU  - Janković-Častvan, Ivona
AU  - Drmanić, Saša
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1090
AB  - Nanosized calcium hydroxyapatite particles were synthesized by the catalytic decomposition of urea with urease. The influence of the synthesis parameters, i.e., temperature and ratio of the reagents/urease concentrations, on the size and morphology of the hydroxyapatite particles were investigated. As reagents for the synthesis of hydroxyapatite, various amounts of CaCl2, NaH2PO4, urea, and urease were used. The urease-catalyzed decomposition of urea leads to the homogeneous precipitation of hydroxyapatite because of the release of OH- ions during the hydrolysis of urea. In the same process, CO32- ions are also released and incorporated into the crystal structure of the hydroxyapatite. In the temperature range from 30-40 degrees C, it was found that low crystalline carbonate hydroxyapatite was formed in all cases. It was found that decreasing the ratio of the concentrations of the reagents to the urease concentration leads to decrease in the particle size to below 100 nm and the morphology changes from leafy-like to spherical.
PB  - Cambridge Univ Press, New York
T2  - Journal of Materials Research
T1  - Synthesis of nanosized calcium hydroxyapatite particles by the catalytic decomposition of urea with urease
EP  - 1161
IS  - 5
SP  - 1156
VL  - 22
DO  - 10.1557/JMR.2007.0170
ER  - 

@article{
author = "Jokić, Bojan and Tanasković, Dušanka and Janković-Častvan, Ivona and Drmanić, Saša and Petrović, Rada and Janaćković, Đorđe",
year = "2007",
abstract = "Nanosized calcium hydroxyapatite particles were synthesized by the catalytic decomposition of urea with urease. The influence of the synthesis parameters, i.e., temperature and ratio of the reagents/urease concentrations, on the size and morphology of the hydroxyapatite particles were investigated. As reagents for the synthesis of hydroxyapatite, various amounts of CaCl2, NaH2PO4, urea, and urease were used. The urease-catalyzed decomposition of urea leads to the homogeneous precipitation of hydroxyapatite because of the release of OH- ions during the hydrolysis of urea. In the same process, CO32- ions are also released and incorporated into the crystal structure of the hydroxyapatite. In the temperature range from 30-40 degrees C, it was found that low crystalline carbonate hydroxyapatite was formed in all cases. It was found that decreasing the ratio of the concentrations of the reagents to the urease concentration leads to decrease in the particle size to below 100 nm and the morphology changes from leafy-like to spherical.",
publisher = "Cambridge Univ Press, New York",
journal = "Journal of Materials Research",
title = "Synthesis of nanosized calcium hydroxyapatite particles by the catalytic decomposition of urea with urease",
pages = "1161-1156",
number = "5",
volume = "22",
doi = "10.1557/JMR.2007.0170"
}

Jokić, B., Tanasković, D., Janković-Častvan, I., Drmanić, S., Petrović, R.,& Janaćković, Đ.. (2007). Synthesis of nanosized calcium hydroxyapatite particles by the catalytic decomposition of urea with urease. in Journal of Materials Research
Cambridge Univ Press, New York., 22(5), 1156-1161.
https://doi.org/10.1557/JMR.2007.0170

Jokić B, Tanasković D, Janković-Častvan I, Drmanić S, Petrović R, Janaćković Đ. Synthesis of nanosized calcium hydroxyapatite particles by the catalytic decomposition of urea with urease. in Journal of Materials Research. 2007;22(5):1156-1161.
doi:10.1557/JMR.2007.0170 .

Jokić, Bojan, Tanasković, Dušanka, Janković-Častvan, Ivona, Drmanić, Saša, Petrović, Rada, Janaćković, Đorđe, "Synthesis of nanosized calcium hydroxyapatite particles by the catalytic decomposition of urea with urease" in Journal of Materials Research, 22, no. 5 (2007):1156-1161,
https://doi.org/10.1557/JMR.2007.0170 . .

TY  - JOUR
AU  - Tanasković, Dušanka
AU  - Jokić, Bojan
AU  - Socol, Gabriel
AU  - Popescu, A. C.
AU  - Mihailescu, Ion N.
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1149
AB  - Functionally graded glass-apatite multistructures were synthesized by pulsed laser deposition on Ti substrates. We used sintered targets of hydroxyapatite Ca-10(PO4)(6)(OH)(2), or bioglasses in the system SiO2-Na2O-K2O-CaO-MgO-P2O5 with SiO2 content of either 57 wt.% (6P57) or 61 wt.% (061). A UV KrF* (lambda = 248 nm, tau  gt  7 ns) excimer laser source was used for the multipulse laser ablation of the targets. The hydroxyapatite thin films were obtained in H2O Vapors, while the bioglass layers were deposited in O-2. Thin films of 6P61 were deposited in direct contact with Ti, because Ti and this glass have similar thermal expansion behaviors, which ensure good bioglass adhesion to the substrate. This glass, however, is not bioactive, so yet more depositions of 6P57 bioglass and/or hydroxyapatite thin films were performed. All structures with hydroxyapatite overcoating were post-treated in a flux of water vapors. The obtained multistructures were characterized by various techniques. Xray investigations of the coatings found small amounts of crystalline hydroxyapatite in the outer layers. The scanning electron microscopy analyses revealed homogeneous coatings with good adhesion to the Ti substrate. Our studies showed that the multistructures we had obtained were compatible with further use in biomimetic metallic implants with glass-apatite coating applications.
PB  - Elsevier Science Bv, Amsterdam
T2  - Applied Surface Science
T1  - Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition
EP  - 1282
IS  - 4
SP  - 1279
VL  - 254
DO  - 10.1016/j.apsusc.2007.08.009
ER  - 

@article{
author = "Tanasković, Dušanka and Jokić, Bojan and Socol, Gabriel and Popescu, A. C. and Mihailescu, Ion N. and Petrović, Rada and Janaćković, Đorđe",
year = "2007",
abstract = "Functionally graded glass-apatite multistructures were synthesized by pulsed laser deposition on Ti substrates. We used sintered targets of hydroxyapatite Ca-10(PO4)(6)(OH)(2), or bioglasses in the system SiO2-Na2O-K2O-CaO-MgO-P2O5 with SiO2 content of either 57 wt.% (6P57) or 61 wt.% (061). A UV KrF* (lambda = 248 nm, tau  gt  7 ns) excimer laser source was used for the multipulse laser ablation of the targets. The hydroxyapatite thin films were obtained in H2O Vapors, while the bioglass layers were deposited in O-2. Thin films of 6P61 were deposited in direct contact with Ti, because Ti and this glass have similar thermal expansion behaviors, which ensure good bioglass adhesion to the substrate. This glass, however, is not bioactive, so yet more depositions of 6P57 bioglass and/or hydroxyapatite thin films were performed. All structures with hydroxyapatite overcoating were post-treated in a flux of water vapors. The obtained multistructures were characterized by various techniques. Xray investigations of the coatings found small amounts of crystalline hydroxyapatite in the outer layers. The scanning electron microscopy analyses revealed homogeneous coatings with good adhesion to the Ti substrate. Our studies showed that the multistructures we had obtained were compatible with further use in biomimetic metallic implants with glass-apatite coating applications.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Applied Surface Science",
title = "Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition",
pages = "1282-1279",
number = "4",
volume = "254",
doi = "10.1016/j.apsusc.2007.08.009"
}

Tanasković, D., Jokić, B., Socol, G., Popescu, A. C., Mihailescu, I. N., Petrović, R.,& Janaćković, Đ.. (2007). Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition. in Applied Surface Science
Elsevier Science Bv, Amsterdam., 254(4), 1279-1282.
https://doi.org/10.1016/j.apsusc.2007.08.009

Tanasković D, Jokić B, Socol G, Popescu AC, Mihailescu IN, Petrović R, Janaćković Đ. Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition. in Applied Surface Science. 2007;254(4):1279-1282.
doi:10.1016/j.apsusc.2007.08.009 .

Tanasković, Dušanka, Jokić, Bojan, Socol, Gabriel, Popescu, A. C., Mihailescu, Ion N., Petrović, Rada, Janaćković, Đorđe, "Synthesis of functionally graded bioactive glass-apatite multistructures on Ti substrates by pulsed laser deposition" in Applied Surface Science, 254, no. 4 (2007):1279-1282,
https://doi.org/10.1016/j.apsusc.2007.08.009 . .

TY  - JOUR
AU  - Stojanović, D.
AU  - Jokić, Bojan
AU  - Veljović, Đorđe
AU  - Petrović, R.
AU  - Uskoković, Petar
AU  - Janaćković, Đorđe
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1120
AB  - Titanium and titanium alloys are widely used as materials for implants, because of their mechanical properties and nontoxic behaviour, but unfortunately, are bioinert. In order to solve this problem, the metal implant could be coated with bioactive materials with good adhesion to metal and could be also bonded interfacially to the bone. The aim of this work is to investigate the synthesis of functionally graded glass-apatite coating on Ti6A14V alloys by the electrophoretic method. In order to enhance bioactivity of the surface, nanostructured hydroxyapatite particles were embedded in the glass coating. The influence of synthesis condition such as deposition voltage and time on the coating properties and deposit weights were examined. It was shown that controlling the deposition voltage and time, the deposition weight and thickness of coating could be controlled. It was shown that electrophoretic deposition can be successfully employed for the preparation graded glass-apatite coating on Ti6A14V substrate.
PB  - Elsevier Sci Ltd, Oxford
T2  - Journal of the European Ceramic Society
T1  - Bioactive glass-apatite composite coating for titanium implant synthesized by electrophoretic deposition
EP  - 1599
IS  - 2-3
SP  - 1595
VL  - 27
DO  - 10.1016/j.jeurceramsoc.2006.04.111
ER  - 

@article{
author = "Stojanović, D. and Jokić, Bojan and Veljović, Đorđe and Petrović, R. and Uskoković, Petar and Janaćković, Đorđe",
year = "2007",
abstract = "Titanium and titanium alloys are widely used as materials for implants, because of their mechanical properties and nontoxic behaviour, but unfortunately, are bioinert. In order to solve this problem, the metal implant could be coated with bioactive materials with good adhesion to metal and could be also bonded interfacially to the bone. The aim of this work is to investigate the synthesis of functionally graded glass-apatite coating on Ti6A14V alloys by the electrophoretic method. In order to enhance bioactivity of the surface, nanostructured hydroxyapatite particles were embedded in the glass coating. The influence of synthesis condition such as deposition voltage and time on the coating properties and deposit weights were examined. It was shown that controlling the deposition voltage and time, the deposition weight and thickness of coating could be controlled. It was shown that electrophoretic deposition can be successfully employed for the preparation graded glass-apatite coating on Ti6A14V substrate.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Journal of the European Ceramic Society",
title = "Bioactive glass-apatite composite coating for titanium implant synthesized by electrophoretic deposition",
pages = "1599-1595",
number = "2-3",
volume = "27",
doi = "10.1016/j.jeurceramsoc.2006.04.111"
}

Stojanović, D., Jokić, B., Veljović, Đ., Petrović, R., Uskoković, P.,& Janaćković, Đ.. (2007). Bioactive glass-apatite composite coating for titanium implant synthesized by electrophoretic deposition. in Journal of the European Ceramic Society
Elsevier Sci Ltd, Oxford., 27(2-3), 1595-1599.
https://doi.org/10.1016/j.jeurceramsoc.2006.04.111

Stojanović D, Jokić B, Veljović Đ, Petrović R, Uskoković P, Janaćković Đ. Bioactive glass-apatite composite coating for titanium implant synthesized by electrophoretic deposition. in Journal of the European Ceramic Society. 2007;27(2-3):1595-1599.
doi:10.1016/j.jeurceramsoc.2006.04.111 .

Stojanović, D., Jokić, Bojan, Veljović, Đorđe, Petrović, R., Uskoković, Petar, Janaćković, Đorđe, "Bioactive glass-apatite composite coating for titanium implant synthesized by electrophoretic deposition" in Journal of the European Ceramic Society, 27, no. 2-3 (2007):1595-1599,
https://doi.org/10.1016/j.jeurceramsoc.2006.04.111 . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Jokić, Bojan
AU  - Janković-Častvan, Ivona
AU  - Smičiklas, Ivana D.
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1021
AB  - The influences of temperature and time on sintering behaviour of nanosized HAP powder were investigate in this paper. The calcium hydroxyapatite powder, with the average crystallite size of 34 +/- 1 nm, was uniaxially pressed at a pressure of 500 MPa. Obtained green compacts were sintered at temperature ranging from 1000 degrees C to 1200 degrees C in air atmosphere at various times. According to the results of scanning electron microscopy, X-ray and FTIR analyses, it is shown that HAP compacts with dense microstructure and average grain size below 250 nm is obtained.
PB  - Trans Tech Publications Ltd, Durnten-Zurich
T2  - Key Engineering Materials
T1  - Sintering behaviour of nanosized HAP powder
EP  - 262
SP  - 259
VL  - 330-332 I
UR  - https://hdl.handle.net/21.15107/rcub_technorep_1021
ER  - 

@article{
author = "Veljović, Đorđe and Jokić, Bojan and Janković-Častvan, Ivona and Smičiklas, Ivana D. and Petrović, Rada and Janaćković, Đorđe",
year = "2007",
abstract = "The influences of temperature and time on sintering behaviour of nanosized HAP powder were investigate in this paper. The calcium hydroxyapatite powder, with the average crystallite size of 34 +/- 1 nm, was uniaxially pressed at a pressure of 500 MPa. Obtained green compacts were sintered at temperature ranging from 1000 degrees C to 1200 degrees C in air atmosphere at various times. According to the results of scanning electron microscopy, X-ray and FTIR analyses, it is shown that HAP compacts with dense microstructure and average grain size below 250 nm is obtained.",
publisher = "Trans Tech Publications Ltd, Durnten-Zurich",
journal = "Key Engineering Materials",
title = "Sintering behaviour of nanosized HAP powder",
pages = "262-259",
volume = "330-332 I",
url = "https://hdl.handle.net/21.15107/rcub_technorep_1021"
}

Veljović, Đ., Jokić, B., Janković-Častvan, I., Smičiklas, I. D., Petrović, R.,& Janaćković, Đ.. (2007). Sintering behaviour of nanosized HAP powder. in Key Engineering Materials
Trans Tech Publications Ltd, Durnten-Zurich., 330-332 I, 259-262.
https://hdl.handle.net/21.15107/rcub_technorep_1021

Veljović Đ, Jokić B, Janković-Častvan I, Smičiklas ID, Petrović R, Janaćković Đ. Sintering behaviour of nanosized HAP powder. in Key Engineering Materials. 2007;330-332 I:259-262.
https://hdl.handle.net/21.15107/rcub_technorep_1021 .

Veljović, Đorđe, Jokić, Bojan, Janković-Častvan, Ivona, Smičiklas, Ivana D., Petrović, Rada, Janaćković, Đorđe, "Sintering behaviour of nanosized HAP powder" in Key Engineering Materials, 330-332 I (2007):259-262,
https://hdl.handle.net/21.15107/rcub_technorep_1021 .

TY  - JOUR
AU  - Lazarević, Slavica
AU  - Janković-Častvan, Ivona
AU  - Jovanović, Dušan
AU  - Milonjić, Slobodan K.
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2007
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1157
AB  - The adsorption mechanisms of Ph2+, Cd2+ and Sr2+ ions on natural sepiolite and the influence of acid treatment on the adsorption capacity of sepiolite were investigated. The point of zero charge pH(pzc), is 7.4 +/- 0.1 for natural sepiolite and 6.9 +/- 0.1 for partially acid-activated sepiolite. The shift of the pH(pzc) of sepiolites toward lower pH values in solutions of Ph2+ and Cd2+ ions indicates that specific adsorption of these cations on natural and acid-activated sepiolites occurred, which was more pronounced for Pb2+ ions than for Cd2+ ions. There was no shift of the pH(pzc) in Solution containing Sr2+ ions, suggesting that specific adsorption of this cation did not occur. The affinity for ion exchange with the Mg2+ ions from the sepiolite structure was the highest for Pb2+ ions, then Cd2+, whereas the affinity for Sr2+ ions was negligible. The adsorption isotherms suggest that the sequence of the efficiency of the sepiolites adsorption is Ph2+ gt Cd2+ gt Sr2+. The retention of Pb2+ and Cd2+ ions by sepiolite occurs dominantly by specific adsorption and exchange of Mg2+ ions from the sepiolite structure. The concentration in the external outer sphere of the Stem layer by electrostatic forces is the dominant mechanism for the retention of Sr2+ ions on the surface of sepiolites. Despite increases in the surface areas upon acid activation, improvements in the adsorption were not observed, as a result of the decreasing number of Mg-OH groups, as main centers for specific adsorption, and the number of Mg2+ ions available for ion exchange with Pb2+, Cd2+ and Sr2+ ions. The removal of Mg-OH groups from the sepiolite also resulted in a decrease in the point of zero charge and an increase of the relative surface acidity, from 2.6 +/- 0.1 for the natural to 6.4 +/- 0.1 for the acid-activated sepiolite.
PB  - Elsevier Science Bv, Amsterdam
T2  - Applied Clay Science
T1  - Adsorption of Pb2+, Cd2+ and Sr2+ ions onto natural and acid-activated sepiolites
EP  - 57
IS  - 1-2
SP  - 47
VL  - 37
DO  - 10.1016/j.clay.2006.11.008
ER  - 

@article{
author = "Lazarević, Slavica and Janković-Častvan, Ivona and Jovanović, Dušan and Milonjić, Slobodan K. and Janaćković, Đorđe and Petrović, Rada",
year = "2007",
abstract = "The adsorption mechanisms of Ph2+, Cd2+ and Sr2+ ions on natural sepiolite and the influence of acid treatment on the adsorption capacity of sepiolite were investigated. The point of zero charge pH(pzc), is 7.4 +/- 0.1 for natural sepiolite and 6.9 +/- 0.1 for partially acid-activated sepiolite. The shift of the pH(pzc) of sepiolites toward lower pH values in solutions of Ph2+ and Cd2+ ions indicates that specific adsorption of these cations on natural and acid-activated sepiolites occurred, which was more pronounced for Pb2+ ions than for Cd2+ ions. There was no shift of the pH(pzc) in Solution containing Sr2+ ions, suggesting that specific adsorption of this cation did not occur. The affinity for ion exchange with the Mg2+ ions from the sepiolite structure was the highest for Pb2+ ions, then Cd2+, whereas the affinity for Sr2+ ions was negligible. The adsorption isotherms suggest that the sequence of the efficiency of the sepiolites adsorption is Ph2+ gt Cd2+ gt Sr2+. The retention of Pb2+ and Cd2+ ions by sepiolite occurs dominantly by specific adsorption and exchange of Mg2+ ions from the sepiolite structure. The concentration in the external outer sphere of the Stem layer by electrostatic forces is the dominant mechanism for the retention of Sr2+ ions on the surface of sepiolites. Despite increases in the surface areas upon acid activation, improvements in the adsorption were not observed, as a result of the decreasing number of Mg-OH groups, as main centers for specific adsorption, and the number of Mg2+ ions available for ion exchange with Pb2+, Cd2+ and Sr2+ ions. The removal of Mg-OH groups from the sepiolite also resulted in a decrease in the point of zero charge and an increase of the relative surface acidity, from 2.6 +/- 0.1 for the natural to 6.4 +/- 0.1 for the acid-activated sepiolite.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Applied Clay Science",
title = "Adsorption of Pb2+, Cd2+ and Sr2+ ions onto natural and acid-activated sepiolites",
pages = "57-47",
number = "1-2",
volume = "37",
doi = "10.1016/j.clay.2006.11.008"
}

Lazarević, S., Janković-Častvan, I., Jovanović, D., Milonjić, S. K., Janaćković, Đ.,& Petrović, R.. (2007). Adsorption of Pb2+, Cd2+ and Sr2+ ions onto natural and acid-activated sepiolites. in Applied Clay Science
Elsevier Science Bv, Amsterdam., 37(1-2), 47-57.
https://doi.org/10.1016/j.clay.2006.11.008

Lazarević S, Janković-Častvan I, Jovanović D, Milonjić SK, Janaćković Đ, Petrović R. Adsorption of Pb2+, Cd2+ and Sr2+ ions onto natural and acid-activated sepiolites. in Applied Clay Science. 2007;37(1-2):47-57.
doi:10.1016/j.clay.2006.11.008 .

Lazarević, Slavica, Janković-Častvan, Ivona, Jovanović, Dušan, Milonjić, Slobodan K., Janaćković, Đorđe, Petrović, Rada, "Adsorption of Pb2+, Cd2+ and Sr2+ ions onto natural and acid-activated sepiolites" in Applied Clay Science, 37, no. 1-2 (2007):47-57,
https://doi.org/10.1016/j.clay.2006.11.008 . .