TY  - JOUR
AU  - Krsmanović, Radenka
AU  - Antić, Željka
AU  - Milićević, Bojana R.
AU  - Pošarac-Marković, Milica B.
AU  - Janaćković, Đorđe
AU  - Dramićanin, Miroslav
AU  - Brik, Mikhail G.
AU  - Steins, Ints
AU  - Veljović, Đorđe
PY  - 2014
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2857
AB  - Using Spark Plasma Sintering it is possible to produce polycrystalline ceramics of very fine microstructure and good mechanical properties. This work presents the fabrication of such ceramics using Eu3+-doped (Y0.7Gd0.3)(2)O-3 nanopowder as a starting material. We monitored the changes in the morphology of ceramic samples and their consolidation with additional thermal treatments at 650 degrees C and 1100 degrees C. The ceramics grain size remained in the sub-micron domain, even when elevated temperatures were used for annealing. The best results were obtained for the sample sintered at 1100 degrees C for 20 min, which had the smallest grain size, theoretical density, and the most intensive photoluminescence, along with the maximum hardness and appropriate fracture toughness. The Judd-Ofelt intensity parameters and branching ratios were calculated, taking into account the difference in the effective refractive index for the nanopowder and ceramic samples.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development
EP  - 8862
IS  - 6
SP  - 8853
VL  - 40
DO  - 10.1016/j.ceramint.2014.01.108
ER  - 

@article{
author = "Krsmanović, Radenka and Antić, Željka and Milićević, Bojana R. and Pošarac-Marković, Milica B. and Janaćković, Đorđe and Dramićanin, Miroslav and Brik, Mikhail G. and Steins, Ints and Veljović, Đorđe",
year = "2014",
abstract = "Using Spark Plasma Sintering it is possible to produce polycrystalline ceramics of very fine microstructure and good mechanical properties. This work presents the fabrication of such ceramics using Eu3+-doped (Y0.7Gd0.3)(2)O-3 nanopowder as a starting material. We monitored the changes in the morphology of ceramic samples and their consolidation with additional thermal treatments at 650 degrees C and 1100 degrees C. The ceramics grain size remained in the sub-micron domain, even when elevated temperatures were used for annealing. The best results were obtained for the sample sintered at 1100 degrees C for 20 min, which had the smallest grain size, theoretical density, and the most intensive photoluminescence, along with the maximum hardness and appropriate fracture toughness. The Judd-Ofelt intensity parameters and branching ratios were calculated, taking into account the difference in the effective refractive index for the nanopowder and ceramic samples.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development",
pages = "8862-8853",
number = "6",
volume = "40",
doi = "10.1016/j.ceramint.2014.01.108"
}

Krsmanović, R., Antić, Ž., Milićević, B. R., Pošarac-Marković, M. B., Janaćković, Đ., Dramićanin, M., Brik, M. G., Steins, I.,& Veljović, Đ.. (2014). Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development. in Ceramics International
Elsevier Sci Ltd, Oxford., 40(6), 8853-8862.
https://doi.org/10.1016/j.ceramint.2014.01.108

Krsmanović R, Antić Ž, Milićević BR, Pošarac-Marković MB, Janaćković Đ, Dramićanin M, Brik MG, Steins I, Veljović Đ. Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development. in Ceramics International. 2014;40(6):8853-8862.
doi:10.1016/j.ceramint.2014.01.108 .

Krsmanović, Radenka, Antić, Željka, Milićević, Bojana R., Pošarac-Marković, Milica B., Janaćković, Đorđe, Dramićanin, Miroslav, Brik, Mikhail G., Steins, Ints, Veljović, Đorđe, "Polycrystalline (Y0.7Gd0.3)(2)O-3:Eu3+ ceramics fabricated by Spark Plasma Sintering: Densification and microstructure development" in Ceramics International, 40, no. 6 (2014):8853-8862,
https://doi.org/10.1016/j.ceramint.2014.01.108 . .

TY  - JOUR
AU  - El-Buaishi, Nozhat Moftah
AU  - Veljović, Đorđe
AU  - Jokić, Bojan
AU  - Radovanović, Željko
AU  - Steins, Ints
AU  - Janaćković, Đorđe
AU  - Petrović, Rada
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2531
AB  - Cordierite powders synthesized by colloidal and alkoxide sol-gel methods were conventionally and spark-plasma sintered. The powders for the sintering investigations were obtained by calcination of the gels at a temperature where alpha-cordierite is formed (crystalline powders) or at a temperature where densification without crystallization of silica-containing component occurred (amorphous powders). All the calcinated gels were ground for 3 h, uniaxial pressed at 400 MPa and sintered conventionally at 1400, 1430 and 1450 degrees C for 2 h. In order to improve the sintering behavior of the cordierite powders, spark-plasma sintering (SPS) was applied. The microstructures and the phase composition of the obtained cordierite materials were analyzed using scanning electron microscopy (SEM) and X-ray diffraction analysis and the mechanical properties of the materials were determined. It was shown that the sinterability of the colloidal powders was much better than that of the alkoxide powders. Conventional sintering at 1400 degrees C of the crystalline powder produced by the colloidal method gave the material of the best mechanical properties. The sinterability of the crystalline alkoxide cordierite powder was highly improved by spark-plasma sintering at a lower sintering temperature (1350 degrees C), for a very short period of tithe (7 min). The density of the obtained material was very close to the theoretical density of alpha-cordierite and the mechanical properties were better than those of materials obtained by conventional sintering.
PB  - Elsevier Sci Ltd, Oxford
T2  - Ceramics International
T1  - Conventional and spark-plasma sintering of cordierite powders synthesized by sol-gel methods
EP  - 5854
IS  - 5
SP  - 5845
VL  - 39
DO  - 10.1016/j.ceramint.2012.12.101
ER  - 

@article{
author = "El-Buaishi, Nozhat Moftah and Veljović, Đorđe and Jokić, Bojan and Radovanović, Željko and Steins, Ints and Janaćković, Đorđe and Petrović, Rada",
year = "2013",
abstract = "Cordierite powders synthesized by colloidal and alkoxide sol-gel methods were conventionally and spark-plasma sintered. The powders for the sintering investigations were obtained by calcination of the gels at a temperature where alpha-cordierite is formed (crystalline powders) or at a temperature where densification without crystallization of silica-containing component occurred (amorphous powders). All the calcinated gels were ground for 3 h, uniaxial pressed at 400 MPa and sintered conventionally at 1400, 1430 and 1450 degrees C for 2 h. In order to improve the sintering behavior of the cordierite powders, spark-plasma sintering (SPS) was applied. The microstructures and the phase composition of the obtained cordierite materials were analyzed using scanning electron microscopy (SEM) and X-ray diffraction analysis and the mechanical properties of the materials were determined. It was shown that the sinterability of the colloidal powders was much better than that of the alkoxide powders. Conventional sintering at 1400 degrees C of the crystalline powder produced by the colloidal method gave the material of the best mechanical properties. The sinterability of the crystalline alkoxide cordierite powder was highly improved by spark-plasma sintering at a lower sintering temperature (1350 degrees C), for a very short period of tithe (7 min). The density of the obtained material was very close to the theoretical density of alpha-cordierite and the mechanical properties were better than those of materials obtained by conventional sintering.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Ceramics International",
title = "Conventional and spark-plasma sintering of cordierite powders synthesized by sol-gel methods",
pages = "5854-5845",
number = "5",
volume = "39",
doi = "10.1016/j.ceramint.2012.12.101"
}

El-Buaishi, N. M., Veljović, Đ., Jokić, B., Radovanović, Ž., Steins, I., Janaćković, Đ.,& Petrović, R.. (2013). Conventional and spark-plasma sintering of cordierite powders synthesized by sol-gel methods. in Ceramics International
Elsevier Sci Ltd, Oxford., 39(5), 5845-5854.
https://doi.org/10.1016/j.ceramint.2012.12.101

El-Buaishi NM, Veljović Đ, Jokić B, Radovanović Ž, Steins I, Janaćković Đ, Petrović R. Conventional and spark-plasma sintering of cordierite powders synthesized by sol-gel methods. in Ceramics International. 2013;39(5):5845-5854.
doi:10.1016/j.ceramint.2012.12.101 .

El-Buaishi, Nozhat Moftah, Veljović, Đorđe, Jokić, Bojan, Radovanović, Željko, Steins, Ints, Janaćković, Đorđe, Petrović, Rada, "Conventional and spark-plasma sintering of cordierite powders synthesized by sol-gel methods" in Ceramics International, 39, no. 5 (2013):5845-5854,
https://doi.org/10.1016/j.ceramint.2012.12.101 . .

TY  - JOUR
AU  - Veljović, Đorđe
AU  - Vuković, Goran D.
AU  - Steins, Ints
AU  - Palcevskis, Eriks
AU  - Uskoković, Petar
AU  - Petrović, Rada
AU  - Janaćković, Đorđe
PY  - 2013
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/2299
AB  - Composites based on HAP and oxidized multi-walled carbon nanotubes (o-MWCNT) and monophase HAP materials were processed by spark plasma sintering. Starting from stoichiometric nano-sized HAP powder, monophase bioceramics were obtained with a density close to the theoretical one and with an average grain size of several hundred nanometers to micron dimensions. It was shown that decreasing the sintering temperature resulted in a decrease of the grain size, which affected an increase in the fracture toughness and hardness. The fracture toughness of an HAP/ o-MWCNT bioceramic processed at 900°C for only 5 min was 30 % higher than that of monophase HAP materials obtained under the same conditions. The addition of MWCNT during SPS processing of HAP materials caused a decrease in the grain size to the nano-dimension, which was one of the reasons for the improved mechanical properties.
AB  - Kompoziti na bazi hidroksiapatita i oksidovanih višeslojnih karbonskih nanotuba i monofazni hidroksiapatitni materijali dobijeni su spark plazma sinterovanjem. Polazeći od stehiometrijskog nanočestičnog praha hidroksiapatita, dobijeni su monofazni hidroksiapatitni biokeramički materijali sa gustinama bliskim teorijskim vrednostima i prosečnom veličinom zrna od nekoliko stotina nanometara do mikronskih dimenzija. Pokazano je da se sa smanjenjem temperature sinterovanja smanjuje prosečna veličina zrna, što utiče na povećanje žilavosti i tvrdoće materijala. Žilavost kompozitnog biokeramičkog materijala dobijenog na 900°C za svega 5 minuta bila je 30 % veća od žilavosti monofazne hidroksiapatitne biokeramike dobijene pri identičnim parametrima procesiranja. Dodatak oksidovanih karbonskih nanotuba tokom procesiranja spark plazma sinterovanjem, prouzrokovao je smanjenje veličine zrna na nono dimenzije, što je jedan od razloga za poboljšanje mehaničkih svojstava dobijenih materijala.
PB  - International Institute for the Science of Sintering, Beograd
T2  - Science of Sintering
T1  - Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes
EP  - 243
IS  - 2
SP  - 233
VL  - 45
UR  - https://hdl.handle.net/21.15107/rcub_technorep_2299
ER  - 

@article{
author = "Veljović, Đorđe and Vuković, Goran D. and Steins, Ints and Palcevskis, Eriks and Uskoković, Petar and Petrović, Rada and Janaćković, Đorđe",
year = "2013",
abstract = "Composites based on HAP and oxidized multi-walled carbon nanotubes (o-MWCNT) and monophase HAP materials were processed by spark plasma sintering. Starting from stoichiometric nano-sized HAP powder, monophase bioceramics were obtained with a density close to the theoretical one and with an average grain size of several hundred nanometers to micron dimensions. It was shown that decreasing the sintering temperature resulted in a decrease of the grain size, which affected an increase in the fracture toughness and hardness. The fracture toughness of an HAP/ o-MWCNT bioceramic processed at 900°C for only 5 min was 30 % higher than that of monophase HAP materials obtained under the same conditions. The addition of MWCNT during SPS processing of HAP materials caused a decrease in the grain size to the nano-dimension, which was one of the reasons for the improved mechanical properties., Kompoziti na bazi hidroksiapatita i oksidovanih višeslojnih karbonskih nanotuba i monofazni hidroksiapatitni materijali dobijeni su spark plazma sinterovanjem. Polazeći od stehiometrijskog nanočestičnog praha hidroksiapatita, dobijeni su monofazni hidroksiapatitni biokeramički materijali sa gustinama bliskim teorijskim vrednostima i prosečnom veličinom zrna od nekoliko stotina nanometara do mikronskih dimenzija. Pokazano je da se sa smanjenjem temperature sinterovanja smanjuje prosečna veličina zrna, što utiče na povećanje žilavosti i tvrdoće materijala. Žilavost kompozitnog biokeramičkog materijala dobijenog na 900°C za svega 5 minuta bila je 30 % veća od žilavosti monofazne hidroksiapatitne biokeramike dobijene pri identičnim parametrima procesiranja. Dodatak oksidovanih karbonskih nanotuba tokom procesiranja spark plazma sinterovanjem, prouzrokovao je smanjenje veličine zrna na nono dimenzije, što je jedan od razloga za poboljšanje mehaničkih svojstava dobijenih materijala.",
publisher = "International Institute for the Science of Sintering, Beograd",
journal = "Science of Sintering",
title = "Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes",
pages = "243-233",
number = "2",
volume = "45",
url = "https://hdl.handle.net/21.15107/rcub_technorep_2299"
}

Veljović, Đ., Vuković, G. D., Steins, I., Palcevskis, E., Uskoković, P., Petrović, R.,& Janaćković, Đ.. (2013). Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes. in Science of Sintering
International Institute for the Science of Sintering, Beograd., 45(2), 233-243.
https://hdl.handle.net/21.15107/rcub_technorep_2299

Veljović Đ, Vuković GD, Steins I, Palcevskis E, Uskoković P, Petrović R, Janaćković Đ. Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes. in Science of Sintering. 2013;45(2):233-243.
https://hdl.handle.net/21.15107/rcub_technorep_2299 .

Veljović, Đorđe, Vuković, Goran D., Steins, Ints, Palcevskis, Eriks, Uskoković, Petar, Petrović, Rada, Janaćković, Đorđe, "Improvement of the mechanical properties of spark plasma sintered hap bioceramics by decreasing the grain size and by adding multi-walled carbon nanotubes" in Science of Sintering, 45, no. 2 (2013):233-243,
https://hdl.handle.net/21.15107/rcub_technorep_2299 .