TY  - JOUR
AU  - Tadić, Marin
AU  - Panjan, Matjaž
AU  - Vučetić Tadić, Biljana
AU  - Lazović, Jelena
AU  - Damnjanović, Vesna
AU  - Kopani, Martin
AU  - Kopanja, Lazar
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5897
AB  - Using the sol-gel method we synthesized hematite (α - Fe2O3) nanoparticles in a silica matrix with 60 wt % of hematite. X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra of the sample demonstrate the formation of the α - Fe2O3 phase and amorphous silica. A transmission electron microscopy (TEM) measurements show that the sample consists of two particle size distributions of the hematite nanoparticles with average sizes around 10 nm and 20 nm, respectively. Magnetic properties of hematite nanoparticles were measured using a superconducting quantum interference device (SQUID). Investigation of the magnetic properties of hematite nanoparticles showed a divergence between field-cooled (FC) and zero-field-cooled (ZFC) magnetization curves and two maxima. The ZFC magnetization curves displayed a maximum at around TB = 50 K (blocking temperature) and at TM = 83 K (the Morin transition). The hysteresis loop measured at 5 K was symmetric around the origin, with the values of coercivity, remanent and mass saturation magnetization HC10K ≈ 646 A/cm, (810 Oe), Mr10K = 1.34 emu/g and MS10K = 6.1 emu/g respectively. The absence of both coercivity (HC300K = 0) and remanent magnetization (Mr300K = 0) in M(H) curve at 300 K reveals super-paramagnetic behavior, which is desirable for application in biomedicine. The bimodal particle size distributions were used to describe observed magnetic properties of hematite nanoparticles. The size distribution directly influences the magnetic properties of the sample.
PB  - De Gruyter Open Ltd
T2  - Journal of Electrical Engineering
T1  - Magnetic properties of hematite (α - Fe2O3) nanoparticles synthesized by sol-gel synthesis method: The influence of particle size and particle size distribution
EP  - 76
IS  - 7
SP  - 71
VL  - 70
DO  - 10.2478/jee-2019-0044
ER  - 

@article{
author = "Tadić, Marin and Panjan, Matjaž and Vučetić Tadić, Biljana and Lazović, Jelena and Damnjanović, Vesna and Kopani, Martin and Kopanja, Lazar",
year = "2019",
abstract = "Using the sol-gel method we synthesized hematite (α - Fe2O3) nanoparticles in a silica matrix with 60 wt % of hematite. X-ray diffraction (XRD) patterns and Fourier transform infrared (FTIR) spectra of the sample demonstrate the formation of the α - Fe2O3 phase and amorphous silica. A transmission electron microscopy (TEM) measurements show that the sample consists of two particle size distributions of the hematite nanoparticles with average sizes around 10 nm and 20 nm, respectively. Magnetic properties of hematite nanoparticles were measured using a superconducting quantum interference device (SQUID). Investigation of the magnetic properties of hematite nanoparticles showed a divergence between field-cooled (FC) and zero-field-cooled (ZFC) magnetization curves and two maxima. The ZFC magnetization curves displayed a maximum at around TB = 50 K (blocking temperature) and at TM = 83 K (the Morin transition). The hysteresis loop measured at 5 K was symmetric around the origin, with the values of coercivity, remanent and mass saturation magnetization HC10K ≈ 646 A/cm, (810 Oe), Mr10K = 1.34 emu/g and MS10K = 6.1 emu/g respectively. The absence of both coercivity (HC300K = 0) and remanent magnetization (Mr300K = 0) in M(H) curve at 300 K reveals super-paramagnetic behavior, which is desirable for application in biomedicine. The bimodal particle size distributions were used to describe observed magnetic properties of hematite nanoparticles. The size distribution directly influences the magnetic properties of the sample.",
publisher = "De Gruyter Open Ltd",
journal = "Journal of Electrical Engineering",
title = "Magnetic properties of hematite (α - Fe2O3) nanoparticles synthesized by sol-gel synthesis method: The influence of particle size and particle size distribution",
pages = "76-71",
number = "7",
volume = "70",
doi = "10.2478/jee-2019-0044"
}

Tadić, M., Panjan, M., Vučetić Tadić, B., Lazović, J., Damnjanović, V., Kopani, M.,& Kopanja, L.. (2019). Magnetic properties of hematite (α - Fe2O3) nanoparticles synthesized by sol-gel synthesis method: The influence of particle size and particle size distribution. in Journal of Electrical Engineering
De Gruyter Open Ltd., 70(7), 71-76.
https://doi.org/10.2478/jee-2019-0044

Tadić M, Panjan M, Vučetić Tadić B, Lazović J, Damnjanović V, Kopani M, Kopanja L. Magnetic properties of hematite (α - Fe2O3) nanoparticles synthesized by sol-gel synthesis method: The influence of particle size and particle size distribution. in Journal of Electrical Engineering. 2019;70(7):71-76.
doi:10.2478/jee-2019-0044 .

Tadić, Marin, Panjan, Matjaž, Vučetić Tadić, Biljana, Lazović, Jelena, Damnjanović, Vesna, Kopani, Martin, Kopanja, Lazar, "Magnetic properties of hematite (α - Fe2O3) nanoparticles synthesized by sol-gel synthesis method: The influence of particle size and particle size distribution" in Journal of Electrical Engineering, 70, no. 7 (2019):71-76,
https://doi.org/10.2478/jee-2019-0044 . .

TY  - JOUR
AU  - Tadić, Marin
AU  - Trpkov, Đorđe
AU  - Kopanja, Lazar
AU  - Vojnović, Sandra
AU  - Panjan, Matjaž
PY  - 2019
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5892
AB  - In this work, we present the magnetic and structural properties of α-Fe 2 O 3 nanoparticles synthesized by the hydrothermal synthesis method. XRD, FTIR and Raman spectroscopy indicate that the samples consist of single-phase α-Fe 2 O 3 nanoparticles. A microstructural analysis by TEM and SEM shows: (i) irregular nanoparticles (∼50 nm), (ii) plate-like nanoparticles (with thickness t∼10 nm and diameter d∼50–80 nm) and (iii) microsized ellipsoid 3D superstructures (with length l∼3.5 and diameter d∼1.5 μm) composed of nanosized building blocks (∼50 nm). We used circularity, elongation and convexity measures to quantitatively analyze the shape of the particles. Irregular hematite nanoparticles were synthesized using a water solution of ferric precursor and sodium acetate during the hydrothermal reaction (reaction conditions: T = 180 °C, t = 12 h). The same hydrothermal reaction temperature, reaction duration and ferric precursor (without sodium acetate) were used for synthesizing hematite ellipsoid 3D superstructures. Addition of urea and glycine surfactants in hydrothermal reaction resulted in the formation of nanoplate hematite particles. The role of these surfactants on the structure and morphology of the particles was also investigated. Magnetic measurements at the room temperature displayed a wide range of coercivities, from H C = 73 Oe for irregular nanoparticles, H C = 689 Oe for nanoplates to H C = 2688 Oe for hematite ellipsoid 3D superstructures. The measured coercivity for the ellipsoid superstructure was about 35 times higher than in the case of irregular hematite nanoparticles and about 4 times than the coercivity of hematite nanoplates. Magnetic properties of synthesized samples were related to their structure and morphology. We conclude that shape anisotropy influenced enhancement of the coercivity in hematite nanoplates whereas hematite ellipsoid 3D superstructure (nanoparticle clusters) induced the formation of multidomain magnetic structure and highest coercivity revealing its superior structure for enhanced magnetic properties. The synthesized hematite nanoparticle structures exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating a safe use of these nanoparticles for practical applications. © 2019 Elsevier B.V.
T2  - Journal of Alloys and Compounds
T1  - Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties
EP  - 609
SP  - 599
VL  - 792
DO  - 10.1016/j.jallcom.2019.03.414
ER  - 

@article{
author = "Tadić, Marin and Trpkov, Đorđe and Kopanja, Lazar and Vojnović, Sandra and Panjan, Matjaž",
year = "2019",
abstract = "In this work, we present the magnetic and structural properties of α-Fe 2 O 3 nanoparticles synthesized by the hydrothermal synthesis method. XRD, FTIR and Raman spectroscopy indicate that the samples consist of single-phase α-Fe 2 O 3 nanoparticles. A microstructural analysis by TEM and SEM shows: (i) irregular nanoparticles (∼50 nm), (ii) plate-like nanoparticles (with thickness t∼10 nm and diameter d∼50–80 nm) and (iii) microsized ellipsoid 3D superstructures (with length l∼3.5 and diameter d∼1.5 μm) composed of nanosized building blocks (∼50 nm). We used circularity, elongation and convexity measures to quantitatively analyze the shape of the particles. Irregular hematite nanoparticles were synthesized using a water solution of ferric precursor and sodium acetate during the hydrothermal reaction (reaction conditions: T = 180 °C, t = 12 h). The same hydrothermal reaction temperature, reaction duration and ferric precursor (without sodium acetate) were used for synthesizing hematite ellipsoid 3D superstructures. Addition of urea and glycine surfactants in hydrothermal reaction resulted in the formation of nanoplate hematite particles. The role of these surfactants on the structure and morphology of the particles was also investigated. Magnetic measurements at the room temperature displayed a wide range of coercivities, from H C = 73 Oe for irregular nanoparticles, H C = 689 Oe for nanoplates to H C = 2688 Oe for hematite ellipsoid 3D superstructures. The measured coercivity for the ellipsoid superstructure was about 35 times higher than in the case of irregular hematite nanoparticles and about 4 times than the coercivity of hematite nanoplates. Magnetic properties of synthesized samples were related to their structure and morphology. We conclude that shape anisotropy influenced enhancement of the coercivity in hematite nanoplates whereas hematite ellipsoid 3D superstructure (nanoparticle clusters) induced the formation of multidomain magnetic structure and highest coercivity revealing its superior structure for enhanced magnetic properties. The synthesized hematite nanoparticle structures exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating a safe use of these nanoparticles for practical applications. © 2019 Elsevier B.V.",
journal = "Journal of Alloys and Compounds",
title = "Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties",
pages = "609-599",
volume = "792",
doi = "10.1016/j.jallcom.2019.03.414"
}

Tadić, M., Trpkov, Đ., Kopanja, L., Vojnović, S.,& Panjan, M.. (2019). Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties. in Journal of Alloys and Compounds, 792, 599-609.
https://doi.org/10.1016/j.jallcom.2019.03.414

Tadić M, Trpkov Đ, Kopanja L, Vojnović S, Panjan M. Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties. in Journal of Alloys and Compounds. 2019;792:599-609.
doi:10.1016/j.jallcom.2019.03.414 .

Tadić, Marin, Trpkov, Đorđe, Kopanja, Lazar, Vojnović, Sandra, Panjan, Matjaž, "Hydrothermal synthesis of hematite (α-Fe2O3) nanoparticle forms: Synthesis conditions, structure, particle shape analysis, cytotoxicity and magnetic properties" in Journal of Alloys and Compounds, 792 (2019):599-609,
https://doi.org/10.1016/j.jallcom.2019.03.414 . .

TY  - JOUR
AU  - Trpkov, Đorđe
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Tadić, Marin
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5874
AB  - We report on glycine-free and glycine-assisted hydrothermal synthesis of microsized superstructures composed of self-assembled hematite nanoparticles. An X-ray powder diffraction measurements of the samples confirm good crystallization of the hematite nanoparticles with hydrothermal reaction time-dependent crystallite sizes in a range from ∼15 nm (45 h) to ∼26 nm (90 h). The FTIR and Raman spectroscopy confirm hematite structure, whereas TEM measurements reveal nanoparticle sub-units (subparticles). The computational analyses of particle shape show that the addition of glycine surfactant in hydrothermal reaction leads to more spherical shape of hematite hierarchical structures and smaller sizes. We found strong coercivity increases (up to ∼3 times) in the samples synthesized in the presence of glycine. The coercivity values from HC = 1305 Oe (mushroom-like shape synthesized by glycine-free hydrothermal reaction) to HC = 3725 Oe (sphere-like shape synthesized by glycine-assisted hydrothermal reaction) were obtained at 300 K. These results and their comparison with other described in the literature (e.g. bulk, wires, urchin-like, rods, tubes, plates, star-like, dendrites, platelets, irregular, nanocolumns, spindles, disks hematites, etc.) reveal that the hematite superstructures possess good magnetic properties. We propose that the glycine, oriented subparticles, exchange and dipole-dipole interactions may play an important role in the development of magnetic properties.
T2  - Applied Surface Science
T1  - Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures
EP  - 438
SP  - 427
VL  - 457
DO  - 10.1016/j.apsusc.2018.06.224
ER  - 

@article{
author = "Trpkov, Đorđe and Panjan, Matjaž and Kopanja, Lazar and Tadić, Marin",
year = "2018",
abstract = "We report on glycine-free and glycine-assisted hydrothermal synthesis of microsized superstructures composed of self-assembled hematite nanoparticles. An X-ray powder diffraction measurements of the samples confirm good crystallization of the hematite nanoparticles with hydrothermal reaction time-dependent crystallite sizes in a range from ∼15 nm (45 h) to ∼26 nm (90 h). The FTIR and Raman spectroscopy confirm hematite structure, whereas TEM measurements reveal nanoparticle sub-units (subparticles). The computational analyses of particle shape show that the addition of glycine surfactant in hydrothermal reaction leads to more spherical shape of hematite hierarchical structures and smaller sizes. We found strong coercivity increases (up to ∼3 times) in the samples synthesized in the presence of glycine. The coercivity values from HC = 1305 Oe (mushroom-like shape synthesized by glycine-free hydrothermal reaction) to HC = 3725 Oe (sphere-like shape synthesized by glycine-assisted hydrothermal reaction) were obtained at 300 K. These results and their comparison with other described in the literature (e.g. bulk, wires, urchin-like, rods, tubes, plates, star-like, dendrites, platelets, irregular, nanocolumns, spindles, disks hematites, etc.) reveal that the hematite superstructures possess good magnetic properties. We propose that the glycine, oriented subparticles, exchange and dipole-dipole interactions may play an important role in the development of magnetic properties.",
journal = "Applied Surface Science",
title = "Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures",
pages = "438-427",
volume = "457",
doi = "10.1016/j.apsusc.2018.06.224"
}

Trpkov, Đ., Panjan, M., Kopanja, L.,& Tadić, M.. (2018). Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures. in Applied Surface Science, 457, 427-438.
https://doi.org/10.1016/j.apsusc.2018.06.224

Trpkov Đ, Panjan M, Kopanja L, Tadić M. Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures. in Applied Surface Science. 2018;457:427-438.
doi:10.1016/j.apsusc.2018.06.224 .

Trpkov, Đorđe, Panjan, Matjaž, Kopanja, Lazar, Tadić, Marin, "Hydrothermal synthesis, morphology, magnetic properties and self-assembly of hierarchical α-Fe2O3 (hematite) mushroom-, cube- and sphere-like superstructures" in Applied Surface Science, 457 (2018):427-438,
https://doi.org/10.1016/j.apsusc.2018.06.224 . .

TY  - JOUR
AU  - Tadić, Marin
AU  - Kopanja, Lazar
AU  - Panjan, Matjaž
AU  - Kralj, Slavko
AU  - Nikodinović Runić, Jasmina
AU  - Stojanović, Zoran S.
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5854
AB  - Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase α-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10–20 nm thickness, 80–100 nm landscape dimensions (aspect ratio ∼5) and 3–4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core–shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity HC = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles’ for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications.
T2  - Applied Surface Science
T1  - Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity
EP  - 634
SP  - 628
VL  - 403
DO  - 10.1016/j.apsusc.2017.01.115
UR  - https://hdl.handle.net/21.15107/rcub_dais_2349
ER  - 

@article{
author = "Tadić, Marin and Kopanja, Lazar and Panjan, Matjaž and Kralj, Slavko and Nikodinović Runić, Jasmina and Stojanović, Zoran S.",
year = "2017",
abstract = "Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase α-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10–20 nm thickness, 80–100 nm landscape dimensions (aspect ratio ∼5) and 3–4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core–shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity HC = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles’ for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications.",
journal = "Applied Surface Science",
title = "Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity",
pages = "634-628",
volume = "403",
doi = "10.1016/j.apsusc.2017.01.115",
url = "https://hdl.handle.net/21.15107/rcub_dais_2349"
}

Tadić, M., Kopanja, L., Panjan, M., Kralj, S., Nikodinović Runić, J.,& Stojanović, Z. S.. (2017). Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity. in Applied Surface Science, 403, 628-634.
https://doi.org/10.1016/j.apsusc.2017.01.115
https://hdl.handle.net/21.15107/rcub_dais_2349

Tadić M, Kopanja L, Panjan M, Kralj S, Nikodinović Runić J, Stojanović ZS. Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity. in Applied Surface Science. 2017;403:628-634.
doi:10.1016/j.apsusc.2017.01.115
https://hdl.handle.net/21.15107/rcub_dais_2349 .

Tadić, Marin, Kopanja, Lazar, Panjan, Matjaž, Kralj, Slavko, Nikodinović Runić, Jasmina, Stojanović, Zoran S., "Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity" in Applied Surface Science, 403 (2017):628-634,
https://doi.org/10.1016/j.apsusc.2017.01.115 .,
https://hdl.handle.net/21.15107/rcub_dais_2349 .

TY  - JOUR
AU  - Nikolić, Violeta N.
AU  - Spasojević, Vojislav
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Mraković, Ana Đ.
AU  - Tadić, Marin
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5852
AB  - Several Fe2O3/SiO2 nanostructures were synthesized by the combination of the microemulsion and a sol-gel methods. Based on X-ray powder diffraction (XRD) and magnetic measurements (giant coercivity similar to 2.13 T) we identified epsilon-Fe2O3 (hard magnet) as the dominant crystalline phase. TEM analysis showed a wide size distribution of iron oxide nanoparticles (from 4 to 50 nm) with various morphologies (spherical, ellipsoidal and rod-like). We quantitatively described (computational analysis, MATLAB code) morphological properties of nanoparticles using the ellipticity of the shapes. The as-synthesized hard magnetic material was subjected to a post-annealing treatment at different temperatures (200, 500, 750, 1000 and 1100 degrees C) in order to investigate stability, formation and transformation of the epsilon-Fe2O3 polymorph. We found decreasing coercivity in the thermally treated samples up to the temperature of 750 degrees C (H-c=1245 Oe), followed by an observation of a surprising jump in coercivity H-c similar to 1.5 T after post-annealing at 1000 degrees C. We conclude that the re-formation of the epsilon-Fe2O3 structure during post-annealing at 1000 degrees C is the origin of the observed phenomena. The phase transformation epsilon-Fe2O3 - GT alpha-Fe2O3 and crystallization of amorphous silica in quartz and cristobalite were observed in the sample treated at 1100 degrees C.
T2  - Ceramics International
T1  - Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties
EP  - 7507
IS  - 10
SP  - 7497
VL  - 43
DO  - 10.1016/j.ceramint.2017.03.030
ER  - 

@article{
author = "Nikolić, Violeta N. and Spasojević, Vojislav and Panjan, Matjaž and Kopanja, Lazar and Mraković, Ana Đ. and Tadić, Marin",
year = "2017",
abstract = "Several Fe2O3/SiO2 nanostructures were synthesized by the combination of the microemulsion and a sol-gel methods. Based on X-ray powder diffraction (XRD) and magnetic measurements (giant coercivity similar to 2.13 T) we identified epsilon-Fe2O3 (hard magnet) as the dominant crystalline phase. TEM analysis showed a wide size distribution of iron oxide nanoparticles (from 4 to 50 nm) with various morphologies (spherical, ellipsoidal and rod-like). We quantitatively described (computational analysis, MATLAB code) morphological properties of nanoparticles using the ellipticity of the shapes. The as-synthesized hard magnetic material was subjected to a post-annealing treatment at different temperatures (200, 500, 750, 1000 and 1100 degrees C) in order to investigate stability, formation and transformation of the epsilon-Fe2O3 polymorph. We found decreasing coercivity in the thermally treated samples up to the temperature of 750 degrees C (H-c=1245 Oe), followed by an observation of a surprising jump in coercivity H-c similar to 1.5 T after post-annealing at 1000 degrees C. We conclude that the re-formation of the epsilon-Fe2O3 structure during post-annealing at 1000 degrees C is the origin of the observed phenomena. The phase transformation epsilon-Fe2O3 - GT alpha-Fe2O3 and crystallization of amorphous silica in quartz and cristobalite were observed in the sample treated at 1100 degrees C.",
journal = "Ceramics International",
title = "Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties",
pages = "7507-7497",
number = "10",
volume = "43",
doi = "10.1016/j.ceramint.2017.03.030"
}

Nikolić, V. N., Spasojević, V., Panjan, M., Kopanja, L., Mraković, A. Đ.,& Tadić, M.. (2017). Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties. in Ceramics International, 43(10), 7497-7507.
https://doi.org/10.1016/j.ceramint.2017.03.030

Nikolić VN, Spasojević V, Panjan M, Kopanja L, Mraković AĐ, Tadić M. Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties. in Ceramics International. 2017;43(10):7497-7507.
doi:10.1016/j.ceramint.2017.03.030 .

Nikolić, Violeta N., Spasojević, Vojislav, Panjan, Matjaž, Kopanja, Lazar, Mraković, Ana Đ., Tadić, Marin, "Re-formation of metastable epsilon-Fe2O3 in post-annealing of Fe2O3/SiO2 nanostructure: Synthesis, computational particle shape analysis in micrographs and magnetic properties" in Ceramics International, 43, no. 10 (2017):7497-7507,
https://doi.org/10.1016/j.ceramint.2017.03.030 . .

TY  - JOUR
AU  - Nikolić, Violeta N.
AU  - Tadić, Marin
AU  - Panjan, Matjaž
AU  - Kopanja, Lazar
AU  - Cvjetićanin, Nikola
AU  - Spasojević, Vojislav
PY  - 2017
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5822
AB  - Magnetic properties of Fe2O3/SiO2 samples were studied after being produced by sol-gel synthesis and formation of epsilon-Fe2O3 polymorph. Samples were thermally treated, using different annealing temperatures and annealing times. The size and morphological characteristics of the iron oxide nanoparticles were examined using a TEM microscope. We used the ellipticity of shapes, which is a measure of how much the shape of a nanoparticle differs from a perfect ellipse, in order to quantitatively describe morphological properties of nanoparticles. Coercivity measurements were used to identify and monitor the formation of the epsilon-iron oxide phase during the thermal treatments (annealing). Coercivity values were in the range from 1.2 to 15.4 kOe, which is in accordance with previous experience regarding the existence of epsilon-Fe2O3. We have determined the optimal formation conditions for the epsilon-Fe2O3 polymorph (t=1050 degrees C for 7 h, H-c=15.4 kOe), as well as the narrow temperature interval (1050-1060 C) in which the polymorph abruptly vanished (H-c=2300 Oe), on the basis of results of the magnetic properties. The threshold temperature for the epsilon-Fe2O3 phase transformation was measured as 1060 degrees C. We found that different annealing temperatures and annealing times significantly affected magnetic properties of the examined samples.
T2  - Ceramics International
T1  - Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase
EP  - 3155
IS  - 3
SP  - 3147
VL  - 43
DO  - 10.1016/j.ceramint.2016.11.132
ER  - 

@article{
author = "Nikolić, Violeta N. and Tadić, Marin and Panjan, Matjaž and Kopanja, Lazar and Cvjetićanin, Nikola and Spasojević, Vojislav",
year = "2017",
abstract = "Magnetic properties of Fe2O3/SiO2 samples were studied after being produced by sol-gel synthesis and formation of epsilon-Fe2O3 polymorph. Samples were thermally treated, using different annealing temperatures and annealing times. The size and morphological characteristics of the iron oxide nanoparticles were examined using a TEM microscope. We used the ellipticity of shapes, which is a measure of how much the shape of a nanoparticle differs from a perfect ellipse, in order to quantitatively describe morphological properties of nanoparticles. Coercivity measurements were used to identify and monitor the formation of the epsilon-iron oxide phase during the thermal treatments (annealing). Coercivity values were in the range from 1.2 to 15.4 kOe, which is in accordance with previous experience regarding the existence of epsilon-Fe2O3. We have determined the optimal formation conditions for the epsilon-Fe2O3 polymorph (t=1050 degrees C for 7 h, H-c=15.4 kOe), as well as the narrow temperature interval (1050-1060 C) in which the polymorph abruptly vanished (H-c=2300 Oe), on the basis of results of the magnetic properties. The threshold temperature for the epsilon-Fe2O3 phase transformation was measured as 1060 degrees C. We found that different annealing temperatures and annealing times significantly affected magnetic properties of the examined samples.",
journal = "Ceramics International",
title = "Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase",
pages = "3155-3147",
number = "3",
volume = "43",
doi = "10.1016/j.ceramint.2016.11.132"
}

Nikolić, V. N., Tadić, M., Panjan, M., Kopanja, L., Cvjetićanin, N.,& Spasojević, V.. (2017). Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase. in Ceramics International, 43(3), 3147-3155.
https://doi.org/10.1016/j.ceramint.2016.11.132

Nikolić VN, Tadić M, Panjan M, Kopanja L, Cvjetićanin N, Spasojević V. Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase. in Ceramics International. 2017;43(3):3147-3155.
doi:10.1016/j.ceramint.2016.11.132 .

Nikolić, Violeta N., Tadić, Marin, Panjan, Matjaž, Kopanja, Lazar, Cvjetićanin, Nikola, Spasojević, Vojislav, "Influence of annealing treatment on magnetic properties of Fe2O3/SiO2 and formation of epsilon-Fe2O3 phase" in Ceramics International, 43, no. 3 (2017):3147-3155,
https://doi.org/10.1016/j.ceramint.2016.11.132 . .