TY  - JOUR
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Fahrenholtz, William
AU  - Smith, Steven
AU  - Mirković, Miljana M.
AU  - Peleš Tadić, Adriana
AU  - Petrović, Jovana
AU  - Đorđević, Antonije
PY  - 2024
UR  - https://dais.sanu.ac.rs/123456789/16383
AB  - Magnesium titanate ceramics were prepared by reactive spark plasma sintering (SPS) at 1200 °C for 5 min. Prior to sintering, MgO and TiO2 powders were mixed by high energy ball milling (HEBM) for 15, 30, or 60 min. The effect of milling time on phase composition was analyzed by X-ray diffraction (XRD) for milled powders and sintered specimens. The morphology of the sintered ceramics was investigated by scanning electron microscopy (SEM), while elemental distribution was determined by energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was detected in XRD and was confirmed by EDS analysis. Microcracking was observed for specimens prepared with longer milling times and attributed to the coefficient of thermal expansion (CTE) mismatch dominantly due to the anisotropic crystal structure of MgTiO3 phase. The sample milled for 15 min showed the highest Vickers hardness due to less or no microcracking and nearly full density. The dielectric measurements in the range of 10 Hz–250 MHz demonstrated extremely high dielectric permittivity, as high as 104 at 1 kHz. An increase in loss tangents was observed due to oxygen vacancy formation, which was promoted by the vacuum environment during SPS. Oxygen vacancy-related dielectric relaxation was also detected and explained.
T2  - Ceramics International
T1  - Spark plasma sintering of magnesium titanate ceramics
DO  - 10.1016/j.ceramint.2024.02.004
UR  - https://hdl.handle.net/21.15107/rcub_dais_16383
ER  - 

@article{
author = "Filipović, Suzana and Obradović, Nina and Fahrenholtz, William and Smith, Steven and Mirković, Miljana M. and Peleš Tadić, Adriana and Petrović, Jovana and Đorđević, Antonije",
year = "2024",
abstract = "Magnesium titanate ceramics were prepared by reactive spark plasma sintering (SPS) at 1200 °C for 5 min. Prior to sintering, MgO and TiO2 powders were mixed by high energy ball milling (HEBM) for 15, 30, or 60 min. The effect of milling time on phase composition was analyzed by X-ray diffraction (XRD) for milled powders and sintered specimens. The morphology of the sintered ceramics was investigated by scanning electron microscopy (SEM), while elemental distribution was determined by energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was detected in XRD and was confirmed by EDS analysis. Microcracking was observed for specimens prepared with longer milling times and attributed to the coefficient of thermal expansion (CTE) mismatch dominantly due to the anisotropic crystal structure of MgTiO3 phase. The sample milled for 15 min showed the highest Vickers hardness due to less or no microcracking and nearly full density. The dielectric measurements in the range of 10 Hz–250 MHz demonstrated extremely high dielectric permittivity, as high as 104 at 1 kHz. An increase in loss tangents was observed due to oxygen vacancy formation, which was promoted by the vacuum environment during SPS. Oxygen vacancy-related dielectric relaxation was also detected and explained.",
journal = "Ceramics International",
title = "Spark plasma sintering of magnesium titanate ceramics",
doi = "10.1016/j.ceramint.2024.02.004",
url = "https://hdl.handle.net/21.15107/rcub_dais_16383"
}

Filipović, S., Obradović, N., Fahrenholtz, W., Smith, S., Mirković, M. M., Peleš Tadić, A., Petrović, J.,& Đorđević, A.. (2024). Spark plasma sintering of magnesium titanate ceramics. in Ceramics International.
https://doi.org/10.1016/j.ceramint.2024.02.004
https://hdl.handle.net/21.15107/rcub_dais_16383

Filipović S, Obradović N, Fahrenholtz W, Smith S, Mirković MM, Peleš Tadić A, Petrović J, Đorđević A. Spark plasma sintering of magnesium titanate ceramics. in Ceramics International. 2024;.
doi:10.1016/j.ceramint.2024.02.004
https://hdl.handle.net/21.15107/rcub_dais_16383 .

Filipović, Suzana, Obradović, Nina, Fahrenholtz, William, Smith, Steven, Mirković, Miljana M., Peleš Tadić, Adriana, Petrović, Jovana, Đorđević, Antonije, "Spark plasma sintering of magnesium titanate ceramics" in Ceramics International (2024),
https://doi.org/10.1016/j.ceramint.2024.02.004 .,
https://hdl.handle.net/21.15107/rcub_dais_16383 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Smith, Steven
AU  - Obradović, Nina
AU  - Hilmas, Gregory E.
AU  - Fahrenholtz, William G.
PY  - 2023
UR  - https://dais.sanu.ac.rs/123456789/15224
AB  - High entropy carbide/boride (HEC/HEB) ceramics are materials with a wide range of possible applications in harsh environments due to their good mechanical properties, oxidation resistance, and thermal stability. They are usually formed by the solid solutioning of four or more transition metals (TM) in the boride and carbide lattice. In this research, boro/carbothermal reduction was used to form an individual diboride and carbide phases from oxide mixtures. The stoichiometry of the reaction was varied in order to synthesize pure dual phase ceramics. The reacted powders were spark plasma sintered (SPS) or hot pressed (HP), using a two-step process, to produce dense ceramics and to develop the solid solutions. Ceramics processed by SPS still contained residual oxides, while ceramics produced by HP were nominally phase-pure high entropy dual phase materials. Preferential segregation of the TMs was detected by energy dispersive spectroscopy. Vickers hardness measurements confirmed that the highest hardness was obtained for specimens densified by HP at 1950°C that contained no residual oxides and had the smallest grain size. The hardness increased from 25.7 ± 0.2 GPa to 33.6 ± 2.2 GPa with decrease applied load from 9.81N to 0.49N, respectively.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.
T1  - Optimization of processing parameters for high entropy dual phase ceramics
SP  - 53
EP  - 53
UR  - https://hdl.handle.net/21.15107/rcub_dais_15224
ER  - 

@conference{
author = "Filipović, Suzana and Smith, Steven and Obradović, Nina and Hilmas, Gregory E. and Fahrenholtz, William G.",
year = "2023",
abstract = "High entropy carbide/boride (HEC/HEB) ceramics are materials with a wide range of possible applications in harsh environments due to their good mechanical properties, oxidation resistance, and thermal stability. They are usually formed by the solid solutioning of four or more transition metals (TM) in the boride and carbide lattice. In this research, boro/carbothermal reduction was used to form an individual diboride and carbide phases from oxide mixtures. The stoichiometry of the reaction was varied in order to synthesize pure dual phase ceramics. The reacted powders were spark plasma sintered (SPS) or hot pressed (HP), using a two-step process, to produce dense ceramics and to develop the solid solutions. Ceramics processed by SPS still contained residual oxides, while ceramics produced by HP were nominally phase-pure high entropy dual phase materials. Preferential segregation of the TMs was detected by energy dispersive spectroscopy. Vickers hardness measurements confirmed that the highest hardness was obtained for specimens densified by HP at 1950°C that contained no residual oxides and had the smallest grain size. The hardness increased from 25.7 ± 0.2 GPa to 33.6 ± 2.2 GPa with decrease applied load from 9.81N to 0.49N, respectively.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.",
title = "Optimization of processing parameters for high entropy dual phase ceramics",
pages = "53-53",
url = "https://hdl.handle.net/21.15107/rcub_dais_15224"
}

Filipović, S., Smith, S., Obradović, N., Hilmas, G. E.,& Fahrenholtz, W. G.. (2023). Optimization of processing parameters for high entropy dual phase ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.
Belgrade : Serbian Ceramic Society., 53-53.
https://hdl.handle.net/21.15107/rcub_dais_15224

Filipović S, Smith S, Obradović N, Hilmas GE, Fahrenholtz WG. Optimization of processing parameters for high entropy dual phase ceramics. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023.. 2023;:53-53.
https://hdl.handle.net/21.15107/rcub_dais_15224 .

Filipović, Suzana, Smith, Steven, Obradović, Nina, Hilmas, Gregory E., Fahrenholtz, William G., "Optimization of processing parameters for high entropy dual phase ceramics" in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application XI New Frontiers in Multifunctional Material Science and Processing, Serbian Academy of Sciences and Art Serbia, Belgrade,18-20.September 2023. (2023):53-53,
https://hdl.handle.net/21.15107/rcub_dais_15224 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Smith, Steven
AU  - Mirković, M.
AU  - Peleš Tadić, Adriana
AU  - Tadić, Nenad
AU  - Đorđević, Antonije
PY  - 2022
UR  - https://dais.sanu.ac.rs/123456789/13622
AB  - Perovskite ceramic material based on MgTiO3 is used in various types of electronic devices owing to its dielectric properties, high dielectric constant, and low losses. These features can be tailored by setting preparation conditions. Densification of magnesium titanate by Spark Plasma Sintering (SPS) was the aim of this work. First, the mechanical activation in the highenergy ball mill was applied on the powder of MgO-TiO2 mixed in mole ratio 1:1. Prepared powder mixtures, activated for different times, were SPS sintered, at 1200 oC with a heating rate of 100oC/min. After reaching the desired temperature, a uniaxial pressure of 50 MPa was applied, and dwelled at this condition for 5 min, followed by cooling to room temperature at 5oC/min. The starting powders, activated mixtures, and sintered ceramics bodies were investigated by X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was noticed for the nonmilled ceramics. In the samples obtained from milled powders, MgTi2O5 was detected in EDS spectra in a lower amount, below the threshold of the XRD method. Dielectric measurements were performed at a wide range of frequencies and temperatures. The highest value of the hardness was obtained from powder milled for 15 min before SPS.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.
T1  - Effect of high energy ball milling on sintering of MgO-TiO2 system
SP  - 88
EP  - 88
UR  - https://hdl.handle.net/21.15107/rcub_dais_13622
ER  - 

@conference{
author = "Filipović, Suzana and Obradović, Nina and Fahrenholtz, William G. and Smith, Steven and Mirković, M. and Peleš Tadić, Adriana and Tadić, Nenad and Đorđević, Antonije",
year = "2022",
abstract = "Perovskite ceramic material based on MgTiO3 is used in various types of electronic devices owing to its dielectric properties, high dielectric constant, and low losses. These features can be tailored by setting preparation conditions. Densification of magnesium titanate by Spark Plasma Sintering (SPS) was the aim of this work. First, the mechanical activation in the highenergy ball mill was applied on the powder of MgO-TiO2 mixed in mole ratio 1:1. Prepared powder mixtures, activated for different times, were SPS sintered, at 1200 oC with a heating rate of 100oC/min. After reaching the desired temperature, a uniaxial pressure of 50 MPa was applied, and dwelled at this condition for 5 min, followed by cooling to room temperature at 5oC/min. The starting powders, activated mixtures, and sintered ceramics bodies were investigated by X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The presence of the MgTi2O5 phase was noticed for the nonmilled ceramics. In the samples obtained from milled powders, MgTi2O5 was detected in EDS spectra in a lower amount, below the threshold of the XRD method. Dielectric measurements were performed at a wide range of frequencies and temperatures. The highest value of the hardness was obtained from powder milled for 15 min before SPS.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.",
title = "Effect of high energy ball milling on sintering of MgO-TiO2 system",
pages = "88-88",
url = "https://hdl.handle.net/21.15107/rcub_dais_13622"
}

Filipović, S., Obradović, N., Fahrenholtz, W. G., Smith, S., Mirković, M., Peleš Tadić, A., Tadić, N.,& Đorđević, A.. (2022). Effect of high energy ball milling on sintering of MgO-TiO2 system. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.
Belgrade : Serbian Ceramic Society., 88-88.
https://hdl.handle.net/21.15107/rcub_dais_13622

Filipović S, Obradović N, Fahrenholtz WG, Smith S, Mirković M, Peleš Tadić A, Tadić N, Đorđević A. Effect of high energy ball milling on sintering of MgO-TiO2 system. in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022.. 2022;:88-88.
https://hdl.handle.net/21.15107/rcub_dais_13622 .

Filipović, Suzana, Obradović, Nina, Fahrenholtz, William G., Smith, Steven, Mirković, M., Peleš Tadić, Adriana, Tadić, Nenad, Đorđević, Antonije, "Effect of high energy ball milling on sintering of MgO-TiO2 system" in Program and the Book of abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application X New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 26-27. September 2022. (2022):88-88,
https://hdl.handle.net/21.15107/rcub_dais_13622 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Smith, Steven
AU  - Mirković, Miljana M.
AU  - Peleš, Adriana
AU  - Đorđević, Antonije
PY  - 2022
UR  - https://dais.sanu.ac.rs/123456789/13118
AB  - MgTiO3 is a material often used in different types of high-frequency capacitors, temperature compensating capacitors, and chip capacitors, so the enhancement of this material is still the focus of many research groups due to its remarkable dielectric properties. Outstanding features can only be achieved when the ceramics are highly dense. Densification of magnesium titanate by Spark Plasma Sintering (SPS) was the aim of this work. Magnesium titanate ceramics were prepared by applying mechanical activation as the first step. Powders prepared in this way were SPS sintered, at 1200 °C with a heating rate of 100 °C/min. After reaching the desired temperature, a uniaxial pressure of 50 MPa was applied. The dwell time at this condition was 5 min, followed by cooling to room temperature at 5°C/min. X-ray diffraction was performed in order to establish the phase composition of milled powders and obtained ceramics. Differences between samples milled in various times intervals, as well as sintered ceramics were examined by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The presence of MgTiz0s phase was detected in XRD and was confirmed by EDS analysis for the non-milled ceramics. In the samples obtained from milled powders, no MgTi2O5 was detected in XRD patterns, but this phase was detected in EDS spectra in a lower amount. Dielectric measurements were performed at a wide range of frequencies, while the hardness of the SPS samples was measured at loads up to 10 N. The highest value of the hardness was obtained from powder milled for 15 min before SPS.
PB  - Belgrade : Innovation Center of Faculty of Mechanical Engineering
C3  - Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2022, 05-08 July 2022, Zlatibor, Serbia
T1  - Spark plasma sintering of mechanically activated MGO-TiO2 system
SP  - 81
EP  - 81
UR  - https://hdl.handle.net/21.15107/rcub_dais_13118
ER  - 

@conference{
author = "Filipović, Suzana and Obradović, Nina and Fahrenholtz, William G. and Smith, Steven and Mirković, Miljana M. and Peleš, Adriana and Đorđević, Antonije",
year = "2022",
abstract = "MgTiO3 is a material often used in different types of high-frequency capacitors, temperature compensating capacitors, and chip capacitors, so the enhancement of this material is still the focus of many research groups due to its remarkable dielectric properties. Outstanding features can only be achieved when the ceramics are highly dense. Densification of magnesium titanate by Spark Plasma Sintering (SPS) was the aim of this work. Magnesium titanate ceramics were prepared by applying mechanical activation as the first step. Powders prepared in this way were SPS sintered, at 1200 °C with a heating rate of 100 °C/min. After reaching the desired temperature, a uniaxial pressure of 50 MPa was applied. The dwell time at this condition was 5 min, followed by cooling to room temperature at 5°C/min. X-ray diffraction was performed in order to establish the phase composition of milled powders and obtained ceramics. Differences between samples milled in various times intervals, as well as sintered ceramics were examined by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The presence of MgTiz0s phase was detected in XRD and was confirmed by EDS analysis for the non-milled ceramics. In the samples obtained from milled powders, no MgTi2O5 was detected in XRD patterns, but this phase was detected in EDS spectra in a lower amount. Dielectric measurements were performed at a wide range of frequencies, while the hardness of the SPS samples was measured at loads up to 10 N. The highest value of the hardness was obtained from powder milled for 15 min before SPS.",
publisher = "Belgrade : Innovation Center of Faculty of Mechanical Engineering",
journal = "Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2022, 05-08 July 2022, Zlatibor, Serbia",
title = "Spark plasma sintering of mechanically activated MGO-TiO2 system",
pages = "81-81",
url = "https://hdl.handle.net/21.15107/rcub_dais_13118"
}

Filipović, S., Obradović, N., Fahrenholtz, W. G., Smith, S., Mirković, M. M., Peleš, A.,& Đorđević, A.. (2022). Spark plasma sintering of mechanically activated MGO-TiO2 system. in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2022, 05-08 July 2022, Zlatibor, Serbia
Belgrade : Innovation Center of Faculty of Mechanical Engineering., 81-81.
https://hdl.handle.net/21.15107/rcub_dais_13118

Filipović S, Obradović N, Fahrenholtz WG, Smith S, Mirković MM, Peleš A, Đorđević A. Spark plasma sintering of mechanically activated MGO-TiO2 system. in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2022, 05-08 July 2022, Zlatibor, Serbia. 2022;:81-81.
https://hdl.handle.net/21.15107/rcub_dais_13118 .

Filipović, Suzana, Obradović, Nina, Fahrenholtz, William G., Smith, Steven, Mirković, Miljana M., Peleš, Adriana, Đorđević, Antonije, "Spark plasma sintering of mechanically activated MGO-TiO2 system" in Programme and The Book of Abstracts / International Conference of Experimental and Numerical Investigations and New Technologies - CNN TECH 2022, 05-08 July 2022, Zlatibor, Serbia (2022):81-81,
https://hdl.handle.net/21.15107/rcub_dais_13118 .