TY  - JOUR
AU  - Obradović, Nina
AU  - Filipović, Suzana
AU  - Fahrenholtz, William G.
AU  - Marinkovic, Bojan A.
AU  - Rogan, Jelena
AU  - Lević, Steva
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir B.
UR  - https://doiserbia.nb.rs/Article.aspx?ID=0350-820X2301001O
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/6372
AB  - Magnesium aluminate has the spinel structure along with good mechanical, chemical, and thermal properties. Magnesium aluminate has a wide range of applications including refractory ceramics, optically transparent ceramic windows, and armors. Its low dielectric permeability and low loss tangent enable its applications for integrated electronic devices, as well. In this paper, MgO and Al2O3 powders were mixed in a one-to-one molar ratio and calcined at temperatures ranging from 1500 to 1800o C to produce phase pure spinel. Thereafter, pellets were crushed and treated in a planetary ball mill for 60 min to obtain a fine powder. All powders were examined for phase composition, crystal structure, and morphology. The obtained results showed that by increasing the temperature, samples with higher density were synthesized. Milling for 1 h led to formation of larger particles, but finer powders after milling. XRPD and Raman spectroscopy showed disorder in the crystal structure after milling.
T2  - Science of Sintering, 55 (2023) 1-10
T1  - Morphological and structural characterization of MgAl2O4 spinel.
DO  - 10.2298/SOS2301001O
ER  - 

@article{
author = "Obradović, Nina and Filipović, Suzana and Fahrenholtz, William G. and Marinkovic, Bojan A. and Rogan, Jelena and Lević, Steva and Đorđević, Antonije and Pavlović, Vladimir B.",
abstract = "Magnesium aluminate has the spinel structure along with good mechanical, chemical, and thermal properties. Magnesium aluminate has a wide range of applications including refractory ceramics, optically transparent ceramic windows, and armors. Its low dielectric permeability and low loss tangent enable its applications for integrated electronic devices, as well. In this paper, MgO and Al2O3 powders were mixed in a one-to-one molar ratio and calcined at temperatures ranging from 1500 to 1800o C to produce phase pure spinel. Thereafter, pellets were crushed and treated in a planetary ball mill for 60 min to obtain a fine powder. All powders were examined for phase composition, crystal structure, and morphology. The obtained results showed that by increasing the temperature, samples with higher density were synthesized. Milling for 1 h led to formation of larger particles, but finer powders after milling. XRPD and Raman spectroscopy showed disorder in the crystal structure after milling.",
journal = "Science of Sintering, 55 (2023) 1-10",
title = "Morphological and structural characterization of MgAl2O4 spinel.",
doi = "10.2298/SOS2301001O"
}

Obradović, N., Filipović, S., Fahrenholtz, W. G., Marinkovic, B. A., Rogan, J., Lević, S., Đorđević, A.,& Pavlović, V. B..Morphological and structural characterization of MgAl2O4 spinel.. in Science of Sintering, 55 (2023) 1-10.
https://doi.org/10.2298/SOS2301001O

Obradović N, Filipović S, Fahrenholtz WG, Marinkovic BA, Rogan J, Lević S, Đorđević A, Pavlović VB. Morphological and structural characterization of MgAl2O4 spinel.. in Science of Sintering, 55 (2023) 1-10..
doi:10.2298/SOS2301001O .

Obradović, Nina, Filipović, Suzana, Fahrenholtz, William G., Marinkovic, Bojan A., Rogan, Jelena, Lević, Steva, Đorđević, Antonije, Pavlović, Vladimir B., "Morphological and structural characterization of MgAl2O4 spinel." in Science of Sintering, 55 (2023) 1-10,
https://doi.org/10.2298/SOS2301001O . .

TY  - JOUR
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Mitrić, Miodrag
AU  - Balać, Igor
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir
PY  - 2019
UR  - http://www.sciencedirect.com/science/article/pii/S0921883119302596
UR  - http://dais.sanu.ac.rs/123456789/7027
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5755
AB  - Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 °C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method overcomes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for ε'r and 0.003 for tanδ. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength.
PB  - Elsevier
T2  - Advanced Powder Technology
T1  - The effect of ball milling on properties of sintered manganese-doped alumina
EP  - 2540
IS  - 11
SP  - 2533
VL  - 30
DO  - 10.1016/j.apt.2019.07.033
ER  - 

@article{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Mitrić, Miodrag and Balać, Igor and Đorđević, Antonije and Pavlović, Vladimir",
year = "2019",
abstract = "Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 °C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method overcomes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for ε'r and 0.003 for tanδ. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength.",
publisher = "Elsevier",
journal = "Advanced Powder Technology",
title = "The effect of ball milling on properties of sintered manganese-doped alumina",
pages = "2540-2533",
number = "11",
volume = "30",
doi = "10.1016/j.apt.2019.07.033"
}

Filipović, S., Obradović, N., Marković, S., Mitrić, M., Balać, I., Đorđević, A.,& Pavlović, V.. (2019). The effect of ball milling on properties of sintered manganese-doped alumina. in Advanced Powder Technology
Elsevier., 30(11), 2533-2540.
https://doi.org/10.1016/j.apt.2019.07.033

Filipović S, Obradović N, Marković S, Mitrić M, Balać I, Đorđević A, Pavlović V. The effect of ball milling on properties of sintered manganese-doped alumina. in Advanced Powder Technology. 2019;30(11):2533-2540.
doi:10.1016/j.apt.2019.07.033 .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Mitrić, Miodrag, Balać, Igor, Đorđević, Antonije, Pavlović, Vladimir, "The effect of ball milling on properties of sintered manganese-doped alumina" in Advanced Powder Technology, 30, no. 11 (2019):2533-2540,
https://doi.org/10.1016/j.apt.2019.07.033 . .

TY  - JOUR
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Filipović, Suzana
AU  - Kosanović, Darko
AU  - Dapčević, A.
AU  - Đorđević, Antonije
AU  - Balać, Igor
AU  - Pavlović, Vladimir
PY  - 2019
UR  - http://www.sciencedirect.com/science/article/pii/S0272884219306340
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5761
AB  - Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and α-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 °C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.
PB  - Elsevier
T2  - Ceramics International
T1  - The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics
EP  - 12021
IS  - 9
SP  - 12015
VL  - 45
DO  - 10.1016/j.ceramint.2019.03.095
ER  - 

@article{
author = "Obradović, Nina and Fahrenholtz, William G. and Filipović, Suzana and Kosanović, Darko and Dapčević, A. and Đorđević, Antonije and Balać, Igor and Pavlović, Vladimir",
year = "2019",
abstract = "Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and α-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 °C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.",
publisher = "Elsevier",
journal = "Ceramics International",
title = "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics",
pages = "12021-12015",
number = "9",
volume = "45",
doi = "10.1016/j.ceramint.2019.03.095"
}

Obradović, N., Fahrenholtz, W. G., Filipović, S., Kosanović, D., Dapčević, A., Đorđević, A., Balać, I.,& Pavlović, V.. (2019). The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International
Elsevier., 45(9), 12015-12021.
https://doi.org/10.1016/j.ceramint.2019.03.095

Obradović N, Fahrenholtz WG, Filipović S, Kosanović D, Dapčević A, Đorđević A, Balać I, Pavlović V. The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International. 2019;45(9):12015-12021.
doi:10.1016/j.ceramint.2019.03.095 .

Obradović, Nina, Fahrenholtz, William G., Filipović, Suzana, Kosanović, Darko, Dapčević, A., Đorđević, Antonije, Balać, Igor, Pavlović, Vladimir, "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics" in Ceramics International, 45, no. 9 (2019):12015-12021,
https://doi.org/10.1016/j.ceramint.2019.03.095 . .

TY  - CONF
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Filipović, Suzana
AU  - Marković, Smilja
AU  - Blagojević, Vladimir A.
AU  - Lević, Steva
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir
PY  - 2019
UR  - http://dais.sanu.ac.rs/123456789/7020
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5752
AB  - Magnesium aluminate and other alumina-based spinels are refractory ceramics with excellent properties, such as high hardness, high mechanical strength, and low dielectric constant, applicable in many modern industries. MgAl2O4 was produced by solid state reaction between MgO and alpha-Al2O3 powders. Mechanical activation represents a very efficient method for increasing the reactivity of powders, accelerating chemical reactions and decreasing the sintering temperatures. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 60 minutes. Sintering was performed in air at temperatures ranging from 1200°C to 1600 °C with a 2 h dwell time. Initial powders and sintered samples were characterized using X-ray diffraction and scanning electron microscopy. Differential thermal analysis (DTA) and thermal gravimetry (TG) were used to determine the temperatures for synthesis reactions and phase transformations. Based on the DTA results, several different processes occured during heating, including evaporation of physisorbed water, decomposition of Mg(OH)2, and spinel formation. With mechanical activation, all characteristic temperatures shifted to lower values, and peaks were more pronounced. Raman spectra were used to characterize the degree of inversion as a function of sintering temperature for all of the sintered specimens.
PB  - Central and Eastern European Committee for Thermal Analysis and Calorimetry
C3  - Book of abstracts of the 5th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC5) and 14th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2019)
T1  - Influence of mechanical activation on kinetics and formation of spinel monitored by DTA
EP  - 70
SP  - 70
UR  - https://hdl.handle.net/21.15107/rcub_dais_7020
ER  - 

@conference{
author = "Obradović, Nina and Fahrenholtz, William G. and Filipović, Suzana and Marković, Smilja and Blagojević, Vladimir A. and Lević, Steva and Đorđević, Antonije and Pavlović, Vladimir",
year = "2019",
abstract = "Magnesium aluminate and other alumina-based spinels are refractory ceramics with excellent properties, such as high hardness, high mechanical strength, and low dielectric constant, applicable in many modern industries. MgAl2O4 was produced by solid state reaction between MgO and alpha-Al2O3 powders. Mechanical activation represents a very efficient method for increasing the reactivity of powders, accelerating chemical reactions and decreasing the sintering temperatures. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 60 minutes. Sintering was performed in air at temperatures ranging from 1200°C to 1600 °C with a 2 h dwell time. Initial powders and sintered samples were characterized using X-ray diffraction and scanning electron microscopy. Differential thermal analysis (DTA) and thermal gravimetry (TG) were used to determine the temperatures for synthesis reactions and phase transformations. Based on the DTA results, several different processes occured during heating, including evaporation of physisorbed water, decomposition of Mg(OH)2, and spinel formation. With mechanical activation, all characteristic temperatures shifted to lower values, and peaks were more pronounced. Raman spectra were used to characterize the degree of inversion as a function of sintering temperature for all of the sintered specimens.",
publisher = "Central and Eastern European Committee for Thermal Analysis and Calorimetry",
journal = "Book of abstracts of the 5th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC5) and 14th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2019)",
title = "Influence of mechanical activation on kinetics and formation of spinel monitored by DTA",
pages = "70-70",
url = "https://hdl.handle.net/21.15107/rcub_dais_7020"
}

Obradović, N., Fahrenholtz, W. G., Filipović, S., Marković, S., Blagojević, V. A., Lević, S., Đorđević, A.,& Pavlović, V.. (2019). Influence of mechanical activation on kinetics and formation of spinel monitored by DTA. in Book of abstracts of the 5th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC5) and 14th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2019)
Central and Eastern European Committee for Thermal Analysis and Calorimetry., 70-70.
https://hdl.handle.net/21.15107/rcub_dais_7020

Obradović N, Fahrenholtz WG, Filipović S, Marković S, Blagojević VA, Lević S, Đorđević A, Pavlović V. Influence of mechanical activation on kinetics and formation of spinel monitored by DTA. in Book of abstracts of the 5th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC5) and 14th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2019). 2019;:70-70.
https://hdl.handle.net/21.15107/rcub_dais_7020 .

Obradović, Nina, Fahrenholtz, William G., Filipović, Suzana, Marković, Smilja, Blagojević, Vladimir A., Lević, Steva, Đorđević, Antonije, Pavlović, Vladimir, "Influence of mechanical activation on kinetics and formation of spinel monitored by DTA" in Book of abstracts of the 5th Central and Eastern European Conference on Thermal Analysis and Calorimetry (CEEC-TAC5) and 14th Mediterranean Conference on Calorimetry and Thermal Analysis (Medicta2019) (2019):70-70,
https://hdl.handle.net/21.15107/rcub_dais_7020 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Balać, Igor
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir
PY  - 2019
UR  - http://dais.sanu.ac.rs/123456789/7025
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5754
AB  - Corundum (alpha-alumina) is one of the most exploited materials in ceramic industry due to its good physico-chemical properties, mechanical properties, and, importantly, due to its low cost. Advantageous properties, such as hardness, dielectric and thermal properties, and refractoriness, open the door to a wide range of applications of corundum. Porous alumina ceramics is often used for filters and as a catalytic substrate, whereas dense alumina ceramics is frequently used in automotive and aerospace industry. Hence, there is a great interest in exploring this type of ceramics. The aim of this work is to explain the influence of preparation parameters (mechanical activation, addition of transition metal oxides, and sintering conditions) on the final electrical and mechanical properties of alumina. 
As a starting powder, a mix of a few alumina modifications (α-, κ-,γ - Al2O3) was used. It was doped with 1 wt % of Mn2O3, Cr2O3, and NiO, respectively. Three of the obtained mixtures were homogenized and three were ball milled for 60 min. Particle size analysis, SEM, and EDS were performed in order to demonstrate changes in the microstructure after milling. DTA/TG analyses were used to determine all characteristic temperatures. After sintering at 1400 oC in an air atmosphere, mechanical, electrical, and physico-chemical properties of the obtained ceramics were determined. 
Results showed that the mechanical treatment lead to a decrease in temperatures of phase transitions and sintering for approximately 100 oC. Incorporation of cations of transition metals into the crystal lattice of alumina was noticed. Activated and sintered samples showed a higher tensile strength and higher relative dielectric permittivity then the sample doped with Cr2O3. 
The main conclusion of this investigation is that the mechanical activation has the dominant influence on lowering the characteristic temperatures of all detected phase transitions and sintering processes. Using a mixture of several crystalline phases of alumina as a starting powder alleviates the incorporation of transition-metal cations into the alumina crystal lattice, leading to changes in microstructures of the prepared ceramics. Finally, changes in the microstructure and lattice disordering have the dominant influence on the final mechanical properties.
PB  - Societa ceramica italiana
PB  - Politecnico di Torino
C3  - Abstract Book / XVI Conference and Exhibition of the European Ceramic Society XVI ECerS Conference, Torino, 16-20 June 2019
T1  - Electrical and mechanical properties of alumina doped with transition metal oxides sintered at 1400°C
EP  - 682
SP  - 682
UR  - https://hdl.handle.net/21.15107/rcub_dais_7025
ER  - 

@conference{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Balać, Igor and Đorđević, Antonije and Pavlović, Vladimir",
year = "2019",
abstract = "Corundum (alpha-alumina) is one of the most exploited materials in ceramic industry due to its good physico-chemical properties, mechanical properties, and, importantly, due to its low cost. Advantageous properties, such as hardness, dielectric and thermal properties, and refractoriness, open the door to a wide range of applications of corundum. Porous alumina ceramics is often used for filters and as a catalytic substrate, whereas dense alumina ceramics is frequently used in automotive and aerospace industry. Hence, there is a great interest in exploring this type of ceramics. The aim of this work is to explain the influence of preparation parameters (mechanical activation, addition of transition metal oxides, and sintering conditions) on the final electrical and mechanical properties of alumina. 
As a starting powder, a mix of a few alumina modifications (α-, κ-,γ - Al2O3) was used. It was doped with 1 wt % of Mn2O3, Cr2O3, and NiO, respectively. Three of the obtained mixtures were homogenized and three were ball milled for 60 min. Particle size analysis, SEM, and EDS were performed in order to demonstrate changes in the microstructure after milling. DTA/TG analyses were used to determine all characteristic temperatures. After sintering at 1400 oC in an air atmosphere, mechanical, electrical, and physico-chemical properties of the obtained ceramics were determined. 
Results showed that the mechanical treatment lead to a decrease in temperatures of phase transitions and sintering for approximately 100 oC. Incorporation of cations of transition metals into the crystal lattice of alumina was noticed. Activated and sintered samples showed a higher tensile strength and higher relative dielectric permittivity then the sample doped with Cr2O3. 
The main conclusion of this investigation is that the mechanical activation has the dominant influence on lowering the characteristic temperatures of all detected phase transitions and sintering processes. Using a mixture of several crystalline phases of alumina as a starting powder alleviates the incorporation of transition-metal cations into the alumina crystal lattice, leading to changes in microstructures of the prepared ceramics. Finally, changes in the microstructure and lattice disordering have the dominant influence on the final mechanical properties.",
publisher = "Societa ceramica italiana, Politecnico di Torino",
journal = "Abstract Book / XVI Conference and Exhibition of the European Ceramic Society XVI ECerS Conference, Torino, 16-20 June 2019",
title = "Electrical and mechanical properties of alumina doped with transition metal oxides sintered at 1400°C",
pages = "682-682",
url = "https://hdl.handle.net/21.15107/rcub_dais_7025"
}

Filipović, S., Obradović, N., Marković, S., Balać, I., Đorđević, A.,& Pavlović, V.. (2019). Electrical and mechanical properties of alumina doped with transition metal oxides sintered at 1400°C. in Abstract Book / XVI Conference and Exhibition of the European Ceramic Society XVI ECerS Conference, Torino, 16-20 June 2019
Societa ceramica italiana., 682-682.
https://hdl.handle.net/21.15107/rcub_dais_7025

Filipović S, Obradović N, Marković S, Balać I, Đorđević A, Pavlović V. Electrical and mechanical properties of alumina doped with transition metal oxides sintered at 1400°C. in Abstract Book / XVI Conference and Exhibition of the European Ceramic Society XVI ECerS Conference, Torino, 16-20 June 2019. 2019;:682-682.
https://hdl.handle.net/21.15107/rcub_dais_7025 .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Balać, Igor, Đorđević, Antonije, Pavlović, Vladimir, "Electrical and mechanical properties of alumina doped with transition metal oxides sintered at 1400°C" in Abstract Book / XVI Conference and Exhibition of the European Ceramic Society XVI ECerS Conference, Torino, 16-20 June 2019 (2019):682-682,
https://hdl.handle.net/21.15107/rcub_dais_7025 .

TY  - JOUR
AU  - Obradović, Nina
AU  - Fahrenholtz, William G.
AU  - Filipović, Suzana
AU  - Kosanović, Darko
AU  - Dapčević, A.
AU  - Đorđević, Antonije
AU  - Balać, Igor
AU  - Pavlović, Vladimir B.
PY  - 2019
UR  - http://www.sciencedirect.com/science/article/pii/S0272884219306340
UR  - http://dais.sanu.ac.rs/123456789/5272
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5740
AB  - Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and α-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 °C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.
PB  - Elsevier
T2  - Ceramics International
T1  - The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics
EP  - 12021
IS  - 9
SP  - 12015
VL  - 45
DO  - 10.1016/j.ceramint.2019.03.095
ER  - 

@article{
author = "Obradović, Nina and Fahrenholtz, William G. and Filipović, Suzana and Kosanović, Darko and Dapčević, A. and Đorđević, Antonije and Balać, Igor and Pavlović, Vladimir B.",
year = "2019",
abstract = "Magnesium aluminate, MgAl2O4 and other alumina-based spinels are ceramics with high hardness, high melting point and mechanical strenght. Spinels can also be used as dielectrics in microwave applications. The goal of this study was to examine the effects of mechanical activation and sintering temperatures on physico-chemical properties of spinel. MgAl2O4 was produced by solid state reaction between MgO and α-Al2O3. The starting powders were mixed by ball milling to homogenize without significant particle size reduction. Mechanical activation of mixed powders was performed in a high-energy planetary ball mill in air for 1 h. Powders were compacted at 300 MPa. Heat treatments were performed in air, at temperatures ranging from 1200 to 1600 °C with 2 h dwell time, to determine the amount of spinel formation as a function of temperature. Phase composition and microstructure of initial powders and heated samples were determined by means of X-ray diffraction, particle size analysis, and scanning electron microscopy. The influences of milling and consolidation parameters were studied by electrical measurements and mechanical characterization. The main conclusion of this study was that mechanical activation for 60 min initiated a mechano-chemical reaction, resulted in spinel formation at much lower temperatures than within non-activated powders, and indicated that final sintering stage started at much lower temperatures for activated powders. Changes in microstructure parameters, as a consequence of mechanical treatment and subsequent heating of investigated powder mixtures, strongly affect electrical and mechanical properties of the final ceramics.",
publisher = "Elsevier",
journal = "Ceramics International",
title = "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics",
pages = "12021-12015",
number = "9",
volume = "45",
doi = "10.1016/j.ceramint.2019.03.095"
}

Obradović, N., Fahrenholtz, W. G., Filipović, S., Kosanović, D., Dapčević, A., Đorđević, A., Balać, I.,& Pavlović, V. B.. (2019). The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International
Elsevier., 45(9), 12015-12021.
https://doi.org/10.1016/j.ceramint.2019.03.095

Obradović N, Fahrenholtz WG, Filipović S, Kosanović D, Dapčević A, Đorđević A, Balać I, Pavlović VB. The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics. in Ceramics International. 2019;45(9):12015-12021.
doi:10.1016/j.ceramint.2019.03.095 .

Obradović, Nina, Fahrenholtz, William G., Filipović, Suzana, Kosanović, Darko, Dapčević, A., Đorđević, Antonije, Balać, Igor, Pavlović, Vladimir B., "The effect of mechanical activation on synthesis and properties of MgAl2O4 ceramics" in Ceramics International, 45, no. 9 (2019):12015-12021,
https://doi.org/10.1016/j.ceramint.2019.03.095 . .

TY  - JOUR
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Mitrić, Miodrag
AU  - Balać, Igor
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir
PY  - 2019
UR  - http://www.sciencedirect.com/science/article/pii/S0921883119302596
UR  - http://dais.sanu.ac.rs/123456789/6951
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5745
AB  - Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 °C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method overcomes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for ε'r and 0.003 for tanδ. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength.
PB  - Elsevier
T2  - Advanced Powder Technology
T1  - The effect of ball milling on properties of sintered manganese-doped alumina
EP  - 2540
IS  - 11
SP  - 2533
VL  - 30
DO  - 10.1016/j.apt.2019.07.033
ER  - 

@article{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Mitrić, Miodrag and Balać, Igor and Đorđević, Antonije and Pavlović, Vladimir",
year = "2019",
abstract = "Alumina-based compounds have many technological applications and attract great attention even after decades of investigation, due to their good chemical, electrical, and mechanical properties. A mixture of several alumina modifications (α-, κ-, γ-Al2O3) doped with 1 wt% of Mn2O3 was used for this experiment. The powder was mechanically activated for 60 min in an ethanol medium. After compaction, green bodies were sintered in the temperature range from 1200 to 1400 °C. Microstructures of the obtained specimens were investigated by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS). The influence of morphological changes on electrical and mechanical properties was examined in detail. We have developed a test fixture and corresponding software for measurement of the relative dielectric permittivity and the loss tangent of ceramic specimens. This new method overcomes the problems of dimensions and shape of samples, as well as the problem of applying silver paste. The accuracy is around 2% for ε'r and 0.003 for tanδ. We demonstrate that the mechanical activation (MA) has the dominant influence on lowering the characteristic temperatures and microstructure development, which further leads to increased permittivity and tensile strength.",
publisher = "Elsevier",
journal = "Advanced Powder Technology",
title = "The effect of ball milling on properties of sintered manganese-doped alumina",
pages = "2540-2533",
number = "11",
volume = "30",
doi = "10.1016/j.apt.2019.07.033"
}

Filipović, S., Obradović, N., Marković, S., Mitrić, M., Balać, I., Đorđević, A.,& Pavlović, V.. (2019). The effect of ball milling on properties of sintered manganese-doped alumina. in Advanced Powder Technology
Elsevier., 30(11), 2533-2540.
https://doi.org/10.1016/j.apt.2019.07.033

Filipović S, Obradović N, Marković S, Mitrić M, Balać I, Đorđević A, Pavlović V. The effect of ball milling on properties of sintered manganese-doped alumina. in Advanced Powder Technology. 2019;30(11):2533-2540.
doi:10.1016/j.apt.2019.07.033 .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Mitrić, Miodrag, Balać, Igor, Đorđević, Antonije, Pavlović, Vladimir, "The effect of ball milling on properties of sintered manganese-doped alumina" in Advanced Powder Technology, 30, no. 11 (2019):2533-2540,
https://doi.org/10.1016/j.apt.2019.07.033 . .

TY  - CONF
AU  - Obradović, Nina
AU  - Gigov, Mihajlo
AU  - Đorđević, Aleksandar
AU  - Kern, Frank
AU  - Dmitrović, Svetlana
AU  - Matović, Branko
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir B.
PY  - 2018
UR  - http://dais.sanu.ac.rs/123456789/3667
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5726
AB  - The paper presents results of investigation of the influence of mechanical activation of shungite, a Russian natural mineral rich in silica and carbon, on its sintering behavior. The mechanical activation of the starting powder was performed in a high-energy ball mill in time intervals from 0 to 480 minutes. The phase composition of the starting mixtures and sintered samples was analyzed by the X-ray diffraction method. The scanning electron microscopy was performed in order to determine changes in the microstructure. Sintering was performed at various temperatures for 2 h, in an Ar and vacuum atmosphere. Dielectric properties of the sintered samples were measured in the frequency range from 1 to 500 MHz. The obtained results indicate that sintered shungite powder is a good candidate for applications as an absorber of electromagnetic waves in microwave engineering.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
T1  - Shungite - a Russian mineral: possible application as a microwave absorber
EP  - 94
SP  - 94
UR  - https://hdl.handle.net/21.15107/rcub_dais_3667
ER  - 

@conference{
author = "Obradović, Nina and Gigov, Mihajlo and Đorđević, Aleksandar and Kern, Frank and Dmitrović, Svetlana and Matović, Branko and Đorđević, Antonije and Pavlović, Vladimir B.",
year = "2018",
abstract = "The paper presents results of investigation of the influence of mechanical activation of shungite, a Russian natural mineral rich in silica and carbon, on its sintering behavior. The mechanical activation of the starting powder was performed in a high-energy ball mill in time intervals from 0 to 480 minutes. The phase composition of the starting mixtures and sintered samples was analyzed by the X-ray diffraction method. The scanning electron microscopy was performed in order to determine changes in the microstructure. Sintering was performed at various temperatures for 2 h, in an Ar and vacuum atmosphere. Dielectric properties of the sintered samples were measured in the frequency range from 1 to 500 MHz. The obtained results indicate that sintered shungite powder is a good candidate for applications as an absorber of electromagnetic waves in microwave engineering.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018",
title = "Shungite - a Russian mineral: possible application as a microwave absorber",
pages = "94-94",
url = "https://hdl.handle.net/21.15107/rcub_dais_3667"
}

Obradović, N., Gigov, M., Đorđević, A., Kern, F., Dmitrović, S., Matović, B., Đorđević, A.,& Pavlović, V. B.. (2018). Shungite - a Russian mineral: possible application as a microwave absorber. in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
Belgrade : Materials Research Society of Serbia., 94-94.
https://hdl.handle.net/21.15107/rcub_dais_3667

Obradović N, Gigov M, Đorđević A, Kern F, Dmitrović S, Matović B, Đorđević A, Pavlović VB. Shungite - a Russian mineral: possible application as a microwave absorber. in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018. 2018;:94-94.
https://hdl.handle.net/21.15107/rcub_dais_3667 .

Obradović, Nina, Gigov, Mihajlo, Đorđević, Aleksandar, Kern, Frank, Dmitrović, Svetlana, Matović, Branko, Đorđević, Antonije, Pavlović, Vladimir B., "Shungite - a Russian mineral: possible application as a microwave absorber" in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018 (2018):94-94,
https://hdl.handle.net/21.15107/rcub_dais_3667 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Đorđević, Antonije
AU  - Dapčević, Aleksandra
AU  - Rogan, Jelena
AU  - Pavlović, Vladimir B.
PY  - 2018
UR  - http://dais.sanu.ac.rs/123456789/3634
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5725
AB  - Sintered alumina powder represents suitable material for usage in various industry fields (e.g., as chip carriers in electronics, microwaves, jewelry production), due to convenient physical properties, such as sinterability, electrical and mechanical features. Those properties can be modified by addition of different oxides and/or mechanical treatment. Therefore, in this investigation the alumina was doped with 1 wt. % of Cr2O3, Mn2O3 and NiO, respectively, followed by 1 hour of mechanical activation at 400 rpm in planetary ball mill. Sintering of powder mixtures was tracked by sensitive dilatometer up to 1400 °C. The final density values varied from cca. 2 ̶ 3.2 g/cm3. Changes in microstructure were observed by means of SEM. The influence of additives along with mechanical activation is monitored trough changes in electrical permittivity and loss tangent. Compared to pure alumina, the additives lower the relative permittivity and increase dielectric losses. For a given mixture, the sintering increases the relative permittivity and decreases losses.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
T1  - Sintering of alumina doped with different oxides, followed by sensitive dilatometer
EP  - 95
SP  - 95
UR  - https://hdl.handle.net/21.15107/rcub_dais_3634
ER  - 

@conference{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Đorđević, Antonije and Dapčević, Aleksandra and Rogan, Jelena and Pavlović, Vladimir B.",
year = "2018",
abstract = "Sintered alumina powder represents suitable material for usage in various industry fields (e.g., as chip carriers in electronics, microwaves, jewelry production), due to convenient physical properties, such as sinterability, electrical and mechanical features. Those properties can be modified by addition of different oxides and/or mechanical treatment. Therefore, in this investigation the alumina was doped with 1 wt. % of Cr2O3, Mn2O3 and NiO, respectively, followed by 1 hour of mechanical activation at 400 rpm in planetary ball mill. Sintering of powder mixtures was tracked by sensitive dilatometer up to 1400 °C. The final density values varied from cca. 2 ̶ 3.2 g/cm3. Changes in microstructure were observed by means of SEM. The influence of additives along with mechanical activation is monitored trough changes in electrical permittivity and loss tangent. Compared to pure alumina, the additives lower the relative permittivity and increase dielectric losses. For a given mixture, the sintering increases the relative permittivity and decreases losses.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018",
title = "Sintering of alumina doped with different oxides, followed by sensitive dilatometer",
pages = "95-95",
url = "https://hdl.handle.net/21.15107/rcub_dais_3634"
}

Filipović, S., Obradović, N., Marković, S., Đorđević, A., Dapčević, A., Rogan, J.,& Pavlović, V. B.. (2018). Sintering of alumina doped with different oxides, followed by sensitive dilatometer. in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018
Belgrade : Materials Research Society of Serbia., 95-95.
https://hdl.handle.net/21.15107/rcub_dais_3634

Filipović S, Obradović N, Marković S, Đorđević A, Dapčević A, Rogan J, Pavlović VB. Sintering of alumina doped with different oxides, followed by sensitive dilatometer. in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018. 2018;:95-95.
https://hdl.handle.net/21.15107/rcub_dais_3634 .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Đorđević, Antonije, Dapčević, Aleksandra, Rogan, Jelena, Pavlović, Vladimir B., "Sintering of alumina doped with different oxides, followed by sensitive dilatometer" in Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018 (2018):95-95,
https://hdl.handle.net/21.15107/rcub_dais_3634 .

TY  - CONF
AU  - Filipović, Suzana
AU  - Obradović, Nina
AU  - Marković, Smilja
AU  - Mitrić, Miodrag
AU  - Đorđević, Antonije
AU  - Dapčević, Aleksandra
AU  - Rogan, Jelena
AU  - Pavlović, Vladimir B.
PY  - 2018
UR  - http://dais.sanu.ac.rs/123456789/4114
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5731
AB  - Recently, with the huge use of smart gadgets, developing of smart jewelry represents a very interesting segment in material science, as well as in electronic science. Alumina is widely used ceramic in many industrial fields as pigments, catalysis, microelectronics, etc., mostly because of its low cost and appropriate mechanical and electrical properties, high surface area and thermal stability. Also, modified alumina could be applied in production of smart jewelry. Thus, the main objectives of this investigation is to improve features of sintered alumina doped with Mn2O3 along with mechanical treatment, in order to obtain strong ceramic with low values of dielectric loss and low relative dielectric permittivity, as well as esthetic. Commercial alumina powder was doped with 1 wt % of manganese oxide and treated in planetary ball mill for an hour. Characteristic temperatures of both powders (non-activated and activated one) were investigated in detail by DTA and TG analyses. After sintering at 1200, 1300, and 1400 oC for 2 h, XRD patterns and SEM images were recorded. Furthermore, mechanical and electrical properties were examined for all sintered samples.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VII : New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 17-19 September 2018
T1  - Effects of ball-milling on properties of sintered alumina doped with Mn2O3
EP  - 75
SP  - 75
UR  - https://hdl.handle.net/21.15107/rcub_dais_4114
ER  - 

@conference{
author = "Filipović, Suzana and Obradović, Nina and Marković, Smilja and Mitrić, Miodrag and Đorđević, Antonije and Dapčević, Aleksandra and Rogan, Jelena and Pavlović, Vladimir B.",
year = "2018",
abstract = "Recently, with the huge use of smart gadgets, developing of smart jewelry represents a very interesting segment in material science, as well as in electronic science. Alumina is widely used ceramic in many industrial fields as pigments, catalysis, microelectronics, etc., mostly because of its low cost and appropriate mechanical and electrical properties, high surface area and thermal stability. Also, modified alumina could be applied in production of smart jewelry. Thus, the main objectives of this investigation is to improve features of sintered alumina doped with Mn2O3 along with mechanical treatment, in order to obtain strong ceramic with low values of dielectric loss and low relative dielectric permittivity, as well as esthetic. Commercial alumina powder was doped with 1 wt % of manganese oxide and treated in planetary ball mill for an hour. Characteristic temperatures of both powders (non-activated and activated one) were investigated in detail by DTA and TG analyses. After sintering at 1200, 1300, and 1400 oC for 2 h, XRD patterns and SEM images were recorded. Furthermore, mechanical and electrical properties were examined for all sintered samples.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VII : New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 17-19 September 2018",
title = "Effects of ball-milling on properties of sintered alumina doped with Mn2O3",
pages = "75-75",
url = "https://hdl.handle.net/21.15107/rcub_dais_4114"
}

Filipović, S., Obradović, N., Marković, S., Mitrić, M., Đorđević, A., Dapčević, A., Rogan, J.,& Pavlović, V. B.. (2018). Effects of ball-milling on properties of sintered alumina doped with Mn2O3. in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VII : New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 17-19 September 2018
Belgrade : Serbian Ceramic Society., 75-75.
https://hdl.handle.net/21.15107/rcub_dais_4114

Filipović S, Obradović N, Marković S, Mitrić M, Đorđević A, Dapčević A, Rogan J, Pavlović VB. Effects of ball-milling on properties of sintered alumina doped with Mn2O3. in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VII : New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 17-19 September 2018. 2018;:75-75.
https://hdl.handle.net/21.15107/rcub_dais_4114 .

Filipović, Suzana, Obradović, Nina, Marković, Smilja, Mitrić, Miodrag, Đorđević, Antonije, Dapčević, Aleksandra, Rogan, Jelena, Pavlović, Vladimir B., "Effects of ball-milling on properties of sintered alumina doped with Mn2O3" in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VII : New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, 17-19 September 2018 (2018):75-75,
https://hdl.handle.net/21.15107/rcub_dais_4114 .

TY  - CONF
AU  - Obradović, Nina
AU  - Đorđević, Nataša
AU  - Kosanović, Darko
AU  - Filipović, Suzana
AU  - Kachlik, Martin
AU  - Maca, Karel
AU  - Olćan, Dragan
AU  - Đorđević, Antonije
AU  - Pavlović, Vladimir B.
PY  - 2017
UR  - http://dais.sanu.ac.rs/123456789/15444
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5720
AB  - In this study, sintering of two systems was investigated in parallel, pure cordierite 2MgO:2Al2O3:5SiO2, and cordierite with addition of 5 mass % TeO2. Green bodies were prepared from powder mixtures mechanically activated for 0, 10 and 40minutes by uniaxial pressing at 20 MPa followed by cold isostatic pressing (CIP) at 1000 MPa. The pressure-less sintering of these specimens was performed at a temperature of 1350 oC for 1 h, with 10 oC/min heating rate. Densities over 96 % of theoretical values were obtained for samples activated for 40 minutes. XRD measurements of MAS-40 sintered sample pointed at a mixture that consisted of several phases, majority of cordierite (> 73 %), spinel MgAl2O4 (> 22 %), ZrSiO4 (2.5 %), and Al2O3 (1.8%), while XRD pattern of MAS-40-TeO2 contained majority of cordierite (> 72 %), spinel MgAl2O4 (> 23 %), ZrSiO4 (1.9 %), and Al2O3 (1.9 %). The relative permittivities of the samples were measured in an open test fixture. The results for the real part of the complex relative permittivity of the samples, measured at 200 MHz, are shown in Table I. The loss tangent for all samples was very small, below the resolution of the measurement setup (0.005).
There is a strong correlation between the relative permittivity and the density, which agrees with our previous results.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Nineteenth Annual Conference YUCOMAT 2017, Herceg Novi, September 4-8, 2017
T1  - Characterization of pressure-less sintered MgO-Al2O3-SiO2-TeO2 system
EP  - 70
SP  - 70
UR  - https://hdl.handle.net/21.15107/rcub_dais_15444
ER  - 

@conference{
author = "Obradović, Nina and Đorđević, Nataša and Kosanović, Darko and Filipović, Suzana and Kachlik, Martin and Maca, Karel and Olćan, Dragan and Đorđević, Antonije and Pavlović, Vladimir B.",
year = "2017",
abstract = "In this study, sintering of two systems was investigated in parallel, pure cordierite 2MgO:2Al2O3:5SiO2, and cordierite with addition of 5 mass % TeO2. Green bodies were prepared from powder mixtures mechanically activated for 0, 10 and 40minutes by uniaxial pressing at 20 MPa followed by cold isostatic pressing (CIP) at 1000 MPa. The pressure-less sintering of these specimens was performed at a temperature of 1350 oC for 1 h, with 10 oC/min heating rate. Densities over 96 % of theoretical values were obtained for samples activated for 40 minutes. XRD measurements of MAS-40 sintered sample pointed at a mixture that consisted of several phases, majority of cordierite (> 73 %), spinel MgAl2O4 (> 22 %), ZrSiO4 (2.5 %), and Al2O3 (1.8%), while XRD pattern of MAS-40-TeO2 contained majority of cordierite (> 72 %), spinel MgAl2O4 (> 23 %), ZrSiO4 (1.9 %), and Al2O3 (1.9 %). The relative permittivities of the samples were measured in an open test fixture. The results for the real part of the complex relative permittivity of the samples, measured at 200 MHz, are shown in Table I. The loss tangent for all samples was very small, below the resolution of the measurement setup (0.005).
There is a strong correlation between the relative permittivity and the density, which agrees with our previous results.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Nineteenth Annual Conference YUCOMAT 2017, Herceg Novi, September 4-8, 2017",
title = "Characterization of pressure-less sintered MgO-Al2O3-SiO2-TeO2 system",
pages = "70-70",
url = "https://hdl.handle.net/21.15107/rcub_dais_15444"
}

Obradović, N., Đorđević, N., Kosanović, D., Filipović, S., Kachlik, M., Maca, K., Olćan, D., Đorđević, A.,& Pavlović, V. B.. (2017). Characterization of pressure-less sintered MgO-Al2O3-SiO2-TeO2 system. in Programme and The Book of Abstracts / Nineteenth Annual Conference YUCOMAT 2017, Herceg Novi, September 4-8, 2017
Belgrade : Materials Research Society of Serbia., 70-70.
https://hdl.handle.net/21.15107/rcub_dais_15444

Obradović N, Đorđević N, Kosanović D, Filipović S, Kachlik M, Maca K, Olćan D, Đorđević A, Pavlović VB. Characterization of pressure-less sintered MgO-Al2O3-SiO2-TeO2 system. in Programme and The Book of Abstracts / Nineteenth Annual Conference YUCOMAT 2017, Herceg Novi, September 4-8, 2017. 2017;:70-70.
https://hdl.handle.net/21.15107/rcub_dais_15444 .

Obradović, Nina, Đorđević, Nataša, Kosanović, Darko, Filipović, Suzana, Kachlik, Martin, Maca, Karel, Olćan, Dragan, Đorđević, Antonije, Pavlović, Vladimir B., "Characterization of pressure-less sintered MgO-Al2O3-SiO2-TeO2 system" in Programme and The Book of Abstracts / Nineteenth Annual Conference YUCOMAT 2017, Herceg Novi, September 4-8, 2017 (2017):70-70,
https://hdl.handle.net/21.15107/rcub_dais_15444 .

TY  - CONF
AU  - Olćan, Dragan
AU  - Obradović, Nina
AU  - Filipović, Suzana
AU  - Terzić, Anja
AU  - Pavlović, Vladimir B.
AU  - Kachlik, Martin
AU  - Maca, Karel
AU  - Đorđević, Antonije
PY  - 2017
UR  - http://dais.sanu.ac.rs/123456789/4824
UR  - http://aspace.agrif.bg.ac.rs/handle/123456789/5738
AB  - We present an overview of electromagnetic numerical techniques and measurement apparatus that have been used for assessing electrical properties of ceramic samples. The complex permittivity of the ceramics is typically the first electromagnetic property of interest. In the measurement approach that we use, ceramic samples, in the shape of pills with metalized faces, are placed in either a proprietary coaxial chamber or in an open fixture. The scattering parameter (reflection coefficient) is measured using a network analyzer. For the deembedding of the complex permittivity of a sample one needs precise electromagnetic simulations, including detailed models of the chamber or the open fixture. For lower and intermediate frequencies we use a numerical technique for electrostatic analysis, based on the method of moments with Galerkin testing. We create a database that is used afterwards for evaluation of the complex permittivity practically in real time. For higher frequencies, a full electrodynamic model of the chamber is developed with WIPL-D software. For all our deembedding techniques, we have also developed a detailed model of losses in the SMA coaxial connectors, which is essential for a precise evaluation of the imaginary part of the complex permittivity for low-loss dielectrics. We present results of several measurements in order to illustrate the used techniques.
PB  - Belgrade : Serbian Ceramic Society
C3  - Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VI: New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, September 18-20, 2017
T1  - Assessing electrical properties of ceramic samples
EP  - 52
SP  - 51
UR  - https://hdl.handle.net/21.15107/rcub_dais_4824
ER  - 

@conference{
author = "Olćan, Dragan and Obradović, Nina and Filipović, Suzana and Terzić, Anja and Pavlović, Vladimir B. and Kachlik, Martin and Maca, Karel and Đorđević, Antonije",
year = "2017",
abstract = "We present an overview of electromagnetic numerical techniques and measurement apparatus that have been used for assessing electrical properties of ceramic samples. The complex permittivity of the ceramics is typically the first electromagnetic property of interest. In the measurement approach that we use, ceramic samples, in the shape of pills with metalized faces, are placed in either a proprietary coaxial chamber or in an open fixture. The scattering parameter (reflection coefficient) is measured using a network analyzer. For the deembedding of the complex permittivity of a sample one needs precise electromagnetic simulations, including detailed models of the chamber or the open fixture. For lower and intermediate frequencies we use a numerical technique for electrostatic analysis, based on the method of moments with Galerkin testing. We create a database that is used afterwards for evaluation of the complex permittivity practically in real time. For higher frequencies, a full electrodynamic model of the chamber is developed with WIPL-D software. For all our deembedding techniques, we have also developed a detailed model of losses in the SMA coaxial connectors, which is essential for a precise evaluation of the imaginary part of the complex permittivity for low-loss dielectrics. We present results of several measurements in order to illustrate the used techniques.",
publisher = "Belgrade : Serbian Ceramic Society",
journal = "Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VI: New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, September 18-20, 2017",
title = "Assessing electrical properties of ceramic samples",
pages = "52-51",
url = "https://hdl.handle.net/21.15107/rcub_dais_4824"
}

Olćan, D., Obradović, N., Filipović, S., Terzić, A., Pavlović, V. B., Kachlik, M., Maca, K.,& Đorđević, A.. (2017). Assessing electrical properties of ceramic samples. in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VI: New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, September 18-20, 2017
Belgrade : Serbian Ceramic Society., 51-52.
https://hdl.handle.net/21.15107/rcub_dais_4824

Olćan D, Obradović N, Filipović S, Terzić A, Pavlović VB, Kachlik M, Maca K, Đorđević A. Assessing electrical properties of ceramic samples. in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VI: New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, September 18-20, 2017. 2017;:51-52.
https://hdl.handle.net/21.15107/rcub_dais_4824 .

Olćan, Dragan, Obradović, Nina, Filipović, Suzana, Terzić, Anja, Pavlović, Vladimir B., Kachlik, Martin, Maca, Karel, Đorđević, Antonije, "Assessing electrical properties of ceramic samples" in Program and the Book of Abstracts / Serbian Ceramic Society Conference Advanced Ceramics and Application VI: New Frontiers in Multifunctional Material Science and Processing, Serbia, Belgrade, September 18-20, 2017 (2017):51-52,
https://hdl.handle.net/21.15107/rcub_dais_4824 .