TY  - CONF
AU  - Radojković, Aleksandar
AU  - Žunić, Milan
AU  - Savić, Slavica
AU  - Perać, Sanja
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2343
AB  - BaCe0.9Y0.1O3–δ has been known as one of the best proton conducting electrolyte, which enables its application in intermediate-temperature solid oxide fuel cells (IT-SOFC) operating between 500 °C and 700 °C. The main disadvantage of this material is its instability in a CO2-rich atmosphere that limits its application with respect to fuel selection. Therefore, many attempts has been made to improve its stability by replacing yttrium with other dopants, or by co-doping.
In this study, we compared BaCe0.9Y0.1O3–δ and BaCe0.85Y0.1M0.05O3–δ (M = {In, Zr, Nb}) electrolytes by taking into consideration the dopant properties (primarily the valence, electronegativity and ionic radius) and how they influenced the microstructure, conductivity and chemical stability of doped BaCeO3. The samples were synthesized by the citric-nitric autocombustion method. BaCe0.85Y0.1In0.05O3–δ was sintered at 1400 °C for 5 h in air, while the temperature of 1550 °C was required for the other materials to complete the sintering. This makes the doping with In a preferable method since sintering temperatures above 1500 °C can lead to a certain materials degradation resulting in BaO loss. The total conductivities (σ) measured at 700 °C in wet hydrogen decreased in the following order:
BaCe0.9Y0.1O3–δ > BaCe0.85Y0.1Zr0.05O3–δ > BaCe0.85Y0.1Nb0.05O3–δ > BaCe0.85Y0.1In0.05O3–δ. By comparing the stability of the ceramics exposed to a 100% CO2 atmosphere at 700 °C for 5 h and examined by X-ray analysis, it was observed that only BaCe0.85Y0.1In0.05O3–δ could sustain the aggressive environment. The exposed sample contained only traces of secondary phases, while the other compositions were partially or significantly decomposed. By taking into account the values of the Goldschmidt tolerance factor (t) and dopant electronegativity
PB  - Spectus Meeting World
C3  - 7th World Congress on Materials Science & Engineering
T1  - Tailoring of BaCe0.9Y0.1O3-d Electrolyte Properties by Co-Doping
IS  - 49
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2343
ER  - 

@conference{
author = "Radojković, Aleksandar and Žunić, Milan and Savić, Slavica and Perać, Sanja and Branković, Zorica and Branković, Goran",
year = "2023",
abstract = "BaCe0.9Y0.1O3–δ has been known as one of the best proton conducting electrolyte, which enables its application in intermediate-temperature solid oxide fuel cells (IT-SOFC) operating between 500 °C and 700 °C. The main disadvantage of this material is its instability in a CO2-rich atmosphere that limits its application with respect to fuel selection. Therefore, many attempts has been made to improve its stability by replacing yttrium with other dopants, or by co-doping.
In this study, we compared BaCe0.9Y0.1O3–δ and BaCe0.85Y0.1M0.05O3–δ (M = {In, Zr, Nb}) electrolytes by taking into consideration the dopant properties (primarily the valence, electronegativity and ionic radius) and how they influenced the microstructure, conductivity and chemical stability of doped BaCeO3. The samples were synthesized by the citric-nitric autocombustion method. BaCe0.85Y0.1In0.05O3–δ was sintered at 1400 °C for 5 h in air, while the temperature of 1550 °C was required for the other materials to complete the sintering. This makes the doping with In a preferable method since sintering temperatures above 1500 °C can lead to a certain materials degradation resulting in BaO loss. The total conductivities (σ) measured at 700 °C in wet hydrogen decreased in the following order:
BaCe0.9Y0.1O3–δ > BaCe0.85Y0.1Zr0.05O3–δ > BaCe0.85Y0.1Nb0.05O3–δ > BaCe0.85Y0.1In0.05O3–δ. By comparing the stability of the ceramics exposed to a 100% CO2 atmosphere at 700 °C for 5 h and examined by X-ray analysis, it was observed that only BaCe0.85Y0.1In0.05O3–δ could sustain the aggressive environment. The exposed sample contained only traces of secondary phases, while the other compositions were partially or significantly decomposed. By taking into account the values of the Goldschmidt tolerance factor (t) and dopant electronegativity",
publisher = "Spectus Meeting World",
journal = "7th World Congress on Materials Science & Engineering",
title = "Tailoring of BaCe0.9Y0.1O3-d Electrolyte Properties by Co-Doping",
number = "49",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2343"
}

Radojković, A., Žunić, M., Savić, S., Perać, S., Branković, Z.,& Branković, G.. (2023). Tailoring of BaCe0.9Y0.1O3-d Electrolyte Properties by Co-Doping. in 7th World Congress on Materials Science & Engineering
Spectus Meeting World.(49).
https://hdl.handle.net/21.15107/rcub_rimsi_2343

Radojković A, Žunić M, Savić S, Perać S, Branković Z, Branković G. Tailoring of BaCe0.9Y0.1O3-d Electrolyte Properties by Co-Doping. in 7th World Congress on Materials Science & Engineering. 2023;(49).
https://hdl.handle.net/21.15107/rcub_rimsi_2343 .

Radojković, Aleksandar, Žunić, Milan, Savić, Slavica, Perać, Sanja, Branković, Zorica, Branković, Goran, "Tailoring of BaCe0.9Y0.1O3-d Electrolyte Properties by Co-Doping" in 7th World Congress on Materials Science & Engineering, no. 49 (2023),
https://hdl.handle.net/21.15107/rcub_rimsi_2343 .

TY  - GEN
AU  - Mitrović, Jelena
AU  - Počuča-Nešić, Milica
AU  - Malešević, Aleksandar
AU  - Branković, Zorica
AU  - Vojisavljević, Katarina
AU  - Savić, Slavica
AU  - Ribić, Vesna
AU  - Drev, Sandra
AU  - Podlogar, Matejka
AU  - Bernik, Slavko
AU  - Rapljenović, Željko
AU  - Ivek, Tomislav
AU  - Branković, Goran
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2085
AB  - The non-magnetic, non-inductive electroconductive materials with linear current-voltage characteristic and low and almost constant electrical resistivity in the wide temperature range could be used in conditions unfavorable for metals and alloys. Particular emphasis is placed on the performance and endurance of these materials in conditions at constant high voltage, current, and energy, as well as operating in acidic and humid environmental conditions.
The aim of this work was to investigate the influence of antimony concentration and sintering parameters on the structure, microstructure, and electrical properties of antimony-doped barium stannate, BaSn1-xSbxO3 (BSSO, x = 0,00; 0,04; 0,06; 0,08 and 0,10) to obtain conductive electroceramic samples with linear current-voltage (I- U) characteristics and low electrical resistivity. For this purpose three different sintering techniques were used: conventional, spark plasma and cold sintering.
According to the X-ray diffraction (XRD) analysis, single-phase ceramic mater- ials with cubic BaSnO3 structure were obtained by conventional sintering at 1600 °C for 3 h and spark plasma sintering at 1100 °C for 5 min. Raising the spark plasma sintering temperature to 1200 °C induced the formation of Ba-rich secondary phase, Ba2SnO4. XRD analysis confirmed the presence of unreacted SnO2 and BaCO3 in cold sintered BaSn0.92Sb0.08O3 sample (310 °C for 5 min, 20 wt.% 1 M acetic acid). Scanning electron microscopy (SEM) indicates a significant decrease in grain size upon doping, regardless of the sintering technique. High-resolution transmission electron microscopy (HRTEM) revealed the presence of low angle grain boundaries (LAGBs) in conventionally and spark plasma sintered (1200 °C for 5 min) samples with x = 0.08. The results of electrical measurements confirmed the semiconducting properties of all BSSO, except the spark plasma sintered BaSn0.92Sb0.08O3 (1200 °C for 5 min) sample. This sample showed linear current-voltage characteristic, the lowest and almost constant electrical resistivity in the temperature range of 25–150
°C resulting from the loss of potential barriers at grain boundaries due to the large fraction of LAGBs present in BaSn0.92Sb0.08O3 ceramic sample.
PB  - University of Belgrade, Institute for Multidisciplinary Research
T2  - 7th Conference of the Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbia
T1  - Correlation between the microstructure and electrical properties of Sb-doped BaSnO3 ceramics
SP  - 36
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2085
ER  - 

@misc{
author = "Mitrović, Jelena and Počuča-Nešić, Milica and Malešević, Aleksandar and Branković, Zorica and Vojisavljević, Katarina and Savić, Slavica and Ribić, Vesna and Drev, Sandra and Podlogar, Matejka and Bernik, Slavko and Rapljenović, Željko and Ivek, Tomislav and Branković, Goran",
year = "2023",
abstract = "The non-magnetic, non-inductive electroconductive materials with linear current-voltage characteristic and low and almost constant electrical resistivity in the wide temperature range could be used in conditions unfavorable for metals and alloys. Particular emphasis is placed on the performance and endurance of these materials in conditions at constant high voltage, current, and energy, as well as operating in acidic and humid environmental conditions.
The aim of this work was to investigate the influence of antimony concentration and sintering parameters on the structure, microstructure, and electrical properties of antimony-doped barium stannate, BaSn1-xSbxO3 (BSSO, x = 0,00; 0,04; 0,06; 0,08 and 0,10) to obtain conductive electroceramic samples with linear current-voltage (I- U) characteristics and low electrical resistivity. For this purpose three different sintering techniques were used: conventional, spark plasma and cold sintering.
According to the X-ray diffraction (XRD) analysis, single-phase ceramic mater- ials with cubic BaSnO3 structure were obtained by conventional sintering at 1600 °C for 3 h and spark plasma sintering at 1100 °C for 5 min. Raising the spark plasma sintering temperature to 1200 °C induced the formation of Ba-rich secondary phase, Ba2SnO4. XRD analysis confirmed the presence of unreacted SnO2 and BaCO3 in cold sintered BaSn0.92Sb0.08O3 sample (310 °C for 5 min, 20 wt.% 1 M acetic acid). Scanning electron microscopy (SEM) indicates a significant decrease in grain size upon doping, regardless of the sintering technique. High-resolution transmission electron microscopy (HRTEM) revealed the presence of low angle grain boundaries (LAGBs) in conventionally and spark plasma sintered (1200 °C for 5 min) samples with x = 0.08. The results of electrical measurements confirmed the semiconducting properties of all BSSO, except the spark plasma sintered BaSn0.92Sb0.08O3 (1200 °C for 5 min) sample. This sample showed linear current-voltage characteristic, the lowest and almost constant electrical resistivity in the temperature range of 25–150
°C resulting from the loss of potential barriers at grain boundaries due to the large fraction of LAGBs present in BaSn0.92Sb0.08O3 ceramic sample.",
publisher = "University of Belgrade, Institute for Multidisciplinary Research",
journal = "7th Conference of the Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbia",
title = "Correlation between the microstructure and electrical properties of Sb-doped BaSnO3 ceramics",
pages = "36",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2085"
}

Mitrović, J., Počuča-Nešić, M., Malešević, A., Branković, Z., Vojisavljević, K., Savić, S., Ribić, V., Drev, S., Podlogar, M., Bernik, S., Rapljenović, Ž., Ivek, T.,& Branković, G.. (2023). Correlation between the microstructure and electrical properties of Sb-doped BaSnO3 ceramics. in 7th Conference of the Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbia
University of Belgrade, Institute for Multidisciplinary Research., 36.
https://hdl.handle.net/21.15107/rcub_rimsi_2085

Mitrović J, Počuča-Nešić M, Malešević A, Branković Z, Vojisavljević K, Savić S, Ribić V, Drev S, Podlogar M, Bernik S, Rapljenović Ž, Ivek T, Branković G. Correlation between the microstructure and electrical properties of Sb-doped BaSnO3 ceramics. in 7th Conference of the Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbia. 2023;:36.
https://hdl.handle.net/21.15107/rcub_rimsi_2085 .

Mitrović, Jelena, Počuča-Nešić, Milica, Malešević, Aleksandar, Branković, Zorica, Vojisavljević, Katarina, Savić, Slavica, Ribić, Vesna, Drev, Sandra, Podlogar, Matejka, Bernik, Slavko, Rapljenović, Željko, Ivek, Tomislav, Branković, Goran, "Correlation between the microstructure and electrical properties of Sb-doped BaSnO3 ceramics" in 7th Conference of the Serbian Society for Ceramic Materials, 7CSCS-2023, June 14-16, 2023, Belgrade, Serbia (2023):36,
https://hdl.handle.net/21.15107/rcub_rimsi_2085 .

TY  - JOUR
AU  - Perać, Sanja
AU  - M.Savić, Slavica
AU  - Branković, Zorica
AU  - Bernik, Slavko
AU  - Radojković, Aleksandar
AU  - Kojić, Sanja
AU  - Vasiljević, Dragana
AU  - Branković, Goran
PY  - 2022
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1561
AB  - Polycrystalline samples of NaCo2−xCuxO4 (x = 0, 0.01, 0.03, 0.05) were obtained from powder precursors synthesized by a mechanochemically assisted solid-state reaction method (MASSR) and a citric acid complex method (CAC). Ceramic samples were prepared by pressing into disc-shaped pellets and subsequently sintering at 880 °C in an argon atmosphere. Effects of low concentrations of Cu doping and the above-mentioned synthesis procedures on the thermoelectric and mechanical properties were observed. The electrical resistivity (ρ), the thermal conductivity (κ) and the Seebeck coefficient (S) were measured simultaneously in the temperature gradient (ΔT) between the hot and cold side of the sample, and the figure of merit (ZT) was subsequently calculated. The ZT of the CAC samples was higher compared with the MASSR samples. The highest ZT value of 0.061 at ΔT = 473 K was obtained for the sample with 5 mol% of Cu prepared by the CAC method. The CAC samples showed better mechanical properties compared to the MASSR samples due to the higher hardness of the CAC samples which is a consequence of homogeneous microstructure and higher density obtained during sintering of these samples. The results confirmed that, besides the concentration of Cu, the synthesis procedure considerably affected the thermoelectric and mechanical properties of NaCo2O4 (NCO) ceramics.
PB  - MDPI
T2  - Materials
T1  - Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4
SP  - 4470
VL  - 15
DO  - 10.3390/ma15134470
ER  - 

@article{
author = "Perać, Sanja and M.Savić, Slavica and Branković, Zorica and Bernik, Slavko and Radojković, Aleksandar and Kojić, Sanja and Vasiljević, Dragana and Branković, Goran",
year = "2022",
abstract = "Polycrystalline samples of NaCo2−xCuxO4 (x = 0, 0.01, 0.03, 0.05) were obtained from powder precursors synthesized by a mechanochemically assisted solid-state reaction method (MASSR) and a citric acid complex method (CAC). Ceramic samples were prepared by pressing into disc-shaped pellets and subsequently sintering at 880 °C in an argon atmosphere. Effects of low concentrations of Cu doping and the above-mentioned synthesis procedures on the thermoelectric and mechanical properties were observed. The electrical resistivity (ρ), the thermal conductivity (κ) and the Seebeck coefficient (S) were measured simultaneously in the temperature gradient (ΔT) between the hot and cold side of the sample, and the figure of merit (ZT) was subsequently calculated. The ZT of the CAC samples was higher compared with the MASSR samples. The highest ZT value of 0.061 at ΔT = 473 K was obtained for the sample with 5 mol% of Cu prepared by the CAC method. The CAC samples showed better mechanical properties compared to the MASSR samples due to the higher hardness of the CAC samples which is a consequence of homogeneous microstructure and higher density obtained during sintering of these samples. The results confirmed that, besides the concentration of Cu, the synthesis procedure considerably affected the thermoelectric and mechanical properties of NaCo2O4 (NCO) ceramics.",
publisher = "MDPI",
journal = "Materials",
title = "Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4",
pages = "4470",
volume = "15",
doi = "10.3390/ma15134470"
}

Perać, S., M.Savić, S., Branković, Z., Bernik, S., Radojković, A., Kojić, S., Vasiljević, D.,& Branković, G.. (2022). Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4. in Materials
MDPI., 15, 4470.
https://doi.org/10.3390/ma15134470

Perać S, M.Savić S, Branković Z, Bernik S, Radojković A, Kojić S, Vasiljević D, Branković G. Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4. in Materials. 2022;15:4470.
doi:10.3390/ma15134470 .

Perać, Sanja, M.Savić, Slavica, Branković, Zorica, Bernik, Slavko, Radojković, Aleksandar, Kojić, Sanja, Vasiljević, Dragana, Branković, Goran, "Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4" in Materials, 15 (2022):4470,
https://doi.org/10.3390/ma15134470 . .

TY  - CONF
AU  - Radojković, Aleksandar
AU  - Žunić, Milan
AU  - Savić, Slavica
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2017
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2334
AB  - The proton conductivity is an exclusive property of mixed oxides with
perovskite structure and large unit cell volume, such as BaCeO3 or SrCeO3. Doping
with aliovalent cations (Y3+) that replace Ce4+ induces formation of point defects
(oxygen vacancies), which in wet or hydrogen containing atmosphere produce
proton defects highly mobile at elevated temperatures. BaCe0.9Y0.1O3-δ (BCY) is one
of the best proton conducting electrolyte at temperatures between 500 and 700 ºC,
which allows its application in intermediate-temperature solid oxide fuel cells (ITSOFC).
Yet, one of the main drawbacks of this material is its instability in CO2-rich
atmospheres. Since BCY is basic in character, it normally reacts with CO2 to form
BaCO3 and yttria doped ceria. Both products exhibit no proton conductivity, thus
limiting application of BCY in IT-SOFCs where CO2 appears as a product of
electrochemical performance. However, the stability of BCY can be improved by
doping with cations that may raise the acidic character of the material, such as Nb5+,
Ta5+ or In3+. Introduction of Nb5+ and Ta5+ will reduce the amount of point defects
and consequently decrease the proton conductivity. This relation has been known as
trade-off effect. Nevertheless, if their molar concentration exceed no more than 5%
it is possible to obtain functional electrolytes with satisfying stability and
conductivity. On the other hand, trivalent In3+ can completely replace Y3+ since it
can both serve as a point defect source and increase acidity of the crystal lattice.
Accordingly, it can be introduced in much larger amounts than Nb5+ or Ta5+.
In this study BaCe0.9-xNbxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) and
BaCe1-xInxO3-δ (where x = 0.15, 0.20 and 0.25) powders were synthesized by the
method of autocombustion, while BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and
0.05) powders were prepared by the classical solid state route. Much higher specific
surface areas were observed for the samples synthesized by the autocombustion
method. In the case of the samples doped with Nb and Ta, the dense electrolytes
were formed after sintering at 1550 ºC for 5 h in air. Temperature of 1300 °C was
enough to complete sintering of the samples doped with In after 5 h in air, which
was another advantage of In as a dopant. The conductivities determined by
impedance measurements in temperature range of 550–700 °C in wet hydrogen
showed a decreasing trend with increase of Nb and Ta content, while it was the
opposite in the case of In. Interestingly, the total conductivity of
BaCe0.85Nb0.05Y0.1O3-δ, BaCe0.85Ta0.05Y0.1O3-δ and BaCe0.75In0.25O3-δ reached around
5×10–3 S/cm in wet hydrogen atmosphere at 700 °C. After exposure in 100 % CO2
atmosphere at 700 °C for 5 h, the samples were investigated by X-ray analysis. It
was found that even 15 % In could completely supress degradation of the
electrolyte, while the highest concentrations of Nb and Ta (5%) were necessary to
secure sufficient stability in CO2.
PB  - Društvo za keramičke materijale Srbije
C3  - 4th Conference of The Serbian Society for Ceramic Materials
T1  - Improved properties of doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC
EP  - 51
SP  - 50
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2334
ER  - 

@conference{
author = "Radojković, Aleksandar and Žunić, Milan and Savić, Slavica and Branković, Zorica and Branković, Goran",
year = "2017",
abstract = "The proton conductivity is an exclusive property of mixed oxides with
perovskite structure and large unit cell volume, such as BaCeO3 or SrCeO3. Doping
with aliovalent cations (Y3+) that replace Ce4+ induces formation of point defects
(oxygen vacancies), which in wet or hydrogen containing atmosphere produce
proton defects highly mobile at elevated temperatures. BaCe0.9Y0.1O3-δ (BCY) is one
of the best proton conducting electrolyte at temperatures between 500 and 700 ºC,
which allows its application in intermediate-temperature solid oxide fuel cells (ITSOFC).
Yet, one of the main drawbacks of this material is its instability in CO2-rich
atmospheres. Since BCY is basic in character, it normally reacts with CO2 to form
BaCO3 and yttria doped ceria. Both products exhibit no proton conductivity, thus
limiting application of BCY in IT-SOFCs where CO2 appears as a product of
electrochemical performance. However, the stability of BCY can be improved by
doping with cations that may raise the acidic character of the material, such as Nb5+,
Ta5+ or In3+. Introduction of Nb5+ and Ta5+ will reduce the amount of point defects
and consequently decrease the proton conductivity. This relation has been known as
trade-off effect. Nevertheless, if their molar concentration exceed no more than 5%
it is possible to obtain functional electrolytes with satisfying stability and
conductivity. On the other hand, trivalent In3+ can completely replace Y3+ since it
can both serve as a point defect source and increase acidity of the crystal lattice.
Accordingly, it can be introduced in much larger amounts than Nb5+ or Ta5+.
In this study BaCe0.9-xNbxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) and
BaCe1-xInxO3-δ (where x = 0.15, 0.20 and 0.25) powders were synthesized by the
method of autocombustion, while BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and
0.05) powders were prepared by the classical solid state route. Much higher specific
surface areas were observed for the samples synthesized by the autocombustion
method. In the case of the samples doped with Nb and Ta, the dense electrolytes
were formed after sintering at 1550 ºC for 5 h in air. Temperature of 1300 °C was
enough to complete sintering of the samples doped with In after 5 h in air, which
was another advantage of In as a dopant. The conductivities determined by
impedance measurements in temperature range of 550–700 °C in wet hydrogen
showed a decreasing trend with increase of Nb and Ta content, while it was the
opposite in the case of In. Interestingly, the total conductivity of
BaCe0.85Nb0.05Y0.1O3-δ, BaCe0.85Ta0.05Y0.1O3-δ and BaCe0.75In0.25O3-δ reached around
5×10–3 S/cm in wet hydrogen atmosphere at 700 °C. After exposure in 100 % CO2
atmosphere at 700 °C for 5 h, the samples were investigated by X-ray analysis. It
was found that even 15 % In could completely supress degradation of the
electrolyte, while the highest concentrations of Nb and Ta (5%) were necessary to
secure sufficient stability in CO2.",
publisher = "Društvo za keramičke materijale Srbije",
journal = "4th Conference of The Serbian Society for Ceramic Materials",
title = "Improved properties of doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC",
pages = "51-50",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2334"
}

Radojković, A., Žunić, M., Savić, S., Branković, Z.,& Branković, G.. (2017). Improved properties of doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC. in 4th Conference of The Serbian Society for Ceramic Materials
Društvo za keramičke materijale Srbije., 50-51.
https://hdl.handle.net/21.15107/rcub_rimsi_2334

Radojković A, Žunić M, Savić S, Branković Z, Branković G. Improved properties of doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC. in 4th Conference of The Serbian Society for Ceramic Materials. 2017;:50-51.
https://hdl.handle.net/21.15107/rcub_rimsi_2334 .

Radojković, Aleksandar, Žunić, Milan, Savić, Slavica, Branković, Zorica, Branković, Goran, "Improved properties of doped BaCe0.9Y0.1O3-δ as a proton conducting electrolyte for IT-SOFC" in 4th Conference of The Serbian Society for Ceramic Materials (2017):50-51,
https://hdl.handle.net/21.15107/rcub_rimsi_2334 .

TY  - CONF
AU  - Radojković, Aleksandar
AU  - Žunić, M
AU  - Savić, Slavica
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2016
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2339
AB  - BaCe0.9Y0.1O3-δ (BCY) has been one of the most studied materials known for its highest proton conductivity at temperatures between 500 and 700 ºC, which allows its application as a proton conducting electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFC). The proton conductivity is an exclusive property of mixed oxides with perovskite structure and large unit cell volume, such as BaCeO3 or SrCeO3. Doping with aliovalent cations (Y3+) that replace Ce4+ induces formation of point defects (oxygen vacancies), which in wet or hydrogen containing atmosphere allow proton mobility. The main disadvantage of this material is its instability in CO2-rich atmosphere due to the basic character of the crystal lattice, thus limiting its application in SOFCs in respect to fuel selection. However, the stability of BCY can be enhanced by doping with cations that may raise the acidic character of the material, such as Nb5+, Ta5+ or In3+. Introduction of pentivalent cations will lead to reduced amount of point defects and consequently lower proton conductivity and it is therefore recommended that their molar concentration should not exceed 5 %. On the other hand, trivalent In3+ is more suitable as it can completely replace Y3+ since it can both serve as a point defect source and increase acidity of the crystal lattice. Because of these properties it can be introduced in much larger amounts than Nb5+ or Ta5+.
In this study BaCe0.9-xNbxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) and BaCe1-xInxO3-δ (where x = 0.15, 0.20 and 0.25) powders were synthesized by the method of autocombustion, while BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) powders were prepared by the classical solid state route. Much higher specific surface areas were observed for the samples synthesized by the autocombustion method. In the case of Nb and Ta doped samples, the dense electrolytes were formed after sintering at 1550 ºC for 5 h in air. Temperature of 1300 ºC was enough to complete sintering of the samples doped with In after 5 h in air, which was another advantage of In as a dopant. The conductivities determined by impedance measurements in temperature range of 550-700 ºC in wet hydrogen showed a decreasing trend with increase of Nb and Ta content, while it was the opposite in the case of In. Interestingly, the total conductivity of the samples BaCe0.85Nb0.05Y0.1O3-δ, BaCe0.85Ta0.05Y0.1O3-δ and BaCe0.75In0.25O3-δ reached around 5×10–3 S/cm in wet hydrogen atmosphere at 700 ºC. After exposure in 100 % CO2 atmosphere at 700 ºC for 5 h, the samples were investigated by X-ray analysis. It was found that even 15 % In could completely supress degradation of electrolyte, while the highest concentrations of Nb and Ta (5%) were necessary to secure sufficient stability in CO2.
PB  - Univerzitet u Beogradu, Fakultet za fizičku hemiju
C3  - 2nd International Meeting on Materials Science for Energy Related Applications
T1  - Chemical Stability of Doped BaCe0.9Y0.1O3-x as a Proton Conducting Electrolyte for IT-SOFC
EP  - 8
SP  - 7
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2339
ER  - 

@conference{
author = "Radojković, Aleksandar and Žunić, M and Savić, Slavica and Branković, Zorica and Branković, Goran",
year = "2016",
abstract = "BaCe0.9Y0.1O3-δ (BCY) has been one of the most studied materials known for its highest proton conductivity at temperatures between 500 and 700 ºC, which allows its application as a proton conducting electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFC). The proton conductivity is an exclusive property of mixed oxides with perovskite structure and large unit cell volume, such as BaCeO3 or SrCeO3. Doping with aliovalent cations (Y3+) that replace Ce4+ induces formation of point defects (oxygen vacancies), which in wet or hydrogen containing atmosphere allow proton mobility. The main disadvantage of this material is its instability in CO2-rich atmosphere due to the basic character of the crystal lattice, thus limiting its application in SOFCs in respect to fuel selection. However, the stability of BCY can be enhanced by doping with cations that may raise the acidic character of the material, such as Nb5+, Ta5+ or In3+. Introduction of pentivalent cations will lead to reduced amount of point defects and consequently lower proton conductivity and it is therefore recommended that their molar concentration should not exceed 5 %. On the other hand, trivalent In3+ is more suitable as it can completely replace Y3+ since it can both serve as a point defect source and increase acidity of the crystal lattice. Because of these properties it can be introduced in much larger amounts than Nb5+ or Ta5+.
In this study BaCe0.9-xNbxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) and BaCe1-xInxO3-δ (where x = 0.15, 0.20 and 0.25) powders were synthesized by the method of autocombustion, while BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and 0.05) powders were prepared by the classical solid state route. Much higher specific surface areas were observed for the samples synthesized by the autocombustion method. In the case of Nb and Ta doped samples, the dense electrolytes were formed after sintering at 1550 ºC for 5 h in air. Temperature of 1300 ºC was enough to complete sintering of the samples doped with In after 5 h in air, which was another advantage of In as a dopant. The conductivities determined by impedance measurements in temperature range of 550-700 ºC in wet hydrogen showed a decreasing trend with increase of Nb and Ta content, while it was the opposite in the case of In. Interestingly, the total conductivity of the samples BaCe0.85Nb0.05Y0.1O3-δ, BaCe0.85Ta0.05Y0.1O3-δ and BaCe0.75In0.25O3-δ reached around 5×10–3 S/cm in wet hydrogen atmosphere at 700 ºC. After exposure in 100 % CO2 atmosphere at 700 ºC for 5 h, the samples were investigated by X-ray analysis. It was found that even 15 % In could completely supress degradation of electrolyte, while the highest concentrations of Nb and Ta (5%) were necessary to secure sufficient stability in CO2.",
publisher = "Univerzitet u Beogradu, Fakultet za fizičku hemiju",
journal = "2nd International Meeting on Materials Science for Energy Related Applications",
title = "Chemical Stability of Doped BaCe0.9Y0.1O3-x as a Proton Conducting Electrolyte for IT-SOFC",
pages = "8-7",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2339"
}

Radojković, A., Žunić, M., Savić, S., Branković, Z.,& Branković, G.. (2016). Chemical Stability of Doped BaCe0.9Y0.1O3-x as a Proton Conducting Electrolyte for IT-SOFC. in 2nd International Meeting on Materials Science for Energy Related Applications
Univerzitet u Beogradu, Fakultet za fizičku hemiju., 7-8.
https://hdl.handle.net/21.15107/rcub_rimsi_2339

Radojković A, Žunić M, Savić S, Branković Z, Branković G. Chemical Stability of Doped BaCe0.9Y0.1O3-x as a Proton Conducting Electrolyte for IT-SOFC. in 2nd International Meeting on Materials Science for Energy Related Applications. 2016;:7-8.
https://hdl.handle.net/21.15107/rcub_rimsi_2339 .

Radojković, Aleksandar, Žunić, M, Savić, Slavica, Branković, Zorica, Branković, Goran, "Chemical Stability of Doped BaCe0.9Y0.1O3-x as a Proton Conducting Electrolyte for IT-SOFC" in 2nd International Meeting on Materials Science for Energy Related Applications (2016):7-8,
https://hdl.handle.net/21.15107/rcub_rimsi_2339 .

TY  - CONF
AU  - Radojković, Aleksandar
AU  - Savić, Slavica
AU  - Jović, Nataša
AU  - Ćirković, Jovana
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2015
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2338
AB  - BaCe0.9Eu0.1O2.95 (BCE) powder was synthesized by citric-nitric autocombustion
method. According to Rietveld analysis, BCE also possesses slightly larger unit cell
volume than mostly investigated BaCe0.9Y0.1O2.95 (BCY), which allows higher
proton mobility through the perovskite lattice. Sinterability of BaCeO3 is enhanced
by doping with Eu since dense electrolyte microstructure with 1–2 μm grains can be
obtained at temperatures below 1500 ºC. Conductivity measurements revealed
separate bulk and grain boundary contributions to the total electrolyte conductivity
below 200 ºC. The grain boundary conductivity was one order of magnitude higher
than the bulk conductivity, indicating the blocking effect of the grain boundaries to
the mobility of charge carriers. As this effect ceased with temperature, it was
possible to determine only total conductivities above 500 ºC. Conductivity of BCE
in a wet hydrogen atmosphere at 600 ºC reached 1.2 × 10–2
S/cm, which can be considered as one of the highest conductivities among BaCeO3 based proton
conductors. Thus, doping of BaCeO3 with europium offers multiple improvements
that can eventually lead to decrease in operating temperature of SOFCs based on this
type of proton conducting electrolyte
PB  - Društvo za keramičke materijale Srbije
C3  - 3rd Conference of the Serbian Society for Ceramic Materials
T1  - Eu doped barium cerium oxide as a promising electrolyte for intermediate temperature SOFCs
SP  - 53
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2338
ER  - 

@conference{
author = "Radojković, Aleksandar and Savić, Slavica and Jović, Nataša and Ćirković, Jovana and Branković, Zorica and Branković, Goran",
year = "2015",
abstract = "BaCe0.9Eu0.1O2.95 (BCE) powder was synthesized by citric-nitric autocombustion
method. According to Rietveld analysis, BCE also possesses slightly larger unit cell
volume than mostly investigated BaCe0.9Y0.1O2.95 (BCY), which allows higher
proton mobility through the perovskite lattice. Sinterability of BaCeO3 is enhanced
by doping with Eu since dense electrolyte microstructure with 1–2 μm grains can be
obtained at temperatures below 1500 ºC. Conductivity measurements revealed
separate bulk and grain boundary contributions to the total electrolyte conductivity
below 200 ºC. The grain boundary conductivity was one order of magnitude higher
than the bulk conductivity, indicating the blocking effect of the grain boundaries to
the mobility of charge carriers. As this effect ceased with temperature, it was
possible to determine only total conductivities above 500 ºC. Conductivity of BCE
in a wet hydrogen atmosphere at 600 ºC reached 1.2 × 10–2
S/cm, which can be considered as one of the highest conductivities among BaCeO3 based proton
conductors. Thus, doping of BaCeO3 with europium offers multiple improvements
that can eventually lead to decrease in operating temperature of SOFCs based on this
type of proton conducting electrolyte",
publisher = "Društvo za keramičke materijale Srbije",
journal = "3rd Conference of the Serbian Society for Ceramic Materials",
title = "Eu doped barium cerium oxide as a promising electrolyte for intermediate temperature SOFCs",
pages = "53",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2338"
}

Radojković, A., Savić, S., Jović, N., Ćirković, J., Branković, Z.,& Branković, G.. (2015). Eu doped barium cerium oxide as a promising electrolyte for intermediate temperature SOFCs. in 3rd Conference of the Serbian Society for Ceramic Materials
Društvo za keramičke materijale Srbije., 53.
https://hdl.handle.net/21.15107/rcub_rimsi_2338

Radojković A, Savić S, Jović N, Ćirković J, Branković Z, Branković G. Eu doped barium cerium oxide as a promising electrolyte for intermediate temperature SOFCs. in 3rd Conference of the Serbian Society for Ceramic Materials. 2015;:53.
https://hdl.handle.net/21.15107/rcub_rimsi_2338 .

Radojković, Aleksandar, Savić, Slavica, Jović, Nataša, Ćirković, Jovana, Branković, Zorica, Branković, Goran, "Eu doped barium cerium oxide as a promising electrolyte for intermediate temperature SOFCs" in 3rd Conference of the Serbian Society for Ceramic Materials (2015):53,
https://hdl.handle.net/21.15107/rcub_rimsi_2338 .

Radojković, A., Savić, S., Žunić, M., Branković, Z.,& Branković, G.. (2014). Laboratorijski prototip za ispitivanje električnih karakteristika materijala u različitim uslovima atmosfere i temperaturnog režima. in Univerzitet u Beogradu, Institut za multidisciplinarna istraživanja.
https://hdl.handle.net/21.15107/rcub_rimsi_2382

Radojković A, Savić S, Žunić M, Branković Z, Branković G. Laboratorijski prototip za ispitivanje električnih karakteristika materijala u različitim uslovima atmosfere i temperaturnog režima. in Univerzitet u Beogradu, Institut za multidisciplinarna istraživanja. 2014;.
https://hdl.handle.net/21.15107/rcub_rimsi_2382 .

Radojković, Aleksandar, Savić, Slavica, Žunić, Milan, Branković, Zorica, Branković, Goran, "Laboratorijski prototip za ispitivanje električnih karakteristika materijala u različitim uslovima atmosfere i temperaturnog režima" in Univerzitet u Beogradu, Institut za multidisciplinarna istraživanja (2014),
https://hdl.handle.net/21.15107/rcub_rimsi_2382 .

TY  - CONF
AU  - Radojković, Aleksandar
AU  - Savić, Slavica
AU  - Žunić, Milan
AU  - Branković, Zorica
AU  - Branković, Goran
PY  - 2013
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2337
AB  - BaCe0.9-xNbxY0.1O3-δ and BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and 0.05)
powders were synthesized by solid-state reaction method to investigate the influence
of dopant and concentration on chemical stability and electrical properties of the
sintered samples. The dense electrolyte pellets were formed from the powders after
being uniaxially pressed and sintered at 1550ºC for 5h. The electrical conductivities
determined by impedance measurements in temperature range of 550-750 ºC in wet
hydrogen atmosphere showed a decreasing trend with increase of Nb and Ta
content. On the other hand, stability of the sintered samples treated in 100% CO2 at
700 ºC for 5h determined by X-ray analysis was enhanced with increased
concentrations of Nb and Ta. It was found that BaCe0.87Nb0.3Y0.1O3-δ is the optimal
composition that satisfies the opposite demands for electrical conductivity and
chemical stability, reaching 8.0.
10-3
Sm.
cm
-1
in wet hydrogen at 650 ºC compared to
1.0.
10-2
Sm.
cm
-1
for undoped electrolyte. Similar results obtained by doping with Nb
and Ta can be explained by almost equal size and same valence of Nb and Ta
cations, as well as their similar electronegativities. The electrolyte characteristics are
strongly dependent on these properties, whereas doping with Nb showed slightly
higher conductivities for each dopant concentration.
PB  - Društvo za keramičke materijale Srbije
C3  - 2rd Conference of the Serbian Society for Ceramic Materials
T1  - Chemical stability enhancement of doped BaCe0.9Y0.1O3-δ as an electrolyte for proton conducting SOFCs
SP  - 90
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2337
ER  - 

@conference{
author = "Radojković, Aleksandar and Savić, Slavica and Žunić, Milan and Branković, Zorica and Branković, Goran",
year = "2013",
abstract = "BaCe0.9-xNbxY0.1O3-δ and BaCe0.9-xTaxY0.1O3-δ (where x = 0.01, 0.03 and 0.05)
powders were synthesized by solid-state reaction method to investigate the influence
of dopant and concentration on chemical stability and electrical properties of the
sintered samples. The dense electrolyte pellets were formed from the powders after
being uniaxially pressed and sintered at 1550ºC for 5h. The electrical conductivities
determined by impedance measurements in temperature range of 550-750 ºC in wet
hydrogen atmosphere showed a decreasing trend with increase of Nb and Ta
content. On the other hand, stability of the sintered samples treated in 100% CO2 at
700 ºC for 5h determined by X-ray analysis was enhanced with increased
concentrations of Nb and Ta. It was found that BaCe0.87Nb0.3Y0.1O3-δ is the optimal
composition that satisfies the opposite demands for electrical conductivity and
chemical stability, reaching 8.0.
10-3
Sm.
cm
-1
in wet hydrogen at 650 ºC compared to
1.0.
10-2
Sm.
cm
-1
for undoped electrolyte. Similar results obtained by doping with Nb
and Ta can be explained by almost equal size and same valence of Nb and Ta
cations, as well as their similar electronegativities. The electrolyte characteristics are
strongly dependent on these properties, whereas doping with Nb showed slightly
higher conductivities for each dopant concentration.",
publisher = "Društvo za keramičke materijale Srbije",
journal = "2rd Conference of the Serbian Society for Ceramic Materials",
title = "Chemical stability enhancement of doped BaCe0.9Y0.1O3-δ as an electrolyte for proton conducting SOFCs",
pages = "90",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2337"
}

Radojković, A., Savić, S., Žunić, M., Branković, Z.,& Branković, G.. (2013). Chemical stability enhancement of doped BaCe0.9Y0.1O3-δ as an electrolyte for proton conducting SOFCs. in 2rd Conference of the Serbian Society for Ceramic Materials
Društvo za keramičke materijale Srbije., 90.
https://hdl.handle.net/21.15107/rcub_rimsi_2337

Radojković A, Savić S, Žunić M, Branković Z, Branković G. Chemical stability enhancement of doped BaCe0.9Y0.1O3-δ as an electrolyte for proton conducting SOFCs. in 2rd Conference of the Serbian Society for Ceramic Materials. 2013;:90.
https://hdl.handle.net/21.15107/rcub_rimsi_2337 .

Radojković, Aleksandar, Savić, Slavica, Žunić, Milan, Branković, Zorica, Branković, Goran, "Chemical stability enhancement of doped BaCe0.9Y0.1O3-δ as an electrolyte for proton conducting SOFCs" in 2rd Conference of the Serbian Society for Ceramic Materials (2013):90,
https://hdl.handle.net/21.15107/rcub_rimsi_2337 .