TY  - JOUR
AU  - Rajić, Vladimir
AU  - Stojković Simatović, Ivana
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Novaković, Mirjana
AU  - Popović, Maja
AU  - Škapin, Srečo Davor
AU  - Mojović, Miloš
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Janković Častvan, Ivona
AU  - Marković, Smilja
PY  - 2020
UR  - https://pubs.rsc.org/en/content/articlelanding/2020/cp/d0cp03377d
UR  - https://dais.sanu.ac.rs/123456789/9543
AB  - Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.
PB  - Royal Society of Chemistry
T2  - Physical Chemistry Chemical Physics
T1  - Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry
SP  - 22078
EP  - 22095
VL  - 22
IS  - 38
DO  - 10.1039/D0CP03377D
UR  - https://hdl.handle.net/21.15107/rcub_dais_9543
ER  - 

@article{
author = "Rajić, Vladimir and Stojković Simatović, Ivana and Veselinović, Ljiljana and Belošević Čavor, Jelena and Novaković, Mirjana and Popović, Maja and Škapin, Srečo Davor and Mojović, Miloš and Stojadinović, Stevan and Rac, Vladislav and Janković Častvan, Ivona and Marković, Smilja",
year = "2020",
abstract = "Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.",
publisher = "Royal Society of Chemistry",
journal = "Physical Chemistry Chemical Physics",
title = "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry",
pages = "22078-22095",
volume = "22",
number = "38",
doi = "10.1039/D0CP03377D",
url = "https://hdl.handle.net/21.15107/rcub_dais_9543"
}

Rajić, V., Stojković Simatović, I., Veselinović, L., Belošević Čavor, J., Novaković, M., Popović, M., Škapin, S. D., Mojović, M., Stojadinović, S., Rac, V., Janković Častvan, I.,& Marković, S.. (2020). Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics
Royal Society of Chemistry., 22(38), 22078-22095.
https://doi.org/10.1039/D0CP03377D
https://hdl.handle.net/21.15107/rcub_dais_9543

Rajić V, Stojković Simatović I, Veselinović L, Belošević Čavor J, Novaković M, Popović M, Škapin SD, Mojović M, Stojadinović S, Rac V, Janković Častvan I, Marković S. Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics. 2020;22(38):22078-22095.
doi:10.1039/D0CP03377D
https://hdl.handle.net/21.15107/rcub_dais_9543 .

Rajić, Vladimir, Stojković Simatović, Ivana, Veselinović, Ljiljana, Belošević Čavor, Jelena, Novaković, Mirjana, Popović, Maja, Škapin, Srečo Davor, Mojović, Miloš, Stojadinović, Stevan, Rac, Vladislav, Janković Častvan, Ivona, Marković, Smilja, "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry" in Physical Chemistry Chemical Physics, 22, no. 38 (2020):22078-22095,
https://doi.org/10.1039/D0CP03377D .,
https://hdl.handle.net/21.15107/rcub_dais_9543 .

TY  - JOUR
AU  - Rajić, Vladimir
AU  - Stojković Simatović, Ivana
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Novaković, Mirjana
AU  - Popović, Maja
AU  - Škapin, Srečo Davor
AU  - Mojović, Miloš
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Janković Častvan, Ivona
AU  - Marković, Smilja
PY  - 2020
UR  - https://pubs.rsc.org/en/content/articlelanding/2020/cp/d0cp03377d
UR  - https://dais.sanu.ac.rs/123456789/9544
AB  - Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.
PB  - Royal Society of Chemistry
T2  - Physical Chemistry Chemical Physics
T1  - Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry
SP  - 22078
EP  - 22095
VL  - 22
IS  - 38
DO  - 10.1039/D0CP03377D
UR  - https://hdl.handle.net/21.15107/rcub_dais_9544
ER  - 

@article{
author = "Rajić, Vladimir and Stojković Simatović, Ivana and Veselinović, Ljiljana and Belošević Čavor, Jelena and Novaković, Mirjana and Popović, Maja and Škapin, Srečo Davor and Mojović, Miloš and Stojadinović, Stevan and Rac, Vladislav and Janković Častvan, Ivona and Marković, Smilja",
year = "2020",
abstract = "Eco-friendly and rapid microwave processing of a precipitate was used to produce Fe-doped zinc oxide (Zn1−xFexO, x = 0, 0.05, 0.1, 0.15 and 0.20; ZnO:Fe) nanoparticles, which were tested as catalysts toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in a moderately alkaline solution. The phase composition, crystal structure, morphology, textural properties, surface chemistry, optical properties and band structure were examined to comprehend the influence of Zn2+ partial substitution with Fe3+ on the catalytic activity of ZnO:Fe. Linear sweep voltammetry showed an improved catalytic activity of ZnO:5Fe toward the ORR, compared to pure ZnO, while with increased amounts of the Fe-dopant the activity decreased. The improvement was suggested by a more positive onset potential (0.394 V vs. RHE), current density (0.231 mA cm−2 at 0.150 V vs. RHE), and faster kinetics (Tafel slope, b = 248 mV dec−1), and it may be due to the synergistic effect of (1) a sufficient amount of surface oxygen vacancies, and (2) a certain amount of plate-like particles composed of crystallites with well developed (0001) and (000) facets. Quite the contrary, the OER study showed that the introduction of Fe3+ ions into the ZnO crystal structure resulted in enhanced catalytic activity of all ZnO:Fe samples, compared to pure ZnO, probably due to the modified binding energy and an optimized band structure. With the maximal current density of 1.066 mA cm−2 at 2.216 V vs. RHE, an onset potential of 1.856 V vs. RHE, and the smallest potential difference between the OER and ORR (ΔE = 1.58 V), ZnO:10Fe may be considered a promising bifunctional catalyst toward the OER/ORR in moderately alkaline solution. This study demonstrates that the electrocatalytic activity of ZnO:Fe strongly depends on the defect chemistry and consequently the band structure. Along with providing fundamental insight into the electrocatalytic activity of ZnO:Fe, the study also indicates an optimal stoichiometry for enhanced bifunctional activity toward the OER/ORR, compared to pure ZnO.",
publisher = "Royal Society of Chemistry",
journal = "Physical Chemistry Chemical Physics",
title = "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry",
pages = "22078-22095",
volume = "22",
number = "38",
doi = "10.1039/D0CP03377D",
url = "https://hdl.handle.net/21.15107/rcub_dais_9544"
}

Rajić, V., Stojković Simatović, I., Veselinović, L., Belošević Čavor, J., Novaković, M., Popović, M., Škapin, S. D., Mojović, M., Stojadinović, S., Rac, V., Janković Častvan, I.,& Marković, S.. (2020). Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics
Royal Society of Chemistry., 22(38), 22078-22095.
https://doi.org/10.1039/D0CP03377D
https://hdl.handle.net/21.15107/rcub_dais_9544

Rajić V, Stojković Simatović I, Veselinović L, Belošević Čavor J, Novaković M, Popović M, Škapin SD, Mojović M, Stojadinović S, Rac V, Janković Častvan I, Marković S. Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry. in Physical Chemistry Chemical Physics. 2020;22(38):22078-22095.
doi:10.1039/D0CP03377D
https://hdl.handle.net/21.15107/rcub_dais_9544 .

Rajić, Vladimir, Stojković Simatović, Ivana, Veselinović, Ljiljana, Belošević Čavor, Jelena, Novaković, Mirjana, Popović, Maja, Škapin, Srečo Davor, Mojović, Miloš, Stojadinović, Stevan, Rac, Vladislav, Janković Častvan, Ivona, Marković, Smilja, "Bifunctional catalytic activity of Zn1−xFexO toward the OER/ORR: seeking an optimal stoichiometry" in Physical Chemistry Chemical Physics, 22, no. 38 (2020):22078-22095,
https://doi.org/10.1039/D0CP03377D .,
https://hdl.handle.net/21.15107/rcub_dais_9544 .

TY  - JOUR
AU  - Ivanovski, Valentin N.
AU  - Belošević-Čavor, Jelena
AU  - Rajić, Vladimir
AU  - Umićević, Ana
AU  - Marković, Smilja
AU  - Kusigerski, Vladan
AU  - Mitrić, Miodrag
AU  - Koteski, Vasil
PY  - 2019
UR  - https://aip.scitation.org/doi/10.1063/1.5095837
UR  - https://dais.sanu.ac.rs/123456789/6883
AB  - In order to study the effect of Fe cation substitution on the local structure, defect formation, and hyperfine interactions in ZnO, Mössbauer spectroscopy measurements of the microwave processed Zn1−xFexO (x=0.05, 0.10, 0.15, and 0.20) nanoparticles, together with ab initio calculations, were performed. Complementary information on the distribution of particle size and morphology, as well as magnetic properties, were obtained by X-ray diffraction, transmission electron microscopy, and squid-magnetometry. The selected model for analyzing the Mössbauer spectra of our samples is a distribution of quadrupole splittings. The fitting model with two Lorentz doublets was rejected due to its failure to include larger doublets. The Fe3+ ions do not yield magnetic ordering in the samples at room temperature. The results from first-principles calculations confirm that the major component of the Mössbauer spectra corresponds to the Fe-alloyed ZnO with Zn vacancy in the next nearest neighbor environment. The magnetic measurements are consistent with the description of the distribution of iron ions over the randomly formed clusters in the ZnO host lattice. While at room temperature all the samples are paramagnetic, magnetic interactions cause a transition into a cluster spin-glass state at low temperatures.
PB  - AIP Publishing
T2  - Journal of Applied Physics
T1  - A study of defect structures in Fe-alloyed ZnO: Morphology, magnetism, and hyperfine interactions
SP  - 125703
VL  - 126
IS  - 12
DO  - 10.1063/1.5095837
UR  - https://hdl.handle.net/21.15107/rcub_dais_6883
ER  - 

@article{
author = "Ivanovski, Valentin N. and Belošević-Čavor, Jelena and Rajić, Vladimir and Umićević, Ana and Marković, Smilja and Kusigerski, Vladan and Mitrić, Miodrag and Koteski, Vasil",
year = "2019",
abstract = "In order to study the effect of Fe cation substitution on the local structure, defect formation, and hyperfine interactions in ZnO, Mössbauer spectroscopy measurements of the microwave processed Zn1−xFexO (x=0.05, 0.10, 0.15, and 0.20) nanoparticles, together with ab initio calculations, were performed. Complementary information on the distribution of particle size and morphology, as well as magnetic properties, were obtained by X-ray diffraction, transmission electron microscopy, and squid-magnetometry. The selected model for analyzing the Mössbauer spectra of our samples is a distribution of quadrupole splittings. The fitting model with two Lorentz doublets was rejected due to its failure to include larger doublets. The Fe3+ ions do not yield magnetic ordering in the samples at room temperature. The results from first-principles calculations confirm that the major component of the Mössbauer spectra corresponds to the Fe-alloyed ZnO with Zn vacancy in the next nearest neighbor environment. The magnetic measurements are consistent with the description of the distribution of iron ions over the randomly formed clusters in the ZnO host lattice. While at room temperature all the samples are paramagnetic, magnetic interactions cause a transition into a cluster spin-glass state at low temperatures.",
publisher = "AIP Publishing",
journal = "Journal of Applied Physics",
title = "A study of defect structures in Fe-alloyed ZnO: Morphology, magnetism, and hyperfine interactions",
pages = "125703",
volume = "126",
number = "12",
doi = "10.1063/1.5095837",
url = "https://hdl.handle.net/21.15107/rcub_dais_6883"
}

Ivanovski, V. N., Belošević-Čavor, J., Rajić, V., Umićević, A., Marković, S., Kusigerski, V., Mitrić, M.,& Koteski, V.. (2019). A study of defect structures in Fe-alloyed ZnO: Morphology, magnetism, and hyperfine interactions. in Journal of Applied Physics
AIP Publishing., 126(12), 125703.
https://doi.org/10.1063/1.5095837
https://hdl.handle.net/21.15107/rcub_dais_6883

Ivanovski VN, Belošević-Čavor J, Rajić V, Umićević A, Marković S, Kusigerski V, Mitrić M, Koteski V. A study of defect structures in Fe-alloyed ZnO: Morphology, magnetism, and hyperfine interactions. in Journal of Applied Physics. 2019;126(12):125703.
doi:10.1063/1.5095837
https://hdl.handle.net/21.15107/rcub_dais_6883 .

Ivanovski, Valentin N., Belošević-Čavor, Jelena, Rajić, Vladimir, Umićević, Ana, Marković, Smilja, Kusigerski, Vladan, Mitrić, Miodrag, Koteski, Vasil, "A study of defect structures in Fe-alloyed ZnO: Morphology, magnetism, and hyperfine interactions" in Journal of Applied Physics, 126, no. 12 (2019):125703,
https://doi.org/10.1063/1.5095837 .,
https://hdl.handle.net/21.15107/rcub_dais_6883 .

TY  - CONF
AU  - Marković, Smilja
AU  - Rajić, Vladimir B.
AU  - Stojković Simatović, Ivana
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Ivanovski, Valentin N.
AU  - Novaković, Mirjana
AU  - Škapin, Srečo Davor
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Uskoković, Dragan
PY  - 2019
UR  - https://dais.sanu.ac.rs/123456789/6677
AB  - Even has been under study since 1935, zinc oxide (ZnO) based materials still attract a huge scientific attention. Owing to a wide band gap energy (3.37 eV at room temperature) and a large exciton binding energy (60 meV) ZnO has a variety of application, e.g. in electronics, optoelectronics, spintronics and photocatalysis. Besides, it has been shown that zinc oxide-based materials have a great potential as photoelectrocatalysts in the processes of water splitting, yielding an increased both photocurrent density and photoconversion efficiency. However, with a band gap energy of 3.37 eV, ZnO is restricted to absorb UV light only. This restriction can be overcome by modifying optical properties of zinc oxide particles. During the years different approaches have been applied to modify the visible light photocatalytic activity of ZnO materials, for example: (1) metal and nonmetal ion doping, (2) hydrogenation, (3) the incorporation of crystalline defects in the form of vacancies and interstitials, (4) the modification of particles morphology and surface topology, etc.
In this study we employed 3d metal ion substitution to improve visible light-driven photoactivity of zinc oxide particles. We investigated the influence of Fe concentration in Zn1-xFeyO(1-x+1.5y) nanoparticles on crystal structure, textural, optical and photoelectrocatalytic properties. Zn1-xFeyO(1-x+1.5y) nanoparticles with nominally 5, 10, 15 and 20 at.% of Fe ions were synthesized by microwave processing of a precipitate. The crystal structure and phase purity of the samples were investigated by X-ray diffraction, Raman and ATR-FTIR spectroscopy. Mössbauer spectroscopy was carried out to clarify the valence state of the iron ions in the ZnO crystal structure. Effects of the iron ions concentration on particles morphology and texture properties were observed with field emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM) with elemental mapping, and nitrogen adsorption–desorption isotherm, respectively. The optical properties were studied using UV–Vis diffuse reflectance and photoluminescence (PL) spectroscopy. Photoelectrochemical activity of the Zn1-xFeyO(1-x+1.5y) samples as anode material was evaluated by linear sweep voltammetry in Na2SO4 electrolyte; the oxygen evolution kinetics were determined and compared. In addition, a series of first principles calculations were performed to address the influence of the iron concentration on the electronic structure of Zn1-xFeyO(1-x+1.5y) samples.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of abstracts / Twenty-first Annual Conference YUCOMAT 2019 & Eleventh World Round Table Conference on Sintering WRTCS 2019, Herceg Novi, Montenegro, September 2-6, 2019
T1  - Point defect-enhanced optical and photoelectrochemical water splitting activity of nanostructured Zn1-xFeyO(1-x+1.5y)
SP  - 54
EP  - 54
UR  - https://hdl.handle.net/21.15107/rcub_dais_6677
ER  - 

@conference{
author = "Marković, Smilja and Rajić, Vladimir B. and Stojković Simatović, Ivana and Veselinović, Ljiljana and Belošević Čavor, Jelena and Ivanovski, Valentin N. and Novaković, Mirjana and Škapin, Srečo Davor and Stojadinović, Stevan and Rac, Vladislav and Uskoković, Dragan",
year = "2019",
abstract = "Even has been under study since 1935, zinc oxide (ZnO) based materials still attract a huge scientific attention. Owing to a wide band gap energy (3.37 eV at room temperature) and a large exciton binding energy (60 meV) ZnO has a variety of application, e.g. in electronics, optoelectronics, spintronics and photocatalysis. Besides, it has been shown that zinc oxide-based materials have a great potential as photoelectrocatalysts in the processes of water splitting, yielding an increased both photocurrent density and photoconversion efficiency. However, with a band gap energy of 3.37 eV, ZnO is restricted to absorb UV light only. This restriction can be overcome by modifying optical properties of zinc oxide particles. During the years different approaches have been applied to modify the visible light photocatalytic activity of ZnO materials, for example: (1) metal and nonmetal ion doping, (2) hydrogenation, (3) the incorporation of crystalline defects in the form of vacancies and interstitials, (4) the modification of particles morphology and surface topology, etc.
In this study we employed 3d metal ion substitution to improve visible light-driven photoactivity of zinc oxide particles. We investigated the influence of Fe concentration in Zn1-xFeyO(1-x+1.5y) nanoparticles on crystal structure, textural, optical and photoelectrocatalytic properties. Zn1-xFeyO(1-x+1.5y) nanoparticles with nominally 5, 10, 15 and 20 at.% of Fe ions were synthesized by microwave processing of a precipitate. The crystal structure and phase purity of the samples were investigated by X-ray diffraction, Raman and ATR-FTIR spectroscopy. Mössbauer spectroscopy was carried out to clarify the valence state of the iron ions in the ZnO crystal structure. Effects of the iron ions concentration on particles morphology and texture properties were observed with field emission scanning electron microscopy (FE–SEM), transmission electron microscopy (TEM) with elemental mapping, and nitrogen adsorption–desorption isotherm, respectively. The optical properties were studied using UV–Vis diffuse reflectance and photoluminescence (PL) spectroscopy. Photoelectrochemical activity of the Zn1-xFeyO(1-x+1.5y) samples as anode material was evaluated by linear sweep voltammetry in Na2SO4 electrolyte; the oxygen evolution kinetics were determined and compared. In addition, a series of first principles calculations were performed to address the influence of the iron concentration on the electronic structure of Zn1-xFeyO(1-x+1.5y) samples.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of abstracts / Twenty-first Annual Conference YUCOMAT 2019 & Eleventh World Round Table Conference on Sintering WRTCS 2019, Herceg Novi, Montenegro, September 2-6, 2019",
title = "Point defect-enhanced optical and photoelectrochemical water splitting activity of nanostructured Zn1-xFeyO(1-x+1.5y)",
pages = "54-54",
url = "https://hdl.handle.net/21.15107/rcub_dais_6677"
}

Marković, S., Rajić, V. B., Stojković Simatović, I., Veselinović, L., Belošević Čavor, J., Ivanovski, V. N., Novaković, M., Škapin, S. D., Stojadinović, S., Rac, V.,& Uskoković, D.. (2019). Point defect-enhanced optical and photoelectrochemical water splitting activity of nanostructured Zn1-xFeyO(1-x+1.5y). in Programme and The Book of abstracts / Twenty-first Annual Conference YUCOMAT 2019 & Eleventh World Round Table Conference on Sintering WRTCS 2019, Herceg Novi, Montenegro, September 2-6, 2019
Belgrade : Materials Research Society of Serbia., 54-54.
https://hdl.handle.net/21.15107/rcub_dais_6677

Marković S, Rajić VB, Stojković Simatović I, Veselinović L, Belošević Čavor J, Ivanovski VN, Novaković M, Škapin SD, Stojadinović S, Rac V, Uskoković D. Point defect-enhanced optical and photoelectrochemical water splitting activity of nanostructured Zn1-xFeyO(1-x+1.5y). in Programme and The Book of abstracts / Twenty-first Annual Conference YUCOMAT 2019 & Eleventh World Round Table Conference on Sintering WRTCS 2019, Herceg Novi, Montenegro, September 2-6, 2019. 2019;:54-54.
https://hdl.handle.net/21.15107/rcub_dais_6677 .

Marković, Smilja, Rajić, Vladimir B., Stojković Simatović, Ivana, Veselinović, Ljiljana, Belošević Čavor, Jelena, Ivanovski, Valentin N., Novaković, Mirjana, Škapin, Srečo Davor, Stojadinović, Stevan, Rac, Vladislav, Uskoković, Dragan, "Point defect-enhanced optical and photoelectrochemical water splitting activity of nanostructured Zn1-xFeyO(1-x+1.5y)" in Programme and The Book of abstracts / Twenty-first Annual Conference YUCOMAT 2019 & Eleventh World Round Table Conference on Sintering WRTCS 2019, Herceg Novi, Montenegro, September 2-6, 2019 (2019):54-54,
https://hdl.handle.net/21.15107/rcub_dais_6677 .

TY  - CONF
AU  - Marković, Smilja
AU  - Rajić, Vladimir
AU  - Veselinović, Ljiljana
AU  - Stojković Simatović, Ivana
AU  - Belošević Čavor, Jelena
AU  - Škapin, Srečo Davor
AU  - Kovač, Janez
AU  - Nikolić, Marko G.
AU  - Uskoković, Dragan
PY  - 2019
UR  - https://dais.sanu.ac.rs/123456789/6997
AB  - During the last decade zinc oxide (ZnO) has attracted considerable attention as a promising material for electronic, optoelectronic and spintronic devices. ZnO has a wide bandgap (3.37 eV at room temperature) and relatively large exciton binding energy (60 meV) which enables multifunctional application. Until now ZnO-based materials have been used as UV and blue light emitters, varistors, thermistors, semiconductors, photoanodes, and other. Various approaches have been applied to improve functional properties of zinc oxide, such as: fabrication of ZnO-based heterojunction particles, particles’ surface sensitization, hydrogenation, etc. It has been found that intrinsic defects (vacancies, interstitials and antisites) in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, correlation of the intrinsic defects concentration with optical and electrical properties of ZnO materials is of great importance for their further application in opto-electronic devices. In this study we investigated the influence of intrinsic defects concentration on the optical, electrical and photoelectrocatalytic properties of ZnO materials. To obtain ZnO powder with a high concentration of intrinsic defects microwave processing of precipitate was employed, while for further varying of defects concentration, the powder was thermally treated in three different atmospheres: air, argon and oxygen. The ZnO powder was uniaxially pressed (P = 100 MPa) in cylindrical compacts (R= 6 mm and h approx. 3 mm) which were sintered in different atmospheres by heating rate of 10 °/min up to 1100 °C, and with dwell time of 1 h. To study a crystal structure of ZnO samples XRD and Raman spectroscopy were used, while for microstructural investigation field emission scanning electron micrographs were recorded. Optical properties were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of intrinsic defects in ZnO crystal lattice on functional properties, XPS, photoluminescence, electroluminescence and electrochemical impedance spectra were analyzed. A detailed analysis of the experimental results imply that a high concentration of intrinsic defects, in particular oxygen vacancies, is of the greatest importance for tunable light-emitting diode application and significant for the photoanode properties. To support our experimental observation we performed ab initio calculations based on density functional theory (DFT).
PB  - Budapest : [s. n.]
C3  - Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest
T1  - Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration
SP  - 11
EP  - 11
UR  - https://hdl.handle.net/21.15107/rcub_dais_6997
ER  - 

@conference{
author = "Marković, Smilja and Rajić, Vladimir and Veselinović, Ljiljana and Stojković Simatović, Ivana and Belošević Čavor, Jelena and Škapin, Srečo Davor and Kovač, Janez and Nikolić, Marko G. and Uskoković, Dragan",
year = "2019",
abstract = "During the last decade zinc oxide (ZnO) has attracted considerable attention as a promising material for electronic, optoelectronic and spintronic devices. ZnO has a wide bandgap (3.37 eV at room temperature) and relatively large exciton binding energy (60 meV) which enables multifunctional application. Until now ZnO-based materials have been used as UV and blue light emitters, varistors, thermistors, semiconductors, photoanodes, and other. Various approaches have been applied to improve functional properties of zinc oxide, such as: fabrication of ZnO-based heterojunction particles, particles’ surface sensitization, hydrogenation, etc. It has been found that intrinsic defects (vacancies, interstitials and antisites) in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, correlation of the intrinsic defects concentration with optical and electrical properties of ZnO materials is of great importance for their further application in opto-electronic devices. In this study we investigated the influence of intrinsic defects concentration on the optical, electrical and photoelectrocatalytic properties of ZnO materials. To obtain ZnO powder with a high concentration of intrinsic defects microwave processing of precipitate was employed, while for further varying of defects concentration, the powder was thermally treated in three different atmospheres: air, argon and oxygen. The ZnO powder was uniaxially pressed (P = 100 MPa) in cylindrical compacts (R= 6 mm and h approx. 3 mm) which were sintered in different atmospheres by heating rate of 10 °/min up to 1100 °C, and with dwell time of 1 h. To study a crystal structure of ZnO samples XRD and Raman spectroscopy were used, while for microstructural investigation field emission scanning electron micrographs were recorded. Optical properties were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of intrinsic defects in ZnO crystal lattice on functional properties, XPS, photoluminescence, electroluminescence and electrochemical impedance spectra were analyzed. A detailed analysis of the experimental results imply that a high concentration of intrinsic defects, in particular oxygen vacancies, is of the greatest importance for tunable light-emitting diode application and significant for the photoanode properties. To support our experimental observation we performed ab initio calculations based on density functional theory (DFT).",
publisher = "Budapest : [s. n.]",
journal = "Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest",
title = "Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration",
pages = "11-11",
url = "https://hdl.handle.net/21.15107/rcub_dais_6997"
}

Marković, S., Rajić, V., Veselinović, L., Stojković Simatović, I., Belošević Čavor, J., Škapin, S. D., Kovač, J., Nikolić, M. G.,& Uskoković, D.. (2019). Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration. in Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest
Budapest : [s. n.]., 11-11.
https://hdl.handle.net/21.15107/rcub_dais_6997

Marković S, Rajić V, Veselinović L, Stojković Simatović I, Belošević Čavor J, Škapin SD, Kovač J, Nikolić MG, Uskoković D. Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration. in Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest. 2019;:11-11.
https://hdl.handle.net/21.15107/rcub_dais_6997 .

Marković, Smilja, Rajić, Vladimir, Veselinović, Ljiljana, Stojković Simatović, Ivana, Belošević Čavor, Jelena, Škapin, Srečo Davor, Kovač, Janez, Nikolić, Marko G., Uskoković, Dragan, "Tuning the optical, electrical and photoelectrocatalytic properties of Zno materials by varying of intrinsic defects concentration" in Abstracts / International Workshop on Woman in Ceramic Science (WoCeram2019), April 7-9, 2019/ Budapest, Hungary, Novotel Danube Budapest (2019):11-11,
https://hdl.handle.net/21.15107/rcub_dais_6997 .

TY  - CONF
AU  - Marković, Smilja
AU  - Rajić, Vladimir B.
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Škapin, Srečo Davor
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Lević, Steva
AU  - Mojović, Miloš
AU  - Uskoković, Dragan
PY  - 2016
UR  - https://dais.sanu.ac.rs/123456789/902
AB  - Zinc oxide is one of the most studied materials due to its wide bandgap (3.37 eV) and large exciton binding energy (60 meV) which enables application in electronics, optoelectronics and spintronics. In the forms of single crystal and thin-film ZnO are used as UV and blue light emitter, while sintered ZnO-based ceramics are important as varistors, thermistors or semiconductors. It has been found that point defects in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Neutral oxygen vacancies are considered to be a major component of the defect structure of ZnO. Thus, correlation of the oxygen vacancies concentration with band gap energy of ZnO product is important to its application in optoelectronic devices. In this study we investigated the influence of point defects concentration in ZnO crystal structure on its optical and photocatalytic properties. We analyzed ZnO powders prepared by different techniques: (a) microwave processing of precipitate and (b) hydrothermal processing, which yield different ordered crystal structure. To increase a concentration of the point defects in the crystal structure, the powders were sintered in air atmosphere by heating rate of 10 °/min up to 1100 °C, with dwell time of 1 h. The crystal structure, average crystallite size and phase purity of the ZnO ceramics were determined by X-ray diffraction and Raman spectroscopy. The optical properties, in particular, absorption capacity and bang gap energy, were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of microstructures and point defects in ZnO crystal lattice, which are receptive for luminescence and photocatalytic activity of this functional oxide, photoluminescence (PL), photoluminescence excitation (PLE) and EPR spectra were analyzed. The influence of point defects concentration in the ZnO crystal structure on photocatalytic properties was examined via decolorization of methylene blue under direct sunlight irradiation. Correlation between amount of the point defects, absorption capacity and photocatalytic efficiency were established. In order to clarify the experimental results ab initio calculations based on density functional theory (DFT) were performed.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Eighteenth Annual Conference YUCOMAT 2016, Herceg Novi, September 5-10, 2016
T1  - Influence of point defects concentration on optical and photocatalytic properties of ZnO ceramics
SP  - 34
EP  - 34
UR  - https://hdl.handle.net/21.15107/rcub_dais_902
ER  - 

@conference{
author = "Marković, Smilja and Rajić, Vladimir B. and Veselinović, Ljiljana and Belošević Čavor, Jelena and Škapin, Srečo Davor and Stojadinović, Stevan and Rac, Vladislav and Lević, Steva and Mojović, Miloš and Uskoković, Dragan",
year = "2016",
abstract = "Zinc oxide is one of the most studied materials due to its wide bandgap (3.37 eV) and large exciton binding energy (60 meV) which enables application in electronics, optoelectronics and spintronics. In the forms of single crystal and thin-film ZnO are used as UV and blue light emitter, while sintered ZnO-based ceramics are important as varistors, thermistors or semiconductors. It has been found that point defects in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Neutral oxygen vacancies are considered to be a major component of the defect structure of ZnO. Thus, correlation of the oxygen vacancies concentration with band gap energy of ZnO product is important to its application in optoelectronic devices. In this study we investigated the influence of point defects concentration in ZnO crystal structure on its optical and photocatalytic properties. We analyzed ZnO powders prepared by different techniques: (a) microwave processing of precipitate and (b) hydrothermal processing, which yield different ordered crystal structure. To increase a concentration of the point defects in the crystal structure, the powders were sintered in air atmosphere by heating rate of 10 °/min up to 1100 °C, with dwell time of 1 h. The crystal structure, average crystallite size and phase purity of the ZnO ceramics were determined by X-ray diffraction and Raman spectroscopy. The optical properties, in particular, absorption capacity and bang gap energy, were studied using UV–Vis diffuse reflectance spectroscopy. To reveal the role of microstructures and point defects in ZnO crystal lattice, which are receptive for luminescence and photocatalytic activity of this functional oxide, photoluminescence (PL), photoluminescence excitation (PLE) and EPR spectra were analyzed. The influence of point defects concentration in the ZnO crystal structure on photocatalytic properties was examined via decolorization of methylene blue under direct sunlight irradiation. Correlation between amount of the point defects, absorption capacity and photocatalytic efficiency were established. In order to clarify the experimental results ab initio calculations based on density functional theory (DFT) were performed.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Eighteenth Annual Conference YUCOMAT 2016, Herceg Novi, September 5-10, 2016",
title = "Influence of point defects concentration on optical and photocatalytic properties of ZnO ceramics",
pages = "34-34",
url = "https://hdl.handle.net/21.15107/rcub_dais_902"
}

Marković, S., Rajić, V. B., Veselinović, L., Belošević Čavor, J., Škapin, S. D., Stojadinović, S., Rac, V., Lević, S., Mojović, M.,& Uskoković, D.. (2016). Influence of point defects concentration on optical and photocatalytic properties of ZnO ceramics. in Programme and The Book of Abstracts / Eighteenth Annual Conference YUCOMAT 2016, Herceg Novi, September 5-10, 2016
Belgrade : Materials Research Society of Serbia., 34-34.
https://hdl.handle.net/21.15107/rcub_dais_902

Marković S, Rajić VB, Veselinović L, Belošević Čavor J, Škapin SD, Stojadinović S, Rac V, Lević S, Mojović M, Uskoković D. Influence of point defects concentration on optical and photocatalytic properties of ZnO ceramics. in Programme and The Book of Abstracts / Eighteenth Annual Conference YUCOMAT 2016, Herceg Novi, September 5-10, 2016. 2016;:34-34.
https://hdl.handle.net/21.15107/rcub_dais_902 .

Marković, Smilja, Rajić, Vladimir B., Veselinović, Ljiljana, Belošević Čavor, Jelena, Škapin, Srečo Davor, Stojadinović, Stevan, Rac, Vladislav, Lević, Steva, Mojović, Miloš, Uskoković, Dragan, "Influence of point defects concentration on optical and photocatalytic properties of ZnO ceramics" in Programme and The Book of Abstracts / Eighteenth Annual Conference YUCOMAT 2016, Herceg Novi, September 5-10, 2016 (2016):34-34,
https://hdl.handle.net/21.15107/rcub_dais_902 .

TY  - JOUR
AU  - Marković, Smilja
AU  - Rajić, Vladimir B.
AU  - Stanković, Ana
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Batalović, Katarina
AU  - Abazović, Nadica
AU  - Škapin, Srečo Davor
AU  - Uskoković, Dragan
PY  - 2016
UR  - https://dais.sanu.ac.rs/123456789/2317
AB  - ZnO spheroidal nanoparticles, synthesized by microwave processing, were used for preparation of composites with polyethylene oxide (PEO). The phase purity and crystal structure of the composites were investigated by X-ray diffraction (XRD) and Raman spectroscopy. The composites’ particles morphology and size distributions were studied by FE-SEM and laser diffraction particle size analyzer, respectively. The optical properties were studied using UV–Vis diffuse reflectance and photoluminescence spectroscopy. It is found that in the wavelength range 550–800 nm, ZnO and ZnO/PEO composites absorb about 50% of the incident light intensity. Also red-shift of band gap energy (0.12–0.15 eV) compared to bulk ZnO was determined. The effect of PEO molecular weights, 200,000, 600,000 and 900,000 g/mol, on photocatalytic activity of ZnO/PEO composites were examined via de-colorization of methylene blue (MB) under direct sunlight irradiation. A large efficiency of MB de-colorization was found after 6 h of irradiation. The enhanced photocatalytic activity of ZnO/PEO composites is attributed to the: (1) lattice defects introduced in ZnO crystal structure by rapid microwave processing, and (2) presence of PEO as a source of oxygen interstitials. In order to confirm and further clarify the experimental results ab initio calculations based on density functional theory (DFT) were performed.
PB  - Elsevier
T2  - Solar Energy
T1  - Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites
SP  - 124
EP  - 135
VL  - 127
DO  - 10.1016/j.solener.2016.01.026
UR  - https://hdl.handle.net/21.15107/rcub_dais_2317
ER  - 

@article{
author = "Marković, Smilja and Rajić, Vladimir B. and Stanković, Ana and Veselinović, Ljiljana and Belošević Čavor, Jelena and Batalović, Katarina and Abazović, Nadica and Škapin, Srečo Davor and Uskoković, Dragan",
year = "2016",
abstract = "ZnO spheroidal nanoparticles, synthesized by microwave processing, were used for preparation of composites with polyethylene oxide (PEO). The phase purity and crystal structure of the composites were investigated by X-ray diffraction (XRD) and Raman spectroscopy. The composites’ particles morphology and size distributions were studied by FE-SEM and laser diffraction particle size analyzer, respectively. The optical properties were studied using UV–Vis diffuse reflectance and photoluminescence spectroscopy. It is found that in the wavelength range 550–800 nm, ZnO and ZnO/PEO composites absorb about 50% of the incident light intensity. Also red-shift of band gap energy (0.12–0.15 eV) compared to bulk ZnO was determined. The effect of PEO molecular weights, 200,000, 600,000 and 900,000 g/mol, on photocatalytic activity of ZnO/PEO composites were examined via de-colorization of methylene blue (MB) under direct sunlight irradiation. A large efficiency of MB de-colorization was found after 6 h of irradiation. The enhanced photocatalytic activity of ZnO/PEO composites is attributed to the: (1) lattice defects introduced in ZnO crystal structure by rapid microwave processing, and (2) presence of PEO as a source of oxygen interstitials. In order to confirm and further clarify the experimental results ab initio calculations based on density functional theory (DFT) were performed.",
publisher = "Elsevier",
journal = "Solar Energy",
title = "Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites",
pages = "124-135",
volume = "127",
doi = "10.1016/j.solener.2016.01.026",
url = "https://hdl.handle.net/21.15107/rcub_dais_2317"
}

Marković, S., Rajić, V. B., Stanković, A., Veselinović, L., Belošević Čavor, J., Batalović, K., Abazović, N., Škapin, S. D.,& Uskoković, D.. (2016). Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites. in Solar Energy
Elsevier., 127, 124-135.
https://doi.org/10.1016/j.solener.2016.01.026
https://hdl.handle.net/21.15107/rcub_dais_2317

Marković S, Rajić VB, Stanković A, Veselinović L, Belošević Čavor J, Batalović K, Abazović N, Škapin SD, Uskoković D. Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites. in Solar Energy. 2016;127:124-135.
doi:10.1016/j.solener.2016.01.026
https://hdl.handle.net/21.15107/rcub_dais_2317 .

Marković, Smilja, Rajić, Vladimir B., Stanković, Ana, Veselinović, Ljiljana, Belošević Čavor, Jelena, Batalović, Katarina, Abazović, Nadica, Škapin, Srečo Davor, Uskoković, Dragan, "Effect of PEO molecular weight on sunlight induced photocatalytic activity of ZnO/PEO composites" in Solar Energy, 127 (2016):124-135,
https://doi.org/10.1016/j.solener.2016.01.026 .,
https://hdl.handle.net/21.15107/rcub_dais_2317 .

TY  - CONF
AU  - Marković, Smilja
AU  - Stanković, Ana
AU  - Veselinović, Ljiljana
AU  - Belošević Čavor, Jelena
AU  - Škapin, Srečo Davor
AU  - Stojadinović, Stevan
AU  - Rac, Vladislav
AU  - Lević, Steva
AU  - Janković Častvan, Ivona
AU  - Uskoković, Dragan
PY  - 2015
UR  - https://dais.sanu.ac.rs/123456789/831
AB  - Zinc oxide is one of the most studied materials due to its potential applications in electronics, optoelectronics and spintronics. In the forms of single crystal and thin-film ZnO could be used as UV and blue light emitter, while sintered ZnO-based ceramics are important as varistors, thermistors or wide-band gap semiconductors. Intrinsic defects, such as vacancies, interstitials and antisites, in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, understanding the behavior of intrinsic defects during densification of ZnO ceramics as well as correlation of the defects with band gap energy of final product is important to its application in opto-electronic devices.
In this study, the influence of point defects concentration on the densification process and optical properties of ZnO sintered ceramics was investigated. To obtain ZnO sintered ceramics with variety of point defects concentration we employed two starting powders with a different crystal structure ordering, as well different morphology and specific surface area. Sinterability of the powders was investigated by thermo mechanical analyzer; shrinkage data, collected in axial (h) direction during non-isothermal sintering with heating rates of 5, 10 and 20 °/min, were used to calculate activation energy of sintering process. Sintering of uniaxially pressed (P = 100 MPa) cylindrical compacts (ø 6 mm and h ≈ 3 mm) were done in air atmosphere by heating rate of 10 °/min up to 1100 and 1200 °C, and dwell time of 2 h. To study a crystal structure of the sintered samples XRD and Raman spectroscopy were used, for microstructural investigation field emission scanning electron micrographs were recorded while optical properties were determined by UV-Vis diffuse reflectance and photoluminescence spectroscopy. A detailed study shows that point defect strongly influenced densification process as well optical properties. Sintered ZnO ceramic with a high crystal defect concentration and nanosized grains shows band gap energy of about 2 eV while band gap energy increased with a decrease of defect concentration.
PB  - Belgrade : Materials Research Society of Serbia
C3  - Programme and The Book of Abstracts / Seventeenth Annual Conference YUCOMAT 205, Herceg Novi, August 31– September 4, 2015
T1  - Influence of Point Defects Concentration on Densification Process and Optical Properties of Sintered ZnO Ceramics
SP  - 61
EP  - 61
UR  - https://hdl.handle.net/21.15107/rcub_dais_831
ER  - 

@conference{
author = "Marković, Smilja and Stanković, Ana and Veselinović, Ljiljana and Belošević Čavor, Jelena and Škapin, Srečo Davor and Stojadinović, Stevan and Rac, Vladislav and Lević, Steva and Janković Častvan, Ivona and Uskoković, Dragan",
year = "2015",
abstract = "Zinc oxide is one of the most studied materials due to its potential applications in electronics, optoelectronics and spintronics. In the forms of single crystal and thin-film ZnO could be used as UV and blue light emitter, while sintered ZnO-based ceramics are important as varistors, thermistors or wide-band gap semiconductors. Intrinsic defects, such as vacancies, interstitials and antisites, in the crystal structure of a ZnO strongly influenced its electrical and optical properties. Thus, understanding the behavior of intrinsic defects during densification of ZnO ceramics as well as correlation of the defects with band gap energy of final product is important to its application in opto-electronic devices.
In this study, the influence of point defects concentration on the densification process and optical properties of ZnO sintered ceramics was investigated. To obtain ZnO sintered ceramics with variety of point defects concentration we employed two starting powders with a different crystal structure ordering, as well different morphology and specific surface area. Sinterability of the powders was investigated by thermo mechanical analyzer; shrinkage data, collected in axial (h) direction during non-isothermal sintering with heating rates of 5, 10 and 20 °/min, were used to calculate activation energy of sintering process. Sintering of uniaxially pressed (P = 100 MPa) cylindrical compacts (ø 6 mm and h ≈ 3 mm) were done in air atmosphere by heating rate of 10 °/min up to 1100 and 1200 °C, and dwell time of 2 h. To study a crystal structure of the sintered samples XRD and Raman spectroscopy were used, for microstructural investigation field emission scanning electron micrographs were recorded while optical properties were determined by UV-Vis diffuse reflectance and photoluminescence spectroscopy. A detailed study shows that point defect strongly influenced densification process as well optical properties. Sintered ZnO ceramic with a high crystal defect concentration and nanosized grains shows band gap energy of about 2 eV while band gap energy increased with a decrease of defect concentration.",
publisher = "Belgrade : Materials Research Society of Serbia",
journal = "Programme and The Book of Abstracts / Seventeenth Annual Conference YUCOMAT 205, Herceg Novi, August 31– September 4, 2015",
title = "Influence of Point Defects Concentration on Densification Process and Optical Properties of Sintered ZnO Ceramics",
pages = "61-61",
url = "https://hdl.handle.net/21.15107/rcub_dais_831"
}

Marković, S., Stanković, A., Veselinović, L., Belošević Čavor, J., Škapin, S. D., Stojadinović, S., Rac, V., Lević, S., Janković Častvan, I.,& Uskoković, D.. (2015). Influence of Point Defects Concentration on Densification Process and Optical Properties of Sintered ZnO Ceramics. in Programme and The Book of Abstracts / Seventeenth Annual Conference YUCOMAT 205, Herceg Novi, August 31– September 4, 2015
Belgrade : Materials Research Society of Serbia., 61-61.
https://hdl.handle.net/21.15107/rcub_dais_831

Marković S, Stanković A, Veselinović L, Belošević Čavor J, Škapin SD, Stojadinović S, Rac V, Lević S, Janković Častvan I, Uskoković D. Influence of Point Defects Concentration on Densification Process and Optical Properties of Sintered ZnO Ceramics. in Programme and The Book of Abstracts / Seventeenth Annual Conference YUCOMAT 205, Herceg Novi, August 31– September 4, 2015. 2015;:61-61.
https://hdl.handle.net/21.15107/rcub_dais_831 .

Marković, Smilja, Stanković, Ana, Veselinović, Ljiljana, Belošević Čavor, Jelena, Škapin, Srečo Davor, Stojadinović, Stevan, Rac, Vladislav, Lević, Steva, Janković Častvan, Ivona, Uskoković, Dragan, "Influence of Point Defects Concentration on Densification Process and Optical Properties of Sintered ZnO Ceramics" in Programme and The Book of Abstracts / Seventeenth Annual Conference YUCOMAT 205, Herceg Novi, August 31– September 4, 2015 (2015):61-61,
https://hdl.handle.net/21.15107/rcub_dais_831 .