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  - 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  - JOUR
AU  - Cekić, Božidar
AU  - Ćirić, Katarina
AU  - Iordoc, Mihail
AU  - Marković, Smilja
AU  - Mitrić, Miodrag
PY  - 2013
UR  - https://dais.sanu.ac.rs/123456789/342
AB  - The kinetics of hydrogen absorption in Zr-based alloys Zr–2.5Nb, Zr–10Nb, Zr–2.5Nb–3Ta and Zr–10Nb–12Ta have been investigated in the temperature range 673–973 K at 1 bar hydrogen pressure. The improvement in hydrogen kinetics and a slight decrease of maximal amount of hydrogen absorbed were observed upon cycling. The rate determining steps are as follows: geometrical contraction for all samples except Zr–10Nb–12Ta; diffusion in the beginning for Zr–10Nb at 973 K Zr–2.5Nb–3Ta at 673 K and 973 K; first order reaction Zr–10Nb–12Ta at all temperatures. The amount of additives, Nb and Ta, is found to have major influence on the mechanism of the absorption process.
PB  - Elsevier
T2  - Journal of Alloys and Compounds
T1  - Kinetics of hydrogen absorption in Zr-based alloys
SP  - 162
EP  - 166
VL  - 559
DO  - 10.1016/j.jallcom.2013.01.104
UR  - https://hdl.handle.net/21.15107/rcub_dais_342
ER  - 

@article{
author = "Cekić, Božidar and Ćirić, Katarina and Iordoc, Mihail and Marković, Smilja and Mitrić, Miodrag",
year = "2013",
abstract = "The kinetics of hydrogen absorption in Zr-based alloys Zr–2.5Nb, Zr–10Nb, Zr–2.5Nb–3Ta and Zr–10Nb–12Ta have been investigated in the temperature range 673–973 K at 1 bar hydrogen pressure. The improvement in hydrogen kinetics and a slight decrease of maximal amount of hydrogen absorbed were observed upon cycling. The rate determining steps are as follows: geometrical contraction for all samples except Zr–10Nb–12Ta; diffusion in the beginning for Zr–10Nb at 973 K Zr–2.5Nb–3Ta at 673 K and 973 K; first order reaction Zr–10Nb–12Ta at all temperatures. The amount of additives, Nb and Ta, is found to have major influence on the mechanism of the absorption process.",
publisher = "Elsevier",
journal = "Journal of Alloys and Compounds",
title = "Kinetics of hydrogen absorption in Zr-based alloys",
pages = "162-166",
volume = "559",
doi = "10.1016/j.jallcom.2013.01.104",
url = "https://hdl.handle.net/21.15107/rcub_dais_342"
}

Cekić, B., Ćirić, K., Iordoc, M., Marković, S.,& Mitrić, M.. (2013). Kinetics of hydrogen absorption in Zr-based alloys. in Journal of Alloys and Compounds
Elsevier., 559, 162-166.
https://doi.org/10.1016/j.jallcom.2013.01.104
https://hdl.handle.net/21.15107/rcub_dais_342

Cekić B, Ćirić K, Iordoc M, Marković S, Mitrić M. Kinetics of hydrogen absorption in Zr-based alloys. in Journal of Alloys and Compounds. 2013;559:162-166.
doi:10.1016/j.jallcom.2013.01.104
https://hdl.handle.net/21.15107/rcub_dais_342 .

Cekić, Božidar, Ćirić, Katarina, Iordoc, Mihail, Marković, Smilja, Mitrić, Miodrag, "Kinetics of hydrogen absorption in Zr-based alloys" in Journal of Alloys and Compounds, 559 (2013):162-166,
https://doi.org/10.1016/j.jallcom.2013.01.104 .,
https://hdl.handle.net/21.15107/rcub_dais_342 .