TY  - JOUR
AU  - Srivastava, Alok M.
AU  - Brik, Mikhail G.
AU  - Ma, Chong-Geng
AU  - Beers, William W.
AU  - Cohen, William E.
AU  - Piasecki, Michal
PY  - 2024
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/13190
AB  - The spectroscopic properties of the Mn4+ ion are investigated in the series of isostructural double perovskite compounds, Ba2BTaO6 (B = Y, Lu, Sc). A comparison of these properties highlights the influence of covalent bonding within the perovskite framework and the degree of order between the B3+–Ta cations on the energy and intensity of the Mn4+2E → 4A2 emission transition (R-line). These two parameters of the emission spectrum are of importance for practical application since they determine the phosphor luminous efficacy. The influence of covalent bonding within the corner shared BO6/2 and TaO6/2 perovskite framework on the energy of the R-line energy is investigated. From the spectroscopic data, we have derived information on the influence of the degree of order between the B3+ and Ta5+ cations on the intensity of the R-line. The lowest energy and the highest intensity of the R-line are found in the double perovskite, Ba2ScTaO6. The purpose of this work is to propose for first time an explanation of these effects in the considered double perovskites. The obtained results are useful guidelines for practical improvement and tuning of key parameters of phosphors to the desired values.
T2  - The Journal of Physical Chemistry Letters
T1  - Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc)
VL  - 15
SP  - 4175
EP  - 4184
DO  - 10.1021/acs.jpclett.4c00205
ER  - 

@article{
author = "Srivastava, Alok M. and Brik, Mikhail G. and Ma, Chong-Geng and Beers, William W. and Cohen, William E. and Piasecki, Michal",
year = "2024",
abstract = "The spectroscopic properties of the Mn4+ ion are investigated in the series of isostructural double perovskite compounds, Ba2BTaO6 (B = Y, Lu, Sc). A comparison of these properties highlights the influence of covalent bonding within the perovskite framework and the degree of order between the B3+–Ta cations on the energy and intensity of the Mn4+2E → 4A2 emission transition (R-line). These two parameters of the emission spectrum are of importance for practical application since they determine the phosphor luminous efficacy. The influence of covalent bonding within the corner shared BO6/2 and TaO6/2 perovskite framework on the energy of the R-line energy is investigated. From the spectroscopic data, we have derived information on the influence of the degree of order between the B3+ and Ta5+ cations on the intensity of the R-line. The lowest energy and the highest intensity of the R-line are found in the double perovskite, Ba2ScTaO6. The purpose of this work is to propose for first time an explanation of these effects in the considered double perovskites. The obtained results are useful guidelines for practical improvement and tuning of key parameters of phosphors to the desired values.",
journal = "The Journal of Physical Chemistry Letters",
title = "Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc)",
volume = "15",
pages = "4175-4184",
doi = "10.1021/acs.jpclett.4c00205"
}

Srivastava, A. M., Brik, M. G., Ma, C., Beers, W. W., Cohen, W. E.,& Piasecki, M.. (2024). Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc). in The Journal of Physical Chemistry Letters, 15, 4175-4184.
https://doi.org/10.1021/acs.jpclett.4c00205

Srivastava AM, Brik MG, Ma C, Beers WW, Cohen WE, Piasecki M. Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc). in The Journal of Physical Chemistry Letters. 2024;15:4175-4184.
doi:10.1021/acs.jpclett.4c00205 .

Srivastava, Alok M., Brik, Mikhail G., Ma, Chong-Geng, Beers, William W., Cohen, William E., Piasecki, Michal, "Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn4+ Luminescence in the Double Perovskites, Ba2BTaO6 (B = Y, Lu, Sc)" in The Journal of Physical Chemistry Letters, 15 (2024):4175-4184,
https://doi.org/10.1021/acs.jpclett.4c00205 . .

TY  - JOUR
AU  - Racu, Andrei V.
AU  - Ristić, Zoran
AU  - Ćirić, Aleksandar
AU  - Ðorđević, Vesna
AU  - Buse, Gabriel
AU  - Poienar, Maria
AU  - Gutmann, Michael J.
AU  - Ivashko, Oleh
AU  - Stef, Marius
AU  - Vizman, Daniel
AU  - Dramićanin, Miroslav
AU  - Piasecki, Michal
AU  - Brik, Mikhail G.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10561
AB  - The understanding of complex relationships between luminescent properties, local symmetry of an emitting center, and the host crystal structure provides a better insight into optical properties of materials. In this work, the alkaline earths CaF2 and BaF2 fluoride crystals doped with 0.1 mol% ErF3 were investigated. The crystals structure has been studied using a synchrotron and laboratory X-ray diffraction. The C3v and C4v sites symmetry were determined using erbium probed high resolution emission spectroscopy (HRPL) at low temperature (LT) of 10 K. The considerable difference in room temperature (RT) optical properties for CaF2 compared to BaF2 crystals was observed. Such difference in absorption intensity of 4.7 times of erbium 4G11/2 manifold in UV, and 7.5 times in green emission from 4S3/2 manifold, could be due to the distinction in the host crystals cationic radius (ΔrCa,Ba) and the dopant-host ionic radius (ΔrCa-Er, ΔrBa-Er). Those Δr differences influence the structure and lead to the following symmetry formation: In CaF2, the C4v and C3v isolated centers were identified, with the determined Er3+- F−i bond lengths of 2.734 Å and 4.735 Å respectively; In BaF2, only C3v isolated centers were identified with the determined Er3+- F−i bond lengths of 5.380 Å. The present work is the first study that takes into account correlations of optical properties, the local symmetry and the structure in mentioned fluorides crystals, and it could be a step forward in the lanthanide doped optical materials systematics.
T2  - Optical Materials
T1  - Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy
VL  - 136
SP  - 113337
DO  - 10.1016/j.optmat.2022.113337
ER  - 

@article{
author = "Racu, Andrei V. and Ristić, Zoran and Ćirić, Aleksandar and Ðorđević, Vesna and Buse, Gabriel and Poienar, Maria and Gutmann, Michael J. and Ivashko, Oleh and Stef, Marius and Vizman, Daniel and Dramićanin, Miroslav and Piasecki, Michal and Brik, Mikhail G.",
year = "2023",
abstract = "The understanding of complex relationships between luminescent properties, local symmetry of an emitting center, and the host crystal structure provides a better insight into optical properties of materials. In this work, the alkaline earths CaF2 and BaF2 fluoride crystals doped with 0.1 mol% ErF3 were investigated. The crystals structure has been studied using a synchrotron and laboratory X-ray diffraction. The C3v and C4v sites symmetry were determined using erbium probed high resolution emission spectroscopy (HRPL) at low temperature (LT) of 10 K. The considerable difference in room temperature (RT) optical properties for CaF2 compared to BaF2 crystals was observed. Such difference in absorption intensity of 4.7 times of erbium 4G11/2 manifold in UV, and 7.5 times in green emission from 4S3/2 manifold, could be due to the distinction in the host crystals cationic radius (ΔrCa,Ba) and the dopant-host ionic radius (ΔrCa-Er, ΔrBa-Er). Those Δr differences influence the structure and lead to the following symmetry formation: In CaF2, the C4v and C3v isolated centers were identified, with the determined Er3+- F−i bond lengths of 2.734 Å and 4.735 Å respectively; In BaF2, only C3v isolated centers were identified with the determined Er3+- F−i bond lengths of 5.380 Å. The present work is the first study that takes into account correlations of optical properties, the local symmetry and the structure in mentioned fluorides crystals, and it could be a step forward in the lanthanide doped optical materials systematics.",
journal = "Optical Materials",
title = "Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy",
volume = "136",
pages = "113337",
doi = "10.1016/j.optmat.2022.113337"
}

Racu, A. V., Ristić, Z., Ćirić, A., Ðorđević, V., Buse, G., Poienar, M., Gutmann, M. J., Ivashko, O., Stef, M., Vizman, D., Dramićanin, M., Piasecki, M.,& Brik, M. G.. (2023). Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy. in Optical Materials, 136, 113337.
https://doi.org/10.1016/j.optmat.2022.113337

Racu AV, Ristić Z, Ćirić A, Ðorđević V, Buse G, Poienar M, Gutmann MJ, Ivashko O, Stef M, Vizman D, Dramićanin M, Piasecki M, Brik MG. Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy. in Optical Materials. 2023;136:113337.
doi:10.1016/j.optmat.2022.113337 .

Racu, Andrei V., Ristić, Zoran, Ćirić, Aleksandar, Ðorđević, Vesna, Buse, Gabriel, Poienar, Maria, Gutmann, Michael J., Ivashko, Oleh, Stef, Marius, Vizman, Daniel, Dramićanin, Miroslav, Piasecki, Michal, Brik, Mikhail G., "Analysis of site symmetries of Er3+ doped CaF2 and BaF2 crystals by high resolution photoluminescence spectroscopy" in Optical Materials, 136 (2023):113337,
https://doi.org/10.1016/j.optmat.2022.113337 . .

TY  - JOUR
AU  - Antić, Željka
AU  - Đorđević, Vesna R.
AU  - Ristić, Zoran
AU  - Srivastava, A.M.
AU  - Beers, W.W.
AU  - Dramićanin, Miroslav
AU  - Brik, Mikhail G.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11576
AB  - The importance of structural disorder of crystal lattice for the formation of the optical properties of impurity ions is studied by evaluating the optical properties of Cr3+ impurity ions in Mg1-xZnxAl2O4:Cr3+ (x = 0; 0.25; 0.50; 0.75; 1.0) spinel solid solutions. It is demonstrated that the gradual replacement of Zn by Mg, which transforms the normal spinel ZnAl2O4 into the inverse spinel MgAl2O4, leads to an enhancement of the Cr3+ red emission. In addition, the Cr3+ decay rate (inverse to the emitting excited state lifetime) increases linearly when Zn is gradually replaced by Mg. These observations are explained by the lifting of the parity selection rule due to the random distribution of the Zn and Mg cations in the second coordination sphere around the emitting ion, which lowers the local symmetry at the impurity ion site. The strategy of deliberately creating disorder in the crystalline lattice is a successful way of increasing brightness and decreasing the excited state lifetime of the impurity ions, which can be applied for improving emission properties of the phosphor materials used in solid state lighting.
T2  - Journal of Luminescence
T1  - Influence of composition on the emission properties of impurities in solids: Case study of Mg1-xZnxAl2O4:Cr3+ with the spinel structure
VL  - 264
SP  - 120190
DO  - 10.1016/j.jlumin.2023.120190
ER  - 

@article{
author = "Antić, Željka and Đorđević, Vesna R. and Ristić, Zoran and Srivastava, A.M. and Beers, W.W. and Dramićanin, Miroslav and Brik, Mikhail G.",
year = "2023",
abstract = "The importance of structural disorder of crystal lattice for the formation of the optical properties of impurity ions is studied by evaluating the optical properties of Cr3+ impurity ions in Mg1-xZnxAl2O4:Cr3+ (x = 0; 0.25; 0.50; 0.75; 1.0) spinel solid solutions. It is demonstrated that the gradual replacement of Zn by Mg, which transforms the normal spinel ZnAl2O4 into the inverse spinel MgAl2O4, leads to an enhancement of the Cr3+ red emission. In addition, the Cr3+ decay rate (inverse to the emitting excited state lifetime) increases linearly when Zn is gradually replaced by Mg. These observations are explained by the lifting of the parity selection rule due to the random distribution of the Zn and Mg cations in the second coordination sphere around the emitting ion, which lowers the local symmetry at the impurity ion site. The strategy of deliberately creating disorder in the crystalline lattice is a successful way of increasing brightness and decreasing the excited state lifetime of the impurity ions, which can be applied for improving emission properties of the phosphor materials used in solid state lighting.",
journal = "Journal of Luminescence",
title = "Influence of composition on the emission properties of impurities in solids: Case study of Mg1-xZnxAl2O4:Cr3+ with the spinel structure",
volume = "264",
pages = "120190",
doi = "10.1016/j.jlumin.2023.120190"
}

Antić, Ž., Đorđević, V. R., Ristić, Z., Srivastava, A.M., Beers, W.W., Dramićanin, M.,& Brik, M. G.. (2023). Influence of composition on the emission properties of impurities in solids: Case study of Mg1-xZnxAl2O4:Cr3+ with the spinel structure. in Journal of Luminescence, 264, 120190.
https://doi.org/10.1016/j.jlumin.2023.120190

Antić Ž, Đorđević VR, Ristić Z, Srivastava A, Beers W, Dramićanin M, Brik MG. Influence of composition on the emission properties of impurities in solids: Case study of Mg1-xZnxAl2O4:Cr3+ with the spinel structure. in Journal of Luminescence. 2023;264:120190.
doi:10.1016/j.jlumin.2023.120190 .

Antić, Željka, Đorđević, Vesna R., Ristić, Zoran, Srivastava, A.M., Beers, W.W., Dramićanin, Miroslav, Brik, Mikhail G., "Influence of composition on the emission properties of impurities in solids: Case study of Mg1-xZnxAl2O4:Cr3+ with the spinel structure" in Journal of Luminescence, 264 (2023):120190,
https://doi.org/10.1016/j.jlumin.2023.120190 . .

TY  - JOUR
AU  - Nazarov, Michael V.
AU  - Spassky, Dmitry A.
AU  - Brik, Mikhail G.
AU  - Tsukerblat, Boris S.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11586
AB  - In this paper we report the luminescence properties of nanosized undoped and Eu2+ (1%) doped SrAl2O4 phosphors. The samples were prepared by combustion method at 600 ◦C followed by annealing of the resultant combustion ash at 1000 ◦C in a reductive (Ar + H2) atmosphere. Photo luminescence (PL) and cathodoluminescence (CL) analyses were applied to characterize the phosphors. The qualitative energy level scheme of doped crystal SrAl2O4:Eu2+ and nature of defects in undoped phosphor is proposed and discussed. Within a simplified model of a single vibration and linear vibronic coupling the shape-function of the vibrationally assisted band (Pekarian) is analyzed with the emphasis on the vibrational structure. We propose an approximate approach to pass from the discrete Pekarian distribution to the structureless crystal field spectra taking into account phonon dispersion. This approach is expected to be useful for the description of the shape of the bands when the electronic levels are close to the conduction band of the host crystal.
T2  - Optical Materials
T1  - About the nature of luminescent bands in undoped and Eu2+ doped SrAl2O4 phosphors
VL  - 145
SP  - 114377
DO  - 10.1016/j.optmat.2023.114377
ER  - 

@article{
author = "Nazarov, Michael V. and Spassky, Dmitry A. and Brik, Mikhail G. and Tsukerblat, Boris S.",
year = "2023",
abstract = "In this paper we report the luminescence properties of nanosized undoped and Eu2+ (1%) doped SrAl2O4 phosphors. The samples were prepared by combustion method at 600 ◦C followed by annealing of the resultant combustion ash at 1000 ◦C in a reductive (Ar + H2) atmosphere. Photo luminescence (PL) and cathodoluminescence (CL) analyses were applied to characterize the phosphors. The qualitative energy level scheme of doped crystal SrAl2O4:Eu2+ and nature of defects in undoped phosphor is proposed and discussed. Within a simplified model of a single vibration and linear vibronic coupling the shape-function of the vibrationally assisted band (Pekarian) is analyzed with the emphasis on the vibrational structure. We propose an approximate approach to pass from the discrete Pekarian distribution to the structureless crystal field spectra taking into account phonon dispersion. This approach is expected to be useful for the description of the shape of the bands when the electronic levels are close to the conduction band of the host crystal.",
journal = "Optical Materials",
title = "About the nature of luminescent bands in undoped and Eu2+ doped SrAl2O4 phosphors",
volume = "145",
pages = "114377",
doi = "10.1016/j.optmat.2023.114377"
}

Nazarov, M. V., Spassky, D. A., Brik, M. G.,& Tsukerblat, B. S.. (2023). About the nature of luminescent bands in undoped and Eu2+ doped SrAl2O4 phosphors. in Optical Materials, 145, 114377.
https://doi.org/10.1016/j.optmat.2023.114377

Nazarov MV, Spassky DA, Brik MG, Tsukerblat BS. About the nature of luminescent bands in undoped and Eu2+ doped SrAl2O4 phosphors. in Optical Materials. 2023;145:114377.
doi:10.1016/j.optmat.2023.114377 .

Nazarov, Michael V., Spassky, Dmitry A., Brik, Mikhail G., Tsukerblat, Boris S., "About the nature of luminescent bands in undoped and Eu2+ doped SrAl2O4 phosphors" in Optical Materials, 145 (2023):114377,
https://doi.org/10.1016/j.optmat.2023.114377 . .

TY  - JOUR
AU  - Buryi, M.
AU  - Neykova, N.
AU  - Brik, Mikhail G.
AU  - Wang, Yu-Min
AU  - Remeš, Z.
AU  - Ridzonova, K.
AU  - Babin, V.
AU  - Davydova, M.
AU  - Drahokoupil, J.
AU  - Chertopalov, S.
AU  - Landová, L.
AU  - Pop-Georgievski, O.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11721
AB  - Molybdenum doped ZnO was hydrothermally grown as the arrays of nanorods deposited onto the fused silica glass substrate. The molybdenum doping level varied from 1 to 30 %. The influence of Mo on the electronic and crystalline structure as well as luminescence and defects in the ZnO nanorods is under study of the bundle of experimental techniques complemented with density functional theory calculations. The tendency of Mo to create energy states within the bandgap of ZnO and their influence on the energy levels of native defects as well as excitons were proven by the synergy of experiment and theory. The improvement of the timing characteristics of the exciton- and zinc vacancy-related emission bands upon Mo doping (1–10 %) was observed. This paves the way for the defect engineering strategy in the search of effective and ultrafast scintillator with the improved light yield as well as compared to other materials. The new concept is based on the combination of the exciton and the defect emission. It is expected to have the potential of application in the detection of gamma rays implemented in time-of-flight positron emission tomography (TOFPET). The 20 and 30 % Mo doping levels resulted in the zinc molybdates creation strongly outnumbering ZnO nanorods.
T2  - Optical Materials
T1  - Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator
VL  - 145
SP  - 114445
DO  - 10.1016/j.optmat.2023.114445
ER  - 

@article{
author = "Buryi, M. and Neykova, N. and Brik, Mikhail G. and Wang, Yu-Min and Remeš, Z. and Ridzonova, K. and Babin, V. and Davydova, M. and Drahokoupil, J. and Chertopalov, S. and Landová, L. and Pop-Georgievski, O.",
year = "2023",
abstract = "Molybdenum doped ZnO was hydrothermally grown as the arrays of nanorods deposited onto the fused silica glass substrate. The molybdenum doping level varied from 1 to 30 %. The influence of Mo on the electronic and crystalline structure as well as luminescence and defects in the ZnO nanorods is under study of the bundle of experimental techniques complemented with density functional theory calculations. The tendency of Mo to create energy states within the bandgap of ZnO and their influence on the energy levels of native defects as well as excitons were proven by the synergy of experiment and theory. The improvement of the timing characteristics of the exciton- and zinc vacancy-related emission bands upon Mo doping (1–10 %) was observed. This paves the way for the defect engineering strategy in the search of effective and ultrafast scintillator with the improved light yield as well as compared to other materials. The new concept is based on the combination of the exciton and the defect emission. It is expected to have the potential of application in the detection of gamma rays implemented in time-of-flight positron emission tomography (TOFPET). The 20 and 30 % Mo doping levels resulted in the zinc molybdates creation strongly outnumbering ZnO nanorods.",
journal = "Optical Materials",
title = "Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator",
volume = "145",
pages = "114445",
doi = "10.1016/j.optmat.2023.114445"
}

Buryi, M., Neykova, N., Brik, M. G., Wang, Y., Remeš, Z., Ridzonova, K., Babin, V., Davydova, M., Drahokoupil, J., Chertopalov, S., Landová, L.,& Pop-Georgievski, O.. (2023). Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator. in Optical Materials, 145, 114445.
https://doi.org/10.1016/j.optmat.2023.114445

Buryi M, Neykova N, Brik MG, Wang Y, Remeš Z, Ridzonova K, Babin V, Davydova M, Drahokoupil J, Chertopalov S, Landová L, Pop-Georgievski O. Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator. in Optical Materials. 2023;145:114445.
doi:10.1016/j.optmat.2023.114445 .

Buryi, M., Neykova, N., Brik, Mikhail G., Wang, Yu-Min, Remeš, Z., Ridzonova, K., Babin, V., Davydova, M., Drahokoupil, J., Chertopalov, S., Landová, L., Pop-Georgievski, O., "Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator" in Optical Materials, 145 (2023):114445,
https://doi.org/10.1016/j.optmat.2023.114445 . .

TY  - JOUR
AU  - Rudysh, Myron Ya.
AU  - Fedorchuk, Anatolii O.
AU  - Brik, Mikhail G.
AU  - Grechenkov, Jurij
AU  - Bocharov, Dmitry
AU  - Piskunov, Sergei
AU  - Popov, Anatoli I.
AU  - Piasecki, Michal
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12044
AB  - The aim of this study is to comprehensively examine the structural composition and
properties of the AgAlS2 crystal during its high-pressure phase. This analysis delves into the second
coordination environment of the crystal structure and elucidates the distinct transformations it
undergoes during the phase transition. The band energy structure was calculated, and the origin
of electronic levels was clarified. It is shown that the crystal becomes non-stratified during the
phase transition. This study also determined the values of the crystal’s carrier effective masses,
underscoring its spatial anisotropy. It was found that the calculated optical functions are similar to
the crystal in the chalcopyrite structure, and their differences are shown. Further, this study involved
the calculation of the crystal’s phonon spectrum, revealing the spectrum’s transformation during the
phase transition. The vibrational frequencies were also obtained, with a symmetrical classification of
vibrational modes. Finally, this study derived the infrared and Raman spectra of the AgAlS2 crystal,
thereby providing a comprehensive picture of the crystal during its high-pressure phase.
T2  - Materials
T1  - Electronic, Optical, and Vibrational Properties of an AgAlS2 Crystal in a High-Pressure Phase
VL  - 16
IS  - 21
SP  - 7017
DO  - 10.3390/ma16217017
ER  - 

@article{
author = "Rudysh, Myron Ya. and Fedorchuk, Anatolii O. and Brik, Mikhail G. and Grechenkov, Jurij and Bocharov, Dmitry and Piskunov, Sergei and Popov, Anatoli I. and Piasecki, Michal",
year = "2023",
abstract = "The aim of this study is to comprehensively examine the structural composition and
properties of the AgAlS2 crystal during its high-pressure phase. This analysis delves into the second
coordination environment of the crystal structure and elucidates the distinct transformations it
undergoes during the phase transition. The band energy structure was calculated, and the origin
of electronic levels was clarified. It is shown that the crystal becomes non-stratified during the
phase transition. This study also determined the values of the crystal’s carrier effective masses,
underscoring its spatial anisotropy. It was found that the calculated optical functions are similar to
the crystal in the chalcopyrite structure, and their differences are shown. Further, this study involved
the calculation of the crystal’s phonon spectrum, revealing the spectrum’s transformation during the
phase transition. The vibrational frequencies were also obtained, with a symmetrical classification of
vibrational modes. Finally, this study derived the infrared and Raman spectra of the AgAlS2 crystal,
thereby providing a comprehensive picture of the crystal during its high-pressure phase.",
journal = "Materials",
title = "Electronic, Optical, and Vibrational Properties of an AgAlS2 Crystal in a High-Pressure Phase",
volume = "16",
number = "21",
pages = "7017",
doi = "10.3390/ma16217017"
}

Rudysh, M. Ya., Fedorchuk, A. O., Brik, M. G., Grechenkov, J., Bocharov, D., Piskunov, S., Popov, A. I.,& Piasecki, M.. (2023). Electronic, Optical, and Vibrational Properties of an AgAlS2 Crystal in a High-Pressure Phase. in Materials, 16(21), 7017.
https://doi.org/10.3390/ma16217017

Rudysh MY, Fedorchuk AO, Brik MG, Grechenkov J, Bocharov D, Piskunov S, Popov AI, Piasecki M. Electronic, Optical, and Vibrational Properties of an AgAlS2 Crystal in a High-Pressure Phase. in Materials. 2023;16(21):7017.
doi:10.3390/ma16217017 .

Rudysh, Myron Ya., Fedorchuk, Anatolii O., Brik, Mikhail G., Grechenkov, Jurij, Bocharov, Dmitry, Piskunov, Sergei, Popov, Anatoli I., Piasecki, Michal, "Electronic, Optical, and Vibrational Properties of an AgAlS2 Crystal in a High-Pressure Phase" in Materials, 16, no. 21 (2023):7017,
https://doi.org/10.3390/ma16217017 . .

TY  - JOUR
AU  - Srivastava, Alok M.
AU  - Brik, Mikhail G.
AU  - Beers, William W.
AU  - Cohen, William E.
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10601
AB  - The relationship between the Stokes shift of Bi3+ emission and the volume of the unit-cell in two series of orthorhombic perovskites, LnB 3+O3 (Ln = La, Gd, Y; B 3+ = Al, In, Ga) and AB 4+O3 (A = Ca, Sr; B 4+ = Zr, Sn) is explored. The Stokes shift increases linearly with increasing cell volume. This is explained qualitatively by the lattice chemical pressure acting on the Bi3+ ion. The degree of Bi3+ ion off-centering displacement, which is due to the stereochemical activity of the lone-pair electrons (6 s2), is controlled by the chemical pressure. A small cell suppresses the off-centering displacement to produce a small Stokes shift of emission by limiting the excited state structural distortion. In large cell, the off-centering displacement is more easily accommodated. The elimination of ground state distortion in the excited state gives larger Stokes shift of emission. These qualitative arguments are supplemented by recent first-principles calculations on Bi3+ luminescence in these perovskites. The Bi3+ luminescence in SrZrO3, previously assigned to emission from the D-state, is now assigned to the localized 3P0,1 → 1S0 transition. The energy of the 1S0 → 3P1 transition is correlated with the covalence of the BO6/2 perovskite framework. Discussion on the effective ionic radius of the Bi3+ ion in these perovskites is presented.
T2  - ECS Journal of Solid State Science and Technology
T1  - Chemical Pressure Effects on the Stokes Shift of Bi3+ Luminescence in Orthorhombic Perovskites
VL  - 11
IS  - 9
SP  - 096003
DO  - 10.1149/2162-8777/ac915b
ER  - 

@article{
author = "Srivastava, Alok M. and Brik, Mikhail G. and Beers, William W. and Cohen, William E.",
year = "2022",
abstract = "The relationship between the Stokes shift of Bi3+ emission and the volume of the unit-cell in two series of orthorhombic perovskites, LnB 3+O3 (Ln = La, Gd, Y; B 3+ = Al, In, Ga) and AB 4+O3 (A = Ca, Sr; B 4+ = Zr, Sn) is explored. The Stokes shift increases linearly with increasing cell volume. This is explained qualitatively by the lattice chemical pressure acting on the Bi3+ ion. The degree of Bi3+ ion off-centering displacement, which is due to the stereochemical activity of the lone-pair electrons (6 s2), is controlled by the chemical pressure. A small cell suppresses the off-centering displacement to produce a small Stokes shift of emission by limiting the excited state structural distortion. In large cell, the off-centering displacement is more easily accommodated. The elimination of ground state distortion in the excited state gives larger Stokes shift of emission. These qualitative arguments are supplemented by recent first-principles calculations on Bi3+ luminescence in these perovskites. The Bi3+ luminescence in SrZrO3, previously assigned to emission from the D-state, is now assigned to the localized 3P0,1 → 1S0 transition. The energy of the 1S0 → 3P1 transition is correlated with the covalence of the BO6/2 perovskite framework. Discussion on the effective ionic radius of the Bi3+ ion in these perovskites is presented.",
journal = "ECS Journal of Solid State Science and Technology",
title = "Chemical Pressure Effects on the Stokes Shift of Bi3+ Luminescence in Orthorhombic Perovskites",
volume = "11",
number = "9",
pages = "096003",
doi = "10.1149/2162-8777/ac915b"
}

Srivastava, A. M., Brik, M. G., Beers, W. W.,& Cohen, W. E.. (2022). Chemical Pressure Effects on the Stokes Shift of Bi3+ Luminescence in Orthorhombic Perovskites. in ECS Journal of Solid State Science and Technology, 11(9), 096003.
https://doi.org/10.1149/2162-8777/ac915b

Srivastava AM, Brik MG, Beers WW, Cohen WE. Chemical Pressure Effects on the Stokes Shift of Bi3+ Luminescence in Orthorhombic Perovskites. in ECS Journal of Solid State Science and Technology. 2022;11(9):096003.
doi:10.1149/2162-8777/ac915b .

Srivastava, Alok M., Brik, Mikhail G., Beers, William W., Cohen, William E., "Chemical Pressure Effects on the Stokes Shift of Bi3+ Luminescence in Orthorhombic Perovskites" in ECS Journal of Solid State Science and Technology, 11, no. 9 (2022):096003,
https://doi.org/10.1149/2162-8777/ac915b . .