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  - Umar, Zafari
AU  - Kurboniyon, Mekhrdod S.
AU  - Khyzhun, Oleg
AU  - Yamamoto, Tomoyuki
AU  - Ma, Chong-Geng
AU  - Brik, Mikhail G.
AU  - Piasecki, Michal
PY  - 2024
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11826
AB  - We report on the results of the first principles calculations based on density functional theory (DFT) of the electronic structure and mechanical properties of K2LiAlF6, both non-doped and doped with Cr3+ ions. The densities of states of K2LiAlF6 and the K2LiAlF6:Cr3+ phosphor as well as the crystal-field strength 10Dq, the Cr3+ 2E→4A2 emission energy, elastic constants, bulk and shear moduli, sound velocities and Debye temperature as functions of hydrostatic pressure ranging from 0 up to 40 GPa were calculated. The present DFT calculations indicate that, the band gap of non-doped K2LiAlF6 increases quadratically with increasing pressure. Further, the crystal field strength 10Dq and the 2E→4A2 emission energy, the Debye temperature, sound velocities and shear moduli of Cr-doped K2LiAlF6 increase with increasing pressure, while the 2E→4A2 emission energy becomes red-shifted, which indicates potential applicability of the studied system for pressure sensing. Such calculations for the title system were performed for the first time; the obtained results provide a firm basis for a deeper understanding of physical properties of both neat and doped functional materials.
T2  - Journal of Luminescence
T1  - First-principles calculations of the electronic structure and mechanical properties of non-doped and Cr3+-Doped K2LiAlF6 under pressure
VL  - 266
SP  - 120278
DO  - 10.1016/j.jlumin.2023.120278
ER  - 

@article{
author = "Umar, Zafari and Kurboniyon, Mekhrdod S. and Khyzhun, Oleg and Yamamoto, Tomoyuki and Ma, Chong-Geng and Brik, Mikhail G. and Piasecki, Michal",
year = "2024",
abstract = "We report on the results of the first principles calculations based on density functional theory (DFT) of the electronic structure and mechanical properties of K2LiAlF6, both non-doped and doped with Cr3+ ions. The densities of states of K2LiAlF6 and the K2LiAlF6:Cr3+ phosphor as well as the crystal-field strength 10Dq, the Cr3+ 2E→4A2 emission energy, elastic constants, bulk and shear moduli, sound velocities and Debye temperature as functions of hydrostatic pressure ranging from 0 up to 40 GPa were calculated. The present DFT calculations indicate that, the band gap of non-doped K2LiAlF6 increases quadratically with increasing pressure. Further, the crystal field strength 10Dq and the 2E→4A2 emission energy, the Debye temperature, sound velocities and shear moduli of Cr-doped K2LiAlF6 increase with increasing pressure, while the 2E→4A2 emission energy becomes red-shifted, which indicates potential applicability of the studied system for pressure sensing. Such calculations for the title system were performed for the first time; the obtained results provide a firm basis for a deeper understanding of physical properties of both neat and doped functional materials.",
journal = "Journal of Luminescence",
title = "First-principles calculations of the electronic structure and mechanical properties of non-doped and Cr3+-Doped K2LiAlF6 under pressure",
volume = "266",
pages = "120278",
doi = "10.1016/j.jlumin.2023.120278"
}

Umar, Z., Kurboniyon, M. S., Khyzhun, O., Yamamoto, T., Ma, C., Brik, M. G.,& Piasecki, M.. (2024). First-principles calculations of the electronic structure and mechanical properties of non-doped and Cr3+-Doped K2LiAlF6 under pressure. in Journal of Luminescence, 266, 120278.
https://doi.org/10.1016/j.jlumin.2023.120278

Umar Z, Kurboniyon MS, Khyzhun O, Yamamoto T, Ma C, Brik MG, Piasecki M. First-principles calculations of the electronic structure and mechanical properties of non-doped and Cr3+-Doped K2LiAlF6 under pressure. in Journal of Luminescence. 2024;266:120278.
doi:10.1016/j.jlumin.2023.120278 .

Umar, Zafari, Kurboniyon, Mekhrdod S., Khyzhun, Oleg, Yamamoto, Tomoyuki, Ma, Chong-Geng, Brik, Mikhail G., Piasecki, Michal, "First-principles calculations of the electronic structure and mechanical properties of non-doped and Cr3+-Doped K2LiAlF6 under pressure" in Journal of Luminescence, 266 (2024):120278,
https://doi.org/10.1016/j.jlumin.2023.120278 . .

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 . .