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  - Kurboniyon, Mekhrdod S.
AU  - Lou, Bibo
AU  - Zafari, Umar
AU  - Rahimi, Farhod
AU  - Srivastava, Alok M.
AU  - Yamamoto, Tomoyuki
AU  - Brik, Mikhail G.
AU  - Ma, Chong-Geng
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11381
AB  - In this study, we present the results of first-principles calculations conducted within the density functional theory to investigate the geometric and electronic structures of the ground 4 A2 and excited 2 E and 4 T2 states, as well as the optical transition energies between these states, in the prototype system of K2SiF6:Mn4+. To achieve this, we employed a comprehensive evaluation of the five representative exchange-correlation functionals, enabling the development of a state-of-art calculation scheme that effectively describes the geometric and electronic structures of the excited 2 E and 4 T2 states. The calculated excitation, emission and zero-phonon line energies of the optical transitions between the ground 4 A2 state and the excited 2 E and 4 T2 states demonstrate a better agreement with experimental results. However, we observed that the conventional and widely-used approach based on the analysis of the electronic density of states diagrams derived from the ground state calculations failed to accurately evaluate the vertical optical transition energies from the 4 A2 ground state to the excited 2 E and 4 T2 states when compared to experimental data. The calculation technique developed in this study holds the potential for widespread application to other combinations of host materials and impurity ion, which is of great importance for future developments in the field of optical materials.
T2  - Journal of Luminescence
T1  - First-principles study of geometric and electronic structures, and optical transition energies of Mn4+ impurity ions: K2SiF6 as a prototype
VL  - 263
SP  - 120103
DO  - 10.1016/j.jlumin.2023.120103
ER  - 

@article{
author = "Kurboniyon, Mekhrdod S. and Lou, Bibo and Zafari, Umar and Rahimi, Farhod and Srivastava, Alok M. and Yamamoto, Tomoyuki and Brik, Mikhail G. and Ma, Chong-Geng",
year = "2023",
abstract = "In this study, we present the results of first-principles calculations conducted within the density functional theory to investigate the geometric and electronic structures of the ground 4 A2 and excited 2 E and 4 T2 states, as well as the optical transition energies between these states, in the prototype system of K2SiF6:Mn4+. To achieve this, we employed a comprehensive evaluation of the five representative exchange-correlation functionals, enabling the development of a state-of-art calculation scheme that effectively describes the geometric and electronic structures of the excited 2 E and 4 T2 states. The calculated excitation, emission and zero-phonon line energies of the optical transitions between the ground 4 A2 state and the excited 2 E and 4 T2 states demonstrate a better agreement with experimental results. However, we observed that the conventional and widely-used approach based on the analysis of the electronic density of states diagrams derived from the ground state calculations failed to accurately evaluate the vertical optical transition energies from the 4 A2 ground state to the excited 2 E and 4 T2 states when compared to experimental data. The calculation technique developed in this study holds the potential for widespread application to other combinations of host materials and impurity ion, which is of great importance for future developments in the field of optical materials.",
journal = "Journal of Luminescence",
title = "First-principles study of geometric and electronic structures, and optical transition energies of Mn4+ impurity ions: K2SiF6 as a prototype",
volume = "263",
pages = "120103",
doi = "10.1016/j.jlumin.2023.120103"
}

Kurboniyon, M. S., Lou, B., Zafari, U., Rahimi, F., Srivastava, A. M., Yamamoto, T., Brik, M. G.,& Ma, C.. (2023). First-principles study of geometric and electronic structures, and optical transition energies of Mn4+ impurity ions: K2SiF6 as a prototype. in Journal of Luminescence, 263, 120103.
https://doi.org/10.1016/j.jlumin.2023.120103

Kurboniyon MS, Lou B, Zafari U, Rahimi F, Srivastava AM, Yamamoto T, Brik MG, Ma C. First-principles study of geometric and electronic structures, and optical transition energies of Mn4+ impurity ions: K2SiF6 as a prototype. in Journal of Luminescence. 2023;263:120103.
doi:10.1016/j.jlumin.2023.120103 .

Kurboniyon, Mekhrdod S., Lou, Bibo, Zafari, Umar, Rahimi, Farhod, Srivastava, Alok M., Yamamoto, Tomoyuki, Brik, Mikhail G., Ma, Chong-Geng, "First-principles study of geometric and electronic structures, and optical transition energies of Mn4+ impurity ions: K2SiF6 as a prototype" in Journal of Luminescence, 263 (2023):120103,
https://doi.org/10.1016/j.jlumin.2023.120103 . .