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  - Zou, Wei
AU  - Lou, Bibo
AU  - Kurboniyon, Mekhrdod S.
AU  - Buryi, Maksym
AU  - Rahimi, Farhod
AU  - Srivastava, Alok M.
AU  - Brik, Mikhail G.
AU  - Wang, Jing
AU  - Ma, Chonggeng
PY  - 2024
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/13187
AB  - In this study, we conducted an extensive investigation into broadband near-infrared luminescence of Cr3+-doped Ca3Y2Ge3O12 garnet, employing first-principles calculations within the density functional theory framework. Our initial focus involved determining the site occupancy of Cr3+ activator ions, which revealed a pronounced preference for the Y3+ sites over the Ca2+ and Ge4+ sites, as evidenced by the formation energy calculations. Subsequently, the geometric structures of the excited states 2E and 4T2, along with their optical transition energies relative to the ground state 4A2 in Ca3Y2Ge3O12:Cr3+, were successfully modeled using the ΔSCF method. Calculation convergence challenges were effectively addressed through the proposed fractional particle occupancy schemes. The constructed host-referred binding energy diagram provided a clear description of the luminescence kinetics process in the garnet, which explained the high quantum efficiency of emission. Furthermore, the accurate prediction of thermal excitation energy yielded insights into the thermal stability of the compound, as illustrated in the calculated configuration coordinate diagram. More importantly, all calculated data were consistently aligned with the experimental results. This research not only advances our understanding of the intricate interplay between geometric and electronic structures, optical properties, and thermal behavior in Cr3+-doped garnets but also lays the groundwork for future breakthroughs in the high-throughput design and optimization of luminescent performance and thermal stability in Cr3+-doped phosphors.
T2  - Materials
T1  - Unraveling Broadband Near-Infrared Luminescence in Cr3+-Doped Ca3Y2Ge3O12 Garnets: Insights from First-Principles Analysis
VL  - 17
IS  - 7
SP  - 1709
DO  - 10.3390/ma17071709
ER  - 

@article{
author = "Zou, Wei and Lou, Bibo and Kurboniyon, Mekhrdod S. and Buryi, Maksym and Rahimi, Farhod and Srivastava, Alok M. and Brik, Mikhail G. and Wang, Jing and Ma, Chonggeng",
year = "2024",
abstract = "In this study, we conducted an extensive investigation into broadband near-infrared luminescence of Cr3+-doped Ca3Y2Ge3O12 garnet, employing first-principles calculations within the density functional theory framework. Our initial focus involved determining the site occupancy of Cr3+ activator ions, which revealed a pronounced preference for the Y3+ sites over the Ca2+ and Ge4+ sites, as evidenced by the formation energy calculations. Subsequently, the geometric structures of the excited states 2E and 4T2, along with their optical transition energies relative to the ground state 4A2 in Ca3Y2Ge3O12:Cr3+, were successfully modeled using the ΔSCF method. Calculation convergence challenges were effectively addressed through the proposed fractional particle occupancy schemes. The constructed host-referred binding energy diagram provided a clear description of the luminescence kinetics process in the garnet, which explained the high quantum efficiency of emission. Furthermore, the accurate prediction of thermal excitation energy yielded insights into the thermal stability of the compound, as illustrated in the calculated configuration coordinate diagram. More importantly, all calculated data were consistently aligned with the experimental results. This research not only advances our understanding of the intricate interplay between geometric and electronic structures, optical properties, and thermal behavior in Cr3+-doped garnets but also lays the groundwork for future breakthroughs in the high-throughput design and optimization of luminescent performance and thermal stability in Cr3+-doped phosphors.",
journal = "Materials",
title = "Unraveling Broadband Near-Infrared Luminescence in Cr3+-Doped Ca3Y2Ge3O12 Garnets: Insights from First-Principles Analysis",
volume = "17",
number = "7",
pages = "1709",
doi = "10.3390/ma17071709"
}

Zou, W., Lou, B., Kurboniyon, M. S., Buryi, M., Rahimi, F., Srivastava, A. M., Brik, M. G., Wang, J.,& Ma, C.. (2024). Unraveling Broadband Near-Infrared Luminescence in Cr3+-Doped Ca3Y2Ge3O12 Garnets: Insights from First-Principles Analysis. in Materials, 17(7), 1709.
https://doi.org/10.3390/ma17071709

Zou W, Lou B, Kurboniyon MS, Buryi M, Rahimi F, Srivastava AM, Brik MG, Wang J, Ma C. Unraveling Broadband Near-Infrared Luminescence in Cr3+-Doped Ca3Y2Ge3O12 Garnets: Insights from First-Principles Analysis. in Materials. 2024;17(7):1709.
doi:10.3390/ma17071709 .

Zou, Wei, Lou, Bibo, Kurboniyon, Mekhrdod S., Buryi, Maksym, Rahimi, Farhod, Srivastava, Alok M., Brik, Mikhail G., Wang, Jing, Ma, Chonggeng, "Unraveling Broadband Near-Infrared Luminescence in Cr3+-Doped Ca3Y2Ge3O12 Garnets: Insights from First-Principles Analysis" in Materials, 17, no. 7 (2024):1709,
https://doi.org/10.3390/ma17071709 . .

TY  - JOUR
AU  - Srivastava, Alok M
AU  - Suchocki, Andrzej
AU  - Bulyk, Lev-Ivan
AU  - Zhydachevskyy, Yaroslav
AU  - Brik, Mikhail G.
AU  - Beers, William W
AU  - Cohen, Willian E
PY  - 2024
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/13124
AB  - We have measured the excitation and emission spectra, and lifetime for Fe3+ in the Ca8Mg(SiO4)4Cl2 compound. The spectroscopic data of the ferric ion (Fe3+) is interpreted within the framework of the Tanabe-Sugano crystal field theory for ions with the d5 electronic configuration. Quantitative evaluation of the Racah parameters B and C and the crystal field parameter (10 Dq) is provided. The emission and excitation data are consistent for Fe3+ in a tetrahedral-site occupancy. The red emission is assigned to the 4T1 (4G)→6A1 (6S) crystal field transition. The remarkable feature of the luminescence is the positioning of the emission band; it is centered at 623 nm with a Full Width at Half Maximum of 51 nm. To the best of our knowledge this is one of the highest energy emission for the tetrahedral-site Fe3+ ion. The practical implication of this spectral power distribution is discussed. The temperature dependency of the luminescence lifetime and emission intensity are reported.
T2  - Optical Materials
T1  - Narrowband red luminescence of tetrahedral-site Fe3+ In Ca8Mg(SiO4)4Cl2
VL  - 150
SP  - 115290
DO  - 10.1016/j.optmat.2024.115290
ER  - 

@article{
author = "Srivastava, Alok M and Suchocki, Andrzej and Bulyk, Lev-Ivan and Zhydachevskyy, Yaroslav and Brik, Mikhail G. and Beers, William W and Cohen, Willian E",
year = "2024",
abstract = "We have measured the excitation and emission spectra, and lifetime for Fe3+ in the Ca8Mg(SiO4)4Cl2 compound. The spectroscopic data of the ferric ion (Fe3+) is interpreted within the framework of the Tanabe-Sugano crystal field theory for ions with the d5 electronic configuration. Quantitative evaluation of the Racah parameters B and C and the crystal field parameter (10 Dq) is provided. The emission and excitation data are consistent for Fe3+ in a tetrahedral-site occupancy. The red emission is assigned to the 4T1 (4G)→6A1 (6S) crystal field transition. The remarkable feature of the luminescence is the positioning of the emission band; it is centered at 623 nm with a Full Width at Half Maximum of 51 nm. To the best of our knowledge this is one of the highest energy emission for the tetrahedral-site Fe3+ ion. The practical implication of this spectral power distribution is discussed. The temperature dependency of the luminescence lifetime and emission intensity are reported.",
journal = "Optical Materials",
title = "Narrowband red luminescence of tetrahedral-site Fe3+ In Ca8Mg(SiO4)4Cl2",
volume = "150",
pages = "115290",
doi = "10.1016/j.optmat.2024.115290"
}

Srivastava, A. M., Suchocki, A., Bulyk, L., Zhydachevskyy, Y., Brik, M. G., Beers, W. W.,& Cohen, W. E.. (2024). Narrowband red luminescence of tetrahedral-site Fe3+ In Ca8Mg(SiO4)4Cl2. in Optical Materials, 150, 115290.
https://doi.org/10.1016/j.optmat.2024.115290

Srivastava AM, Suchocki A, Bulyk L, Zhydachevskyy Y, Brik MG, Beers WW, Cohen WE. Narrowband red luminescence of tetrahedral-site Fe3+ In Ca8Mg(SiO4)4Cl2. in Optical Materials. 2024;150:115290.
doi:10.1016/j.optmat.2024.115290 .

Srivastava, Alok M, Suchocki, Andrzej, Bulyk, Lev-Ivan, Zhydachevskyy, Yaroslav, Brik, Mikhail G., Beers, William W, Cohen, Willian E, "Narrowband red luminescence of tetrahedral-site Fe3+ In Ca8Mg(SiO4)4Cl2" in Optical Materials, 150 (2024):115290,
https://doi.org/10.1016/j.optmat.2024.115290 . .

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 . .