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  - 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  - 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  - Srivastava, Alok M.
AU  - Brik, Mikhail
AU  - Beers, William W.
AU  - Lou, B.
AU  - Ma, C.-G.
AU  - Piasecki, Michal
AU  - Cohen, William E.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11170
AB  - A comparative study of Eu3+ ion luminescence in YXO4 (X=P, As, V) with the tetragonal zircon structure is conducted in relation to the intensity of the hypersensitivity 5D0 → 7F2 Δ J = 2 transition. Both the asymmetry ratio, R = I 5 D 0 − 7 F 2 I 5 D 0 − 7 F 1 , and the Judd-Ofelt Ω2 intensity parameter increases in the order YPO4 < YAsO4 < YVO4. This correlation is interpreted qualitatively in terms of the covalency and polarizability of (XO4)3−, which increases in the order (PO4)3− < (AsO4)3− < (VO4)3−. The trend is supported by the results of electronic band structure calculations of the three compounds which establish the strength of hybridization between the X cation and the oxygen 2p states. The electronic structure of YAsO4 is calculated to probe the covalence of As-O bonding. The increasing oscillator strength of the Eu3+5D0 → 7F2 transition in going from YPO4 to YAsO4 to YVO4 is consistent with the expectation of ligand dipolar polarization model for hypersensitivity which states that the oscillator strength of the 5D0 → 7F2 transition is proportional to the square of the ligand dipolar polarizability. The connection between the mechanism of hypersensitivity and second harmonic generation (SHG) is presented. © 2023 The Electrochemical Society (“ECS”). Published on behalf of ECS by IOP Publishing Limited.
T2  - ECS Journal of Solid State Science and Technology
T1  - Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V)
VL  - 12
IS  - 6
SP  - 066001
DO  - 10.1149/2162-8777/acd80f
ER  - 

@article{
author = "Srivastava, Alok M. and Brik, Mikhail and Beers, William W. and Lou, B. and Ma, C.-G. and Piasecki, Michal and Cohen, William E.",
year = "2023",
abstract = "A comparative study of Eu3+ ion luminescence in YXO4 (X=P, As, V) with the tetragonal zircon structure is conducted in relation to the intensity of the hypersensitivity 5D0 → 7F2 Δ J = 2 transition. Both the asymmetry ratio, R = I 5 D 0 − 7 F 2 I 5 D 0 − 7 F 1 , and the Judd-Ofelt Ω2 intensity parameter increases in the order YPO4 < YAsO4 < YVO4. This correlation is interpreted qualitatively in terms of the covalency and polarizability of (XO4)3−, which increases in the order (PO4)3− < (AsO4)3− < (VO4)3−. The trend is supported by the results of electronic band structure calculations of the three compounds which establish the strength of hybridization between the X cation and the oxygen 2p states. The electronic structure of YAsO4 is calculated to probe the covalence of As-O bonding. The increasing oscillator strength of the Eu3+5D0 → 7F2 transition in going from YPO4 to YAsO4 to YVO4 is consistent with the expectation of ligand dipolar polarization model for hypersensitivity which states that the oscillator strength of the 5D0 → 7F2 transition is proportional to the square of the ligand dipolar polarizability. The connection between the mechanism of hypersensitivity and second harmonic generation (SHG) is presented. © 2023 The Electrochemical Society (“ECS”). Published on behalf of ECS by IOP Publishing Limited.",
journal = "ECS Journal of Solid State Science and Technology",
title = "Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V)",
volume = "12",
number = "6",
pages = "066001",
doi = "10.1149/2162-8777/acd80f"
}

Srivastava, A. M., Brik, M., Beers, W. W., Lou, B., Ma, C.-G., Piasecki, M.,& Cohen, W. E.. (2023). Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V). in ECS Journal of Solid State Science and Technology, 12(6), 066001.
https://doi.org/10.1149/2162-8777/acd80f

Srivastava AM, Brik M, Beers WW, Lou B, Ma C, Piasecki M, Cohen WE. Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V). in ECS Journal of Solid State Science and Technology. 2023;12(6):066001.
doi:10.1149/2162-8777/acd80f .

Srivastava, Alok M., Brik, Mikhail, Beers, William W., Lou, B., Ma, C.-G., Piasecki, Michal, Cohen, William E., "Orbital Hybridization and Hypersensitivity of Eu3+ in YXO4 (X=P, As, V)" in ECS Journal of Solid State Science and Technology, 12, no. 6 (2023):066001,
https://doi.org/10.1149/2162-8777/acd80f . .

TY  - JOUR
AU  - Andreici Etimie, E. L.
AU  - Avram, Nicolae M.
AU  - Brik, Mikhail G.
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10452
AB  - The normal spinels (Mg, Zn)Al2O4 doped with transition metal (TM) ions Cr3+/Co2+ are versatile materials with important electronic, optical and spectral properties. In addition to being used in many applications, they are excellent systems for testing some models and simulation features. The aim of this paper is to present, in the unified frame, the results on d-d transitions and ligand field parameters (LFPs) for the title systems, based on ab initio calculations, combining periodic density functional theory (DFT) supercell approach with ab initio (AI) multi -reference perturbation theory (MRPT) and multi-reference configuration interaction (MRCI) methods. These AI methods, based on complete active space self-consistent-field (CASSCF) reference, allow to calculate and investigate the energy levels of TM ions and the d-d transitions between them. From the AI results the B and C Racah parameters, the spin-orbit coupling (SOC) constant and the LFPs in the frame of the angular overlap model (AOM) were accurately extracted with ab initio ligand field theory (AILFT) protocol, all with subsequent comparison with the experimental data or existing theoretical results in the literature. The calculation technique presented in this paper serves as a predictive formalism for further studies of larger monomer clusters, for which experimental data is unreliable or unavailable.
T2  - Optical Materials: X
T1  - The d-d transitions and ligand field parameters for Cr3+/Co2+ doped (Mg, Zn)Al2O4: Multi-reference Ab initio investigations
VL  - 16
SP  - 100188
DO  - 10.1016/j.omx.2022.100188
ER  - 

@article{
author = "Andreici Etimie, E. L. and Avram, Nicolae M. and Brik, Mikhail G.",
year = "2022",
abstract = "The normal spinels (Mg, Zn)Al2O4 doped with transition metal (TM) ions Cr3+/Co2+ are versatile materials with important electronic, optical and spectral properties. In addition to being used in many applications, they are excellent systems for testing some models and simulation features. The aim of this paper is to present, in the unified frame, the results on d-d transitions and ligand field parameters (LFPs) for the title systems, based on ab initio calculations, combining periodic density functional theory (DFT) supercell approach with ab initio (AI) multi -reference perturbation theory (MRPT) and multi-reference configuration interaction (MRCI) methods. These AI methods, based on complete active space self-consistent-field (CASSCF) reference, allow to calculate and investigate the energy levels of TM ions and the d-d transitions between them. From the AI results the B and C Racah parameters, the spin-orbit coupling (SOC) constant and the LFPs in the frame of the angular overlap model (AOM) were accurately extracted with ab initio ligand field theory (AILFT) protocol, all with subsequent comparison with the experimental data or existing theoretical results in the literature. The calculation technique presented in this paper serves as a predictive formalism for further studies of larger monomer clusters, for which experimental data is unreliable or unavailable.",
journal = "Optical Materials: X",
title = "The d-d transitions and ligand field parameters for Cr3+/Co2+ doped (Mg, Zn)Al2O4: Multi-reference Ab initio investigations",
volume = "16",
pages = "100188",
doi = "10.1016/j.omx.2022.100188"
}

Andreici Etimie, E. L., Avram, N. M.,& Brik, M. G.. (2022). The d-d transitions and ligand field parameters for Cr3+/Co2+ doped (Mg, Zn)Al2O4: Multi-reference Ab initio investigations. in Optical Materials: X, 16, 100188.
https://doi.org/10.1016/j.omx.2022.100188

Andreici Etimie EL, Avram NM, Brik MG. The d-d transitions and ligand field parameters for Cr3+/Co2+ doped (Mg, Zn)Al2O4: Multi-reference Ab initio investigations. in Optical Materials: X. 2022;16:100188.
doi:10.1016/j.omx.2022.100188 .

Andreici Etimie, E. L., Avram, Nicolae M., Brik, Mikhail G., "The d-d transitions and ligand field parameters for Cr3+/Co2+ doped (Mg, Zn)Al2O4: Multi-reference Ab initio investigations" in Optical Materials: X, 16 (2022):100188,
https://doi.org/10.1016/j.omx.2022.100188 . .

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 . .