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  - Srivastava, Alok M.
AU  - Brik, Mikhail G.
AU  - Beers, William W.
AU  - Ma, Chong-Geng
AU  - Piasecki, Michal
AU  - Cohen, William E.
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10610
AB  - A comparative study of Eu3+ luminescence in an isostructural series of phosphate and vanadate compounds correlates the hypersensitivity of the 5D0→7F2 transition to the covalence and polarizability of the (XO4)3- (X = P, V) polyanion. The intensity of this transition, as measured by the ratio, [Formula presented], is always higher in the vanadate system [R (PO4)3-« R (VO4)3-]. Electronic energy band structure of these systems establishes higher covalence and polarizability of the (VO4)3- polyanion, which is due to strong V 3 d - O 2p covalent interaction via hybridization. The difference in the intensity of the hypersensitive transition between the phosphate and vanadate systems is consistent with the prediction of the ligand dipolar polarization model for the 4f-4f dipolar intensities. Our analysis supports the polarizability of (XO4)3- (X = P, V) over local site distortion effects as the intensity enhancing mechanism of the 5D0→7F2 transition. It is pointed out that the hybridization effect that serves as the source of the intensity of hypersensitive transition also accounts for the origin of second harmonic generation (SHG) in Li3VO4 and its absence in Li3PO4. © 2023 Elsevier B.V.
T2  - Journal of Luminescence
T1  - Intensity of the Eu3+ hypersensitive transition in isostructural phosphate and vanadate compounds
VL  - 257
DO  - 10.1016/j.jlumin.2023.119709
ER  - 

@article{
author = "Srivastava, Alok M. and Brik, Mikhail G. and Beers, William W. and Ma, Chong-Geng and Piasecki, Michal and Cohen, William E.",
year = "2023",
abstract = "A comparative study of Eu3+ luminescence in an isostructural series of phosphate and vanadate compounds correlates the hypersensitivity of the 5D0→7F2 transition to the covalence and polarizability of the (XO4)3- (X = P, V) polyanion. The intensity of this transition, as measured by the ratio, [Formula presented], is always higher in the vanadate system [R (PO4)3-« R (VO4)3-]. Electronic energy band structure of these systems establishes higher covalence and polarizability of the (VO4)3- polyanion, which is due to strong V 3 d - O 2p covalent interaction via hybridization. The difference in the intensity of the hypersensitive transition between the phosphate and vanadate systems is consistent with the prediction of the ligand dipolar polarization model for the 4f-4f dipolar intensities. Our analysis supports the polarizability of (XO4)3- (X = P, V) over local site distortion effects as the intensity enhancing mechanism of the 5D0→7F2 transition. It is pointed out that the hybridization effect that serves as the source of the intensity of hypersensitive transition also accounts for the origin of second harmonic generation (SHG) in Li3VO4 and its absence in Li3PO4. © 2023 Elsevier B.V.",
journal = "Journal of Luminescence",
title = "Intensity of the Eu3+ hypersensitive transition in isostructural phosphate and vanadate compounds",
volume = "257",
doi = "10.1016/j.jlumin.2023.119709"
}

Srivastava, A. M., Brik, M. G., Beers, W. W., Ma, C., Piasecki, M.,& Cohen, W. E.. (2023). Intensity of the Eu3+ hypersensitive transition in isostructural phosphate and vanadate compounds. in Journal of Luminescence, 257.
https://doi.org/10.1016/j.jlumin.2023.119709

Srivastava AM, Brik MG, Beers WW, Ma C, Piasecki M, Cohen WE. Intensity of the Eu3+ hypersensitive transition in isostructural phosphate and vanadate compounds. in Journal of Luminescence. 2023;257.
doi:10.1016/j.jlumin.2023.119709 .

Srivastava, Alok M., Brik, Mikhail G., Beers, William W., Ma, Chong-Geng, Piasecki, Michal, Cohen, William E., "Intensity of the Eu3+ hypersensitive transition in isostructural phosphate and vanadate compounds" in Journal of Luminescence, 257 (2023),
https://doi.org/10.1016/j.jlumin.2023.119709 . .

TY  - JOUR
AU  - Dramićanin, Miroslav
AU  - Marciniak, Lukasz
AU  - Kuzman, Sanja
AU  - Piotrowski, Wojciech
AU  - Ristić, Zoran
AU  - Periša, Jovana
AU  - Evans, Ivana
AU  - Mitrić, Jelena
AU  - Đorđević, Vesna
AU  - Tadić, Julijana D.
AU  - Brik, Mikhail G.
AU  - Ma, Chong-Geng
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10439
AB  - The near-infrared luminescence of Ca6Ba(PO4)4O:Mn5+ is demonstrated and explained. When excited into the broad and strong absorption band that spans the 500–1000 nm spectral range, this phosphor provides an ultranarrow (FWHM = 5 nm) emission centered at 1140 nm that originates from a spin-forbidden 1E → 3A2 transition with a 37.5% internal quantum efficiency and an excited-state lifetime of about 350 μs. We derived the crystal field and Racah parameters and calculated the appropriate Tanabe–Sugano diagram for this phosphor. We found that 1E emission quenches due to the thermally-assisted cross-over with the 3T2 state and that the relatively high Debye temperature of 783 K of Ca6Ba(PO4)4O facilitates efficient emission. Since Ca6Ba(PO4)4O also provides efficient yellow emission of the Eu2+ dopant, we calculated and explained its electronic band structure, the partial and total density of states, effective Mulliken charges of all ions, elastic constants, Debye temperature, and vibrational spectra. Finally, we demonstrated the application of phosphor in a luminescence intensity ratio thermometry and obtained a relative sensitivity of 1.92%K−1 and a temperature resolution of 0.2 K in the range of physiological temperatures.
T2  - Light: Science & Applications
T1  - Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry
VL  - 11
IS  - 1
SP  - 279
DO  - 10.1038/s41377-022-00958-7
ER  - 

@article{
author = "Dramićanin, Miroslav and Marciniak, Lukasz and Kuzman, Sanja and Piotrowski, Wojciech and Ristić, Zoran and Periša, Jovana and Evans, Ivana and Mitrić, Jelena and Đorđević, Vesna and Tadić, Julijana D. and Brik, Mikhail G. and Ma, Chong-Geng",
year = "2022",
abstract = "The near-infrared luminescence of Ca6Ba(PO4)4O:Mn5+ is demonstrated and explained. When excited into the broad and strong absorption band that spans the 500–1000 nm spectral range, this phosphor provides an ultranarrow (FWHM = 5 nm) emission centered at 1140 nm that originates from a spin-forbidden 1E → 3A2 transition with a 37.5% internal quantum efficiency and an excited-state lifetime of about 350 μs. We derived the crystal field and Racah parameters and calculated the appropriate Tanabe–Sugano diagram for this phosphor. We found that 1E emission quenches due to the thermally-assisted cross-over with the 3T2 state and that the relatively high Debye temperature of 783 K of Ca6Ba(PO4)4O facilitates efficient emission. Since Ca6Ba(PO4)4O also provides efficient yellow emission of the Eu2+ dopant, we calculated and explained its electronic band structure, the partial and total density of states, effective Mulliken charges of all ions, elastic constants, Debye temperature, and vibrational spectra. Finally, we demonstrated the application of phosphor in a luminescence intensity ratio thermometry and obtained a relative sensitivity of 1.92%K−1 and a temperature resolution of 0.2 K in the range of physiological temperatures.",
journal = "Light: Science & Applications",
title = "Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry",
volume = "11",
number = "1",
pages = "279",
doi = "10.1038/s41377-022-00958-7"
}

Dramićanin, M., Marciniak, L., Kuzman, S., Piotrowski, W., Ristić, Z., Periša, J., Evans, I., Mitrić, J., Đorđević, V., Tadić, J. D., Brik, M. G.,& Ma, C.. (2022). Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry. in Light: Science & Applications, 11(1), 279.
https://doi.org/10.1038/s41377-022-00958-7

Dramićanin M, Marciniak L, Kuzman S, Piotrowski W, Ristić Z, Periša J, Evans I, Mitrić J, Đorđević V, Tadić JD, Brik MG, Ma C. Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry. in Light: Science & Applications. 2022;11(1):279.
doi:10.1038/s41377-022-00958-7 .

Dramićanin, Miroslav, Marciniak, Lukasz, Kuzman, Sanja, Piotrowski, Wojciech, Ristić, Zoran, Periša, Jovana, Evans, Ivana, Mitrić, Jelena, Đorđević, Vesna, Tadić, Julijana D., Brik, Mikhail G., Ma, Chong-Geng, "Mn5+-activated Ca6Ba(PO4)4O near-infrared phosphor and its application in luminescence thermometry" in Light: Science & Applications, 11, no. 1 (2022):279,
https://doi.org/10.1038/s41377-022-00958-7 . .

TY  - JOUR
AU  - Mironova-Ulmane, Nina
AU  - Brik, Mikhail G.
AU  - Grube, Jurgis
AU  - Krieke, Guna
AU  - Kemere, Meldra
AU  - Antuzevics, Andris
AU  - Gabrusenoks, E.
AU  - Skvortsova, Vera N.
AU  - Elsts, Edgars
AU  - Sarakovskis, Anatolijs
AU  - Piasecki, Michal
AU  - Popov, Anatoli I.
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10397
AB  - The optical spectra of a single crystal of α-Al2O3Cr3+ were studied in a wide temperature range. The crystal was demonstrated to have a potential for optical thermometric applications. Three ways of measuring temperature were tested and analyzed: i) luminescence intensity ratio of the R1 and R2 lines; ii) change of the full width of half maxima of the R1 and R2 lines, and iii) thermal shifts of the R1 and R2 lines maxima. The highest absolute and relative sensitivities were obtained at cryogenic temperatures. In addition, the thermal shifts of the R lines were analyzed using the McCumber-Sturge equation to estimate the Debye temperature and the electron-vibrational interaction parameter.
T2  - Optical Materials
T1  - EPR, optical and thermometric studies of Cr3+ ions in the α-Al2O3 synthetic single crystal
VL  - 132
SP  - 112859
DO  - 10.1016/j.optmat.2022.112859
ER  - 

@article{
author = "Mironova-Ulmane, Nina and Brik, Mikhail G. and Grube, Jurgis and Krieke, Guna and Kemere, Meldra and Antuzevics, Andris and Gabrusenoks, E. and Skvortsova, Vera N. and Elsts, Edgars and Sarakovskis, Anatolijs and Piasecki, Michal and Popov, Anatoli I.",
year = "2022",
abstract = "The optical spectra of a single crystal of α-Al2O3Cr3+ were studied in a wide temperature range. The crystal was demonstrated to have a potential for optical thermometric applications. Three ways of measuring temperature were tested and analyzed: i) luminescence intensity ratio of the R1 and R2 lines; ii) change of the full width of half maxima of the R1 and R2 lines, and iii) thermal shifts of the R1 and R2 lines maxima. The highest absolute and relative sensitivities were obtained at cryogenic temperatures. In addition, the thermal shifts of the R lines were analyzed using the McCumber-Sturge equation to estimate the Debye temperature and the electron-vibrational interaction parameter.",
journal = "Optical Materials",
title = "EPR, optical and thermometric studies of Cr3+ ions in the α-Al2O3 synthetic single crystal",
volume = "132",
pages = "112859",
doi = "10.1016/j.optmat.2022.112859"
}

Mironova-Ulmane, N., Brik, M. G., Grube, J., Krieke, G., Kemere, M., Antuzevics, A., Gabrusenoks, E., Skvortsova, V. N., Elsts, E., Sarakovskis, A., Piasecki, M.,& Popov, A. I.. (2022). EPR, optical and thermometric studies of Cr3+ ions in the α-Al2O3 synthetic single crystal. in Optical Materials, 132, 112859.
https://doi.org/10.1016/j.optmat.2022.112859

Mironova-Ulmane N, Brik MG, Grube J, Krieke G, Kemere M, Antuzevics A, Gabrusenoks E, Skvortsova VN, Elsts E, Sarakovskis A, Piasecki M, Popov AI. EPR, optical and thermometric studies of Cr3+ ions in the α-Al2O3 synthetic single crystal. in Optical Materials. 2022;132:112859.
doi:10.1016/j.optmat.2022.112859 .

Mironova-Ulmane, Nina, Brik, Mikhail G., Grube, Jurgis, Krieke, Guna, Kemere, Meldra, Antuzevics, Andris, Gabrusenoks, E., Skvortsova, Vera N., Elsts, Edgars, Sarakovskis, Anatolijs, Piasecki, Michal, Popov, Anatoli I., "EPR, optical and thermometric studies of Cr3+ ions in the α-Al2O3 synthetic single crystal" in Optical Materials, 132 (2022):112859,
https://doi.org/10.1016/j.optmat.2022.112859 . .

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 . .

TY  - JOUR
AU  - Ristić, Zoran
AU  - Đorđević, Vesna R.
AU  - Medić, Mina M.
AU  - Kuzman, Sanja
AU  - Brik, Mikhail G.
AU  - Antić, Željka
AU  - Dramićanin, Miroslav
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9910
AB  - This paper presents the Cr3+-activated Mg2TiO4 phosphor temperature dependance of its near infrared luminescence and its potential in the optical thermometry applications. In this respect, temperature dependences of three emission features were tested over the broad temperature range (10–500 K): (i) the luminescence intensity ratio (LIR) between emissions from 4T2→4A2 and 2E→4A2 transitions, (ii) the emission lifetime, and (iii) the shift of the 2E→4A2 emission band. We observed that LIR follows the Boltzmann equation for T > 300 K with the maximal value of relative sensitivity of 1.73 %K−1. The lifetime value of the 2E→4A2 transition strongly decreases with temperature with a maximal relative sensitivity of about 0.75 %K−1 at around 430K. Finally, the shift of the emission band is about 65 cm−1 over the complete temperature range.
T2  - Optical Materials
T1  - Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission
VL  - 120
SP  - 111468
DO  - 10.1016/j.optmat.2021.111468
ER  - 

@article{
author = "Ristić, Zoran and Đorđević, Vesna R. and Medić, Mina M. and Kuzman, Sanja and Brik, Mikhail G. and Antić, Željka and Dramićanin, Miroslav",
year = "2021",
abstract = "This paper presents the Cr3+-activated Mg2TiO4 phosphor temperature dependance of its near infrared luminescence and its potential in the optical thermometry applications. In this respect, temperature dependences of three emission features were tested over the broad temperature range (10–500 K): (i) the luminescence intensity ratio (LIR) between emissions from 4T2→4A2 and 2E→4A2 transitions, (ii) the emission lifetime, and (iii) the shift of the 2E→4A2 emission band. We observed that LIR follows the Boltzmann equation for T > 300 K with the maximal value of relative sensitivity of 1.73 %K−1. The lifetime value of the 2E→4A2 transition strongly decreases with temperature with a maximal relative sensitivity of about 0.75 %K−1 at around 430K. Finally, the shift of the emission band is about 65 cm−1 over the complete temperature range.",
journal = "Optical Materials",
title = "Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission",
volume = "120",
pages = "111468",
doi = "10.1016/j.optmat.2021.111468"
}

Ristić, Z., Đorđević, V. R., Medić, M. M., Kuzman, S., Brik, M. G., Antić, Ž.,& Dramićanin, M.. (2021). Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission. in Optical Materials, 120, 111468.
https://doi.org/10.1016/j.optmat.2021.111468

Ristić Z, Đorđević VR, Medić MM, Kuzman S, Brik MG, Antić Ž, Dramićanin M. Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission. in Optical Materials. 2021;120:111468.
doi:10.1016/j.optmat.2021.111468 .

Ristić, Zoran, Đorđević, Vesna R., Medić, Mina M., Kuzman, Sanja, Brik, Mikhail G., Antić, Željka, Dramićanin, Miroslav, "Temperature dependence of the Cr3+-DOPED Mg2TiO4 near-infrared emission" in Optical Materials, 120 (2021):111468,
https://doi.org/10.1016/j.optmat.2021.111468 . .

TY  - JOUR
AU  - Dramićanin, Miroslav
AU  - Milićević, Bojana R.
AU  - Đorđević, Vesna R.
AU  - Ristić, Zoran
AU  - Zhou, Jianbang
AU  - Milivojević, Dušan
AU  - Papan, Jelena
AU  - Brik, Mikhail G.
AU  - Ma, Chong‐Geng
AU  - Srivastava, Alok M
AU  - Wu, Mingmei
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8360
AB  - Luminescence of monoclinic lithium metatitanate (Li2TiO3) powders activated with different quantities of Mn4+ is studied in detail. Its strong deep-red emission arising from the Mn4+ 2Eg → 4A2g spin forbidden transition is centered at around 688 nm and is suitable for luminescence thermometry. Structural and electron paramagnetic resonance analyses show that Mn4+ ions are equally distributed in two almost identical Ti4+ sites in which they are octahedrally coordinated by six oxygen ions. Calculations based on the exchange charge model of the crystal field provided values of Racah parameters (B=760 cm−1, C= 2993 cm−1), crystal-field splitting Dq= 2043 cm−1, and the nephelauxetic parameter β1=0.9775. The maximal quantum efficiency of 24.1% at room temperature is found for 0.126% Mn4+ concentration. Temperature quenching of emission occurs by a cross-over via 4T2 excited state of the Mn4+ ions with T1/2=262 K and is quite favorable for the application in the lifetime-based luminescence thermometry since relative changes in emission decay values are exceptionally-large (around 3.21% at room temperature). We derived theoretical expressions for the temperature dependence of the absolute and relative sensitivities and discuss the influence of host material properties on lifetime sensitivities. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
T2  - ChemistrySelect
T1  - Li2TiO3:Mn4+ Deep‐Red Phosphor for the Lifetime‐Based Luminescence Thermometry
VL  - 4
IS  - 24
SP  - 7067
EP  - 7075
DO  - 10.1002/slct.201901590
ER  - 

@article{
author = "Dramićanin, Miroslav and Milićević, Bojana R. and Đorđević, Vesna R. and Ristić, Zoran and Zhou, Jianbang and Milivojević, Dušan and Papan, Jelena and Brik, Mikhail G. and Ma, Chong‐Geng and Srivastava, Alok M and Wu, Mingmei",
year = "2019",
abstract = "Luminescence of monoclinic lithium metatitanate (Li2TiO3) powders activated with different quantities of Mn4+ is studied in detail. Its strong deep-red emission arising from the Mn4+ 2Eg → 4A2g spin forbidden transition is centered at around 688 nm and is suitable for luminescence thermometry. Structural and electron paramagnetic resonance analyses show that Mn4+ ions are equally distributed in two almost identical Ti4+ sites in which they are octahedrally coordinated by six oxygen ions. Calculations based on the exchange charge model of the crystal field provided values of Racah parameters (B=760 cm−1, C= 2993 cm−1), crystal-field splitting Dq= 2043 cm−1, and the nephelauxetic parameter β1=0.9775. The maximal quantum efficiency of 24.1% at room temperature is found for 0.126% Mn4+ concentration. Temperature quenching of emission occurs by a cross-over via 4T2 excited state of the Mn4+ ions with T1/2=262 K and is quite favorable for the application in the lifetime-based luminescence thermometry since relative changes in emission decay values are exceptionally-large (around 3.21% at room temperature). We derived theoretical expressions for the temperature dependence of the absolute and relative sensitivities and discuss the influence of host material properties on lifetime sensitivities. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim",
journal = "ChemistrySelect",
title = "Li2TiO3:Mn4+ Deep‐Red Phosphor for the Lifetime‐Based Luminescence Thermometry",
volume = "4",
number = "24",
pages = "7067-7075",
doi = "10.1002/slct.201901590"
}

Dramićanin, M., Milićević, B. R., Đorđević, V. R., Ristić, Z., Zhou, J., Milivojević, D., Papan, J., Brik, M. G., Ma, C., Srivastava, A. M.,& Wu, M.. (2019). Li2TiO3:Mn4+ Deep‐Red Phosphor for the Lifetime‐Based Luminescence Thermometry. in ChemistrySelect, 4(24), 7067-7075.
https://doi.org/10.1002/slct.201901590

Dramićanin M, Milićević BR, Đorđević VR, Ristić Z, Zhou J, Milivojević D, Papan J, Brik MG, Ma C, Srivastava AM, Wu M. Li2TiO3:Mn4+ Deep‐Red Phosphor for the Lifetime‐Based Luminescence Thermometry. in ChemistrySelect. 2019;4(24):7067-7075.
doi:10.1002/slct.201901590 .

Dramićanin, Miroslav, Milićević, Bojana R., Đorđević, Vesna R., Ristić, Zoran, Zhou, Jianbang, Milivojević, Dušan, Papan, Jelena, Brik, Mikhail G., Ma, Chong‐Geng, Srivastava, Alok M, Wu, Mingmei, "Li2TiO3:Mn4+ Deep‐Red Phosphor for the Lifetime‐Based Luminescence Thermometry" in ChemistrySelect, 4, no. 24 (2019):7067-7075,
https://doi.org/10.1002/slct.201901590 . .

TY  - JOUR
AU  - Wang, Y.
AU  - Chen, Wenbo
AU  - Liu, Feilong
AU  - Yang, D. W.
AU  - Tian, Ya
AU  - Ma, Chong-Geng
AU  - Dramićanin, Miroslav
AU  - Brik, Mikhail G.
PY  - 2019
UR  - https://linkinghub.elsevier.com/retrieve/pii/S2211379719305327
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8091
AB  - Modern methods of theoretical and experimental materials engineering can be greatly facilitated by reliably established guiding trends that set directions for a smart search for new materials with enhanced performance. Those trends can be derived from a thorough analysis of large arrays of the experimental data, obtained both experimentally and theoretically. In the present paper, the structural, elastic, and electronic properties of 30 spinel compounds AB 2 X 4 (A = Be, Mg, Ca, Sr, Ba; B = Al, Ga, In; X = O, S) were investigated using the CRYSTAL14 program. For the first time the lattice constants, bulk moduli, band gaps and density of states for these 30 spinels were systematically calculated and analyzed. Influence of the cation and anion variation on the above-mentioned properties was highlighted. Several relations between lattice constants, bulk modulus and ionic radii, electronegativities of constituting ions were found. Several linear equations are proposed, which provide a convenient way to predict the lattice constants and bulk moduli of isostructural spinels. © 2019
T2  - Results in Physics
T1  - High-throughput first-principles calculations as a powerful guiding tool for materials engineering: Case study of the AB2X4 (A = Be, Mg, Ca, Sr, ba; B = Al, Ga, in; X = O, S) spinel compounds
VL  - 13
SP  - 102180
DO  - 10.1016/j.rinp.2019.102180
ER  - 

@article{
author = "Wang, Y. and Chen, Wenbo and Liu, Feilong and Yang, D. W. and Tian, Ya and Ma, Chong-Geng and Dramićanin, Miroslav and Brik, Mikhail G.",
year = "2019",
abstract = "Modern methods of theoretical and experimental materials engineering can be greatly facilitated by reliably established guiding trends that set directions for a smart search for new materials with enhanced performance. Those trends can be derived from a thorough analysis of large arrays of the experimental data, obtained both experimentally and theoretically. In the present paper, the structural, elastic, and electronic properties of 30 spinel compounds AB 2 X 4 (A = Be, Mg, Ca, Sr, Ba; B = Al, Ga, In; X = O, S) were investigated using the CRYSTAL14 program. For the first time the lattice constants, bulk moduli, band gaps and density of states for these 30 spinels were systematically calculated and analyzed. Influence of the cation and anion variation on the above-mentioned properties was highlighted. Several relations between lattice constants, bulk modulus and ionic radii, electronegativities of constituting ions were found. Several linear equations are proposed, which provide a convenient way to predict the lattice constants and bulk moduli of isostructural spinels. © 2019",
journal = "Results in Physics",
title = "High-throughput first-principles calculations as a powerful guiding tool for materials engineering: Case study of the AB2X4 (A = Be, Mg, Ca, Sr, ba; B = Al, Ga, in; X = O, S) spinel compounds",
volume = "13",
pages = "102180",
doi = "10.1016/j.rinp.2019.102180"
}

Wang, Y., Chen, W., Liu, F., Yang, D. W., Tian, Y., Ma, C., Dramićanin, M.,& Brik, M. G.. (2019). High-throughput first-principles calculations as a powerful guiding tool for materials engineering: Case study of the AB2X4 (A = Be, Mg, Ca, Sr, ba; B = Al, Ga, in; X = O, S) spinel compounds. in Results in Physics, 13, 102180.
https://doi.org/10.1016/j.rinp.2019.102180

Wang Y, Chen W, Liu F, Yang DW, Tian Y, Ma C, Dramićanin M, Brik MG. High-throughput first-principles calculations as a powerful guiding tool for materials engineering: Case study of the AB2X4 (A = Be, Mg, Ca, Sr, ba; B = Al, Ga, in; X = O, S) spinel compounds. in Results in Physics. 2019;13:102180.
doi:10.1016/j.rinp.2019.102180 .

Wang, Y., Chen, Wenbo, Liu, Feilong, Yang, D. W., Tian, Ya, Ma, Chong-Geng, Dramićanin, Miroslav, Brik, Mikhail G., "High-throughput first-principles calculations as a powerful guiding tool for materials engineering: Case study of the AB2X4 (A = Be, Mg, Ca, Sr, ba; B = Al, Ga, in; X = O, S) spinel compounds" in Results in Physics, 13 (2019):102180,
https://doi.org/10.1016/j.rinp.2019.102180 . .

TY  - JOUR
AU  - Zhou, Qiang
AU  - Dolgov, Leonid
AU  - Srivastava, Alok M
AU  - Zhou, Lei
AU  - Wang, Zhengliang
AU  - Shi, Jianxin
AU  - Dramićanin, Miroslav
AU  - Brik, Mikhail G.
AU  - Wu, Mingmei
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7638
AB  - Transition-metal activated phosphors are an important family of luminescent materials that can produce white light with an outstanding color rendering index and correlated color temperature for use in light-emitting diodes.  In recent years, work in this quite “hot” research field has focused on the development of Mn2+ and Mn4+ activated red phosphors. In this review article, we provide an overview of recent studies on Mn2+ and Mn4+ doped phosphors, including detailed synthesis routes (solid-state reaction and wet-chemical synthesis) and description of luminescence mechanisms and phosphors’ behaviors; discuss their promising applications in white light-emitting diodes; and present an extensive list of references to representative works in this field.
T2  - Journal of Materials Chemistry C
T1  - Mn 2+ and Mn 4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review
VL  - 6
IS  - 11
SP  - 2652
EP  - 2671
DO  - 10.1039/C8TC00251G
ER  - 

@article{
author = "Zhou, Qiang and Dolgov, Leonid and Srivastava, Alok M and Zhou, Lei and Wang, Zhengliang and Shi, Jianxin and Dramićanin, Miroslav and Brik, Mikhail G. and Wu, Mingmei",
year = "2018",
abstract = "Transition-metal activated phosphors are an important family of luminescent materials that can produce white light with an outstanding color rendering index and correlated color temperature for use in light-emitting diodes.  In recent years, work in this quite “hot” research field has focused on the development of Mn2+ and Mn4+ activated red phosphors. In this review article, we provide an overview of recent studies on Mn2+ and Mn4+ doped phosphors, including detailed synthesis routes (solid-state reaction and wet-chemical synthesis) and description of luminescence mechanisms and phosphors’ behaviors; discuss their promising applications in white light-emitting diodes; and present an extensive list of references to representative works in this field.",
journal = "Journal of Materials Chemistry C",
title = "Mn 2+ and Mn 4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review",
volume = "6",
number = "11",
pages = "2652-2671",
doi = "10.1039/C8TC00251G"
}

Zhou, Q., Dolgov, L., Srivastava, A. M., Zhou, L., Wang, Z., Shi, J., Dramićanin, M., Brik, M. G.,& Wu, M.. (2018). Mn 2+ and Mn 4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review. in Journal of Materials Chemistry C, 6(11), 2652-2671.
https://doi.org/10.1039/C8TC00251G

Zhou Q, Dolgov L, Srivastava AM, Zhou L, Wang Z, Shi J, Dramićanin M, Brik MG, Wu M. Mn 2+ and Mn 4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review. in Journal of Materials Chemistry C. 2018;6(11):2652-2671.
doi:10.1039/C8TC00251G .

Zhou, Qiang, Dolgov, Leonid, Srivastava, Alok M, Zhou, Lei, Wang, Zhengliang, Shi, Jianxin, Dramićanin, Miroslav, Brik, Mikhail G., Wu, Mingmei, "Mn 2+ and Mn 4+ red phosphors: synthesis, luminescence and applications in WLEDs. A review" in Journal of Materials Chemistry C, 6, no. 11 (2018):2652-2671,
https://doi.org/10.1039/C8TC00251G . .