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Santamaría G, Fernández-Ruiz T, García-Lastra JM, García-Fernández P, Sánchez-Movellán I, Moreno M, Aramburu JA. Understanding Pressure Effects on Structural, Optical, and Magnetic Properties of CsMnF 4 and Other 3d n Compounds. Inorg Chem 2024; 63:13231-13243. [PMID: 38984802 PMCID: PMC11271007 DOI: 10.1021/acs.inorgchem.4c00599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 07/11/2024]
Abstract
The pressure dependence of structural, optical, and magnetic properties of the layered compound CsMnF4 are explored through first-principles calculations. The structure at ambient pressure does not arise from a Jahn-Teller effect but from an orthorhombic instability on MnF63- units in the tetragonal parent phase, while there is a P4/n → P4 structural phase transition at P = 40 GPa discarding a spin crossover transition from S = 2 to S = 1. The present results reasonably explain the evolution of spin-allowed d-d transitions under pressure, showing that the first transition undergoes a red-shift under pressure following the orthorhombic distortion in the layer plane. The energy of such a transition at zero pressure is nearly twice that observed in Na3MnF6 due to the internal electric field and the orthorhombic distortion also involved in K2CuF4. The reasons for the lack of orthorhombic distortion in K2MF4 (M = Ni, Mn) or CsFeF4 are also discussed in detail. The present calculations confirm the ferromagnetic ordering of layers in CsMnF4 at zero pressure and predict a shift to an antiferromagnetic phase for pressures above 15 GPa consistent with the reduction of the orthorhombicity of the MnF63- units. This study underlines the usefulness of first-principles calculations for a right interpretation of experimental findings.
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Affiliation(s)
- Guillermo Santamaría
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
- Donostia
International Physics Center (DIPC), 20018 Donostia, Euskadi, Spain
- Laboratory
for Chemistry of Novel Materials, University
of Mons, 7000 Mons, Belgium
| | - Toraya Fernández-Ruiz
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
| | - Juan María García-Lastra
- Department
of Energy Conversion and Storage, Technical
University of Denmark, Anker Engelunds Vej. Building 301, 2800 Kgs. Lyngby, Denmark
| | - Pablo García-Fernández
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
| | - Inés Sánchez-Movellán
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
| | - Miguel Moreno
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
| | - José Antonio Aramburu
- Departamento
de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, 39005 Santander, Spain
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2
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Sánchez-Movellán I, Aramburu JA, Moreno M. Chemical Bonding, 10Dq Parameter and Superexchange in the Model Compound KNiF 3. Chemphyschem 2024; 25:e202400006. [PMID: 38573167 DOI: 10.1002/cphc.202400006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/05/2024]
Abstract
The cubic field splitting parameter, 10Dq, plays a central role in the ligand field theory on insulating transition metal compounds. Experimental data obtained in the last 50 years prove that 10Dq is highly dependent on changes of the metal-ligand distance, R, induced by chemical or applied pressures. Despite this fact has important consequences on optical and magnetic properties of such compounds, its actual origin is still controversial. Seeking to clarify that crucial issue, this work is focused on KNiF3, a reference system among insulating transition metal compounds. By means of first principles calculations we show that, contrary to what is usually thought, the R-dependence of 10Dq arises neither from the crystal field contribution nor from the covalent admixture of 3d(Ni) with valence 2p(F) orbitals. Indeed, we prove that it is mainly due to the residual covalency with deep 2s(F) orbitals, highly sensitive to R variations. As a salient feature the present calculations show that the 3d-2pσ and 3d-2pπ admixtures raise practically equal the energy of antibonding eg and t2g orbitals of NiF6 4- units in KNiF3 thus leading to a null contribution to 10Dq. This conclusion is not significantly altered when considering the change of covalency on passing from the ground state 3A2(t2g 6eg 2) to the excited state 3T2(t2g 5eg 3). The different influence of chemical bonding on the superexchange constant, J, and 10Dq is also discussed in a second step. It is pointed out that the strong dependence of J upon R can hardly be explained through the behavior of the 3d-2pσ covalency derived for a single NiF6 4- unit. For the sake of clarity, the meaning of 10Dq is also briefly analyzed.
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Affiliation(s)
- Inés Sánchez-Movellán
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, 39005, Santander, Spain
| | - José Antonio Aramburu
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, 39005, Santander, Spain
| | - Miguel Moreno
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, 39005, Santander, Spain
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3
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Yusa H, Miyakawa M. High-Pressure Synthesis of Corundum-Type Ga 2O 3:Cr 3+ and Application of Its Fluorescence to the Pressure Scale. Inorg Chem 2024; 63:2695-2700. [PMID: 38252614 DOI: 10.1021/acs.inorgchem.3c04028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cr3+-doped Ga2O3 crystals with a corundum structure were synthesized at high temperature and high pressure, and their excitation as well as fluorescence properties were evaluated. The crystals were green under white light illumination but deep red when exposed to ultraviolet light. This can mainly be attributed to R1 and R2 fluorescence spectra caused by the Cr3+ transition. The pressure-dependence of their fluorescence spectra is comparable with ruby (Al2O3:Cr3+), which is currently often used as a pressure scale. The excitation spectrum was shifted to the long-wavelength side compared with ruby, which enabled excitation with long-wavelength lasers, even if the pressure effect is considered. In addition, the R1 and R2 peaks were well-separated with increasing pressure, which might have advantages over the ruby scale.
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Affiliation(s)
- Hitoshi Yusa
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki (NIMS), Tsukuba 305-0044, Ibaraki, Japan
| | - Masashi Miyakawa
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki (NIMS), Tsukuba 305-0044, Ibaraki, Japan
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4
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Leśniewski T. Evolution of the full energy structure of Mn 4+ in fluoride phosphors under high pressure conditions. Phys Chem Chem Phys 2023; 25:14449-14462. [PMID: 37184713 DOI: 10.1039/d3cp01045g] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This paper analyzes the photoluminescence excitation and emission spectra of fluoride phosphors doped with Mn4+: KNaSiF6:Mn4+, Rb2GeF6:Mn4+, and Na3HTiF8:Mn4+ under high pressure conditions. From the optical spectra, the pressure-dependent energies of optically active 4T2, 4T1, and 2E crystal field subterms of Mn4+ have been determined in the 0-30 GPa pressure range. A strong blueshift of the 4T2 and 4T1 subterms was found, as expected from the Tanabe-Sugano diagram for Mn4+ (d3). At the same time, the 2E emitting state exhibited a redshift under pressure - an effect opposite to the prediction of the Tanabe-Sugano diagram. This is a manifestation of the pressure-driven nephelauxetic effect, governed by pressure induced changes of Racah parameters, which demonstrates the necessity of taking into account the Racah parameters for a correct description of Mn4+ emission under pressure. The high pressure experimental data allowed to determine the pressure dependence of crystal field strength parameter Dq and Racah parameters B and C. Finally, obtaining the pressure dependence of Dq and Racah parameters allowed to calculate the full energy structure of the d3 configuration of Mn4+ in KNaSiF6, Rb2GeF6, and Na3HTiF8 in the pressure range of 0-30 GPa. The calculations reproduced the redshift of the 2E emitting state under pressure, as well as gave the pressure shift direction and magnitude for all crystal field subterms of Mn4+ up to 50 000 cm-1 (i.e. the equivalent of the Tanabe-Sugano diagram for high-pressure experiments). The approach presented in this paper can be easily extended for calculating the energy structure of materials doped with isoelectronic Cr3+ as well as other transition metal ions.
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Affiliation(s)
- Tadeusz Leśniewski
- Institute of Experimental Physics, Faculty of Mathematics, Physic and Informatics, University of Gdańsk, 80-308 Gdańsk, Poland.
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Carrasco‐Busturia D, Sánchez‐Movellán I, Tygesen AS, Bhowmik A, García‐Lastra JM, Aramburu JA, Moreno M. Red Shift in Optical Excitations on Layered Copper Perovskites under Pressure: Role of the Orthorhombic Instability. Chemistry 2023; 29:e202202933. [PMID: 36322429 PMCID: PMC10107362 DOI: 10.1002/chem.202202933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Indexed: 11/06/2022]
Abstract
The red shift under pressure in optical transitions of layered compounds with CuCl6 4- units is explored through first-principles calculations and the analysis of available experimental data. The results on Cu2+ -doped (C2 H5 NH3 )2 CdCl4 , that is taken as a guide, show the existence of a highly anisotropic response to pressure related to a structural instability, driven by a negative force constant, that leads to an orthorhombic geometry of CuCl6 4- units but with a hole displaying a dominant 3z2 -r2 character (z being the direction perpendicular to the layer plane). As a result of such an instability, a pressure of only 3 GPa reduces by 0.21 Å the longest Cu2+ -Cl- distance, lying in the layer plane, while leaving unmodified the two other metal-ligand distances. Owing to this fact, it is shown that the lowest d-d transition would experience a red shift of 0.34 eV while the first allowed charge transfer transition is also found to be red shifted but only by 0.11 eV that reasonably concurs with the experimental value. The parallel study on Jahn-Teller systems CdCl2 :Cu2+ and NaCl:Cu2+ involving tetragonal elongated CuCl6 4- units shows that the reduction of the long axis by a pressure of 3 GPa is three times smaller than that for the layered (C2 H5 NH3 )2 CdCl4 :Cu2+ compound. Accordingly, the optical transitions of such systems, which involve a positive force constant, are much less sensitive to pressure than in layered compounds. The origin of the red shift under pressure undergone by the lowest d-d and charge transfer transitions of (C2 H5 NH3 )2 CdCl4 :Cu2+ is discussed in detail.
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Affiliation(s)
- David Carrasco‐Busturia
- Department of Energy Conversion and StorageTechnical University of DenmarkAnker Engelunds Vej. Building 3012800 Kgs.LyngbyDenmark
| | - Inés Sánchez‐Movellán
- Departamento de Ciencias de la Tierra y Física de la Materia CondensadaUniversidad de CantabriaAvenida de los Castros s/n39005SantanderSpain
| | - Alexander Sougaard Tygesen
- Department of Energy Conversion and StorageTechnical University of DenmarkAnker Engelunds Vej. Building 3012800 Kgs.LyngbyDenmark
| | - Arghya Bhowmik
- Department of Energy Conversion and StorageTechnical University of DenmarkAnker Engelunds Vej. Building 3012800 Kgs.LyngbyDenmark
| | - Juan María García‐Lastra
- Department of Energy Conversion and StorageTechnical University of DenmarkAnker Engelunds Vej. Building 3012800 Kgs.LyngbyDenmark
| | - José Antonio Aramburu
- Departamento de Ciencias de la Tierra y Física de la Materia CondensadaUniversidad de CantabriaAvenida de los Castros s/n39005SantanderSpain
| | - Miguel Moreno
- Departamento de Ciencias de la Tierra y Física de la Materia CondensadaUniversidad de CantabriaAvenida de los Castros s/n39005SantanderSpain
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Turnbull R, González-Platas J, Rodríguez F, Liang A, Popescu C, He Z, Santamaría-Pérez D, Rodríguez-Hernández P, Muñoz A, Errandonea D. Pressure-Induced Phase Transition and Band Gap Decrease in Semiconducting β-Cu 2V 2O 7. Inorg Chem 2022; 61:3697-3707. [PMID: 35157423 PMCID: PMC8889581 DOI: 10.1021/acs.inorgchem.1c03878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Indexed: 11/30/2022]
Abstract
The understanding of the interplay between crystal structure and electronic structure in semiconductor materials is of great importance due to their potential technological applications. Pressure is an ideal external control parameter to tune the crystal structures of semiconductor materials in order to investigate their emergent piezo-electrical and optical properties. Accordingly, we investigate here the high-pressure behavior of the semiconducting antiferromagnetic material β-Cu2V2O7, finding it undergoes a pressure-induced phase transition to γ-Cu2V2O7 below 4000 atm. The pressure-induced structural and electronic evolutions are investigated by single-crystal X-ray diffraction, absorption spectroscopy and ab initio density functional theory calculations. β-Cu2V2O7 has previously been suggested as a promising photocatalyst for water splitting. Now, these new results suggest that β-Cu2V2O7 could also be of interest with regards to barocaloric effects, due to the low phase -transition pressure, in particular because it is a multiferroic material. Moreover, the phase transition involves an electronic band gap decrease of approximately 0.2 eV (from 1.93 to 1.75 eV) and a large structural volume collapse of approximately 7%.
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Affiliation(s)
- Robin Turnbull
- Departamento
de Física Aplicada - Instituto de Ciencia de Materiales, MALTA
Consolider Team, Universidad de Valencia,
Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia, Spain
| | - Javier González-Platas
- Departamento
de Física - Instituto Universitario de Estudios Avanzados en
Física Atómica, Molecular y Fotónica (IUDEA),
MALTA Consolider Team, Universidad de La
Laguna, Avenida Astrofísico Fco. Sánchez s/n, La Laguna, Tenerife E-38204, Spain
| | - Fernando Rodríguez
- MALTA
Consolider Team, Departamento de Ciencias de la Tierra y Física
de la Materia Condensada, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain
| | - Akun Liang
- Departamento
de Física Aplicada - Instituto de Ciencia de Materiales, MALTA
Consolider Team, Universidad de Valencia,
Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia, Spain
| | - Catalin Popescu
- CELLS-ALBA
Synchrotron Light Facility, 08290 Cerdanyola del Vallès, Barcelona, Spain
| | - Zhangzhen He
- State
Key Laboratory of Structural Chemistry, Fujian Institute of Research
on the Structure of Matter, Chinese Academy
of Sciences, Fuzhou, Fujian 350002, China
| | - David Santamaría-Pérez
- Departamento
de Física Aplicada - Instituto de Ciencia de Materiales, MALTA
Consolider Team, Universidad de Valencia,
Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia, Spain
| | - Plácida Rodríguez-Hernández
- Departamento
de Física, Instituto de Materiales y Nanotecnología,
MALTA Consolider Team, Universidad de La
Laguna, La Laguna, E-38204 Tenerife, Spain
| | - Alfonso Muñoz
- Departamento
de Física, Instituto de Materiales y Nanotecnología,
MALTA Consolider Team, Universidad de La
Laguna, La Laguna, E-38204 Tenerife, Spain
| | - Daniel Errandonea
- Departamento
de Física Aplicada - Instituto de Ciencia de Materiales, MALTA
Consolider Team, Universidad de Valencia,
Edificio de Investigación, C/Dr. Moliner 50, Burjassot, 46100 Valencia, Spain
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7
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Hua H, Ueda J, Xu J, Back M, Tanabe S. High-Pressure Photoluminescence Properties of Cr 3+-Doped LaGaO 3 Perovskites Modulated by Pressure-Induced Phase Transition. Inorg Chem 2021; 60:19253-19262. [PMID: 34874698 DOI: 10.1021/acs.inorgchem.1c03074] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photoluminescence properties of Cr3+-doped LaGaO3 perovskites are investigated by high-pressure spectroscopy. The pressure-induced phase transition from orthorhombic (Pbnm) to rhombohedral (R3̅c) at around 2 GPa is confirmed by Raman spectroscopy. Cr3+-doped LaGaO3 shows deep-red emission peaks around 730 nm due to the zero-phonon line (R-line) and the phonon sidebands, which correspond to Cr3+: 2Eg → 4A2g transitions in the ideal octahedral site and the Cr-Cr pair luminescence (N-line) under ambient condition. Under a high pressure, the R-line shifts to a lower energy at a rate of -13 cm-1/GPa. From the pressure dependence of photoluminescence excitation (PLE) spectra, it is suggested that the redshift of the R-line is caused by the decrease of Racah parameters B and C. Moreover, the N-line luminescence becomes stronger relative to the R-line with increasing pressure and the N-line/R-line can be used to monitor the phase transition pressure. Under a high pressure, the tilt angle of the GaO6 octahedral unit becomes smaller. It implies that the enhanced N-line luminescence is caused by the stronger superexchange interaction between Cr3+ ions due to the increased Cr-O-Cr bond angle closer to 180°.
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Affiliation(s)
- Hansen Hua
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Jumpei Ueda
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Jian Xu
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Michele Back
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Setsuhisa Tanabe
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
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García-Lastra JM, García-Fernández P, Barriuso MT, Aramburu JA, Moreno M. Sharp lines due to Cr³⁺ and Mn²⁺ impurities in insulators: going beyond the usual Tanabe-Sugano approach. J Phys Chem A 2014; 118:2377-84. [PMID: 24580411 DOI: 10.1021/jp5010067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work is aimed at understanding the different behavior of optical sharp lines (corresponding to 10Dq-independent transitions) of Mn(2+) and Cr(3+) in normal and inverted perovskites that cannot be explained within the usual Tanabe-Sugano approach. In particular, we want to clarify why on passing from KMgF3:M to LiBaF3:M (M = Mn(2+), Cr(3+)) the energy, E((6)A1 → (4)A1), for Mn(2+) decreases by Δ = 1100 cm(-1), while Δ < 100 cm(-1) for the energy E((2)E →( 4)A2) corresponding to Cr(3+). The origin of this surprising difference in these model systems is clarified by writing the transition energies of MF6 complexes through the ten Coulomb and exchange integrals consistent with the cubic symmetry and not considered in the usual Tanabe-Sugano approach. It is shown that E((6)A1 → (4)A1) depends on exchange integrals K(3z(2) - r(2), xy) and K(x(2) - y(2), xy), while E((2)E → (4)A2) depends on K(xz, yz) where the two involved electrons display a π character. These exchange integrals have been calculated just considering a MF6 unit subject to the internal electric field due to the rest of the lattice ions. In addition to a reasonably reproduction of the main trends observed experimentally for the model systems, the present calculations prove that the exchange integrals are not related in a simple way to the covalency of involved orbitals. Particular attention is also paid to explain why the transitions, which are 10Dq-independent are less sensitive to the host lattice change than those which do depend on 10Dq. The present work shows that K(xz, yz) for Cr(3+) is particularly insensitive to the host lattice change and thus sheds light on the origin of the near independence of E((2)E → (4)A2) along the series of oxides doped with such an impurity .
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Affiliation(s)
- J M García-Lastra
- Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark , DK-2800 Kongens Lyngby, Denmark
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Aramburu JA, García-Fernández P, García-Lastra JM, Barriuso MT, Moreno M. Colour due to Cr3+ ions in oxides: a study of the model system MgO:Cr3+. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:175501. [PMID: 23552342 DOI: 10.1088/0953-8984/25/17/175501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Seeking to understand why the cubic centre in MgO:Cr(3+) has the same 10Dq value as emerald, ab initio cluster and periodic supercell calculations have been performed. It is found that the equilibrium Cr(3+)-O(2-) distance, R, in MgO:Cr(3+) is equal to 2.03 Å and thus 0.06 Å higher than that measured for the emerald. Calculations carried out on the isolated CrO(6)(9-) complex at R = 2.03 Å give 10Dq = 14,510 cm(-1), which is 10% smaller than the experimental figure for MgO:Cr(3+). Nevertheless, when the internal electric field, ER(r), due to the rest of the lattice ions is also taken into account, the calculated 10Dq = 16,210 cm(-1) coincides with the experimental value. Accordingly, the colour shift for different oxides doped with Cr(3+) can be well understood on the basis of this extrinsic contribution to 10Dq usually ignored in a ligand field description. The calculated electrostatic potential, VR(r), related to ER(r), is found to be attractive when the electronic density is lying along <110> directions and |r| > 1 Å driven by the first shell of twelve Mg(2+) ions. The action of VR(r) upon the CrO(6)(9-) complex slightly decreases the energy of t2g(xy,xz,yz) orbitals with respect to that for eg(3z(2) - r(2),x(2) - y(2)) orbitals, thus enhancing the 10Dq value by 0.2 eV. However, the addition of VR(r) induces very small changes in the electronic density, a relevant fact that is related to the (2)E(t(2g)(3)) −> (4)A(2)(t(2g)(3)) emission energy being nearly independent of the host lattice along the series of Cr(3+)-doped oxides.
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Affiliation(s)
- J A Aramburu
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Avenida de los Castros s/n, E-39005 Santander, Spain
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10
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Trueba A, García-Lastra JM, Garcia-Fernandez P, Aramburu JA, Barriuso MT, Moreno M. Cr3+-doped fluorides and oxides: role of internal fields and limitations of the Tanabe-Sugano approach. J Phys Chem A 2011; 115:13399-406. [PMID: 21981751 DOI: 10.1021/jp207249w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This work is aimed at clarifying the changes on optical spectra of Cr(3+) impurities due to either a host lattice variation or a hydrostatic pressure, which can hardly be understood by means of the usual Tanabe-Sugano (TS) approach assuming that the Racah parameter, B, grows when covalency decreases. For achieving this goal, the optical properties of Cr(3+)-doped LiBaF(3) and KMgF(3) model systems have been explored by means of high level ab initio calculations on CrF(6)(3-) units subject to the electric field, E(R)(r), created by the rest of the lattice ions. These calculations, which reproduce available experimental data, indicate that the energy, E((2)E), of the (2)E(t(2g)(3)) → (4)A(2)(t(2g)(3)) emission transition is nearly independent of the host lattice. By contrast, the energy difference corresponding to (4)A(2)(t(2g)(3)) → (4)T(1)(t(2g)(2)e(g)(1)) and (4)A(2)(t(2g)(3)) → (4)T(2)(t(2g)(2)e(g)(1)) excitations, Δ((4)T(1); (4)T(2)), is shown to increase on passing from the normal to the inverted perovskite host lattice despite the increase in covalency, a fact which cannot be accounted for through the usual TS model. Similarly, when the Cr(3+)-F(-) distance, R, is reduced both Δ((4)T(1); (4)T(2)) and the covalency are found to increase. By analyzing the limitations of the usual model, we found surprising results that are shown to arise from the deformation of both 3d(Cr) and ligand orbitals in the antibonding e(g) orbital, which has a σ character and is more extended than the π t(2g) orbital. By contrast, because of the higher stiffness of the t(2g) orbital, the dependence of E((2)E) with R basically follows the corresponding variation of covalency in that level. Bearing in mind the similarities of the optical properties displayed by Cr(3+) impurities in oxides and fluorides, the present results can be useful for understanding experimental data on Cr(3+)-based gemstones where the local symmetry is lower than cubic.
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Affiliation(s)
- A Trueba
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Santander, Spain
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11
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Dera P, Lavina B, Meng Y, Prakapenka VB. Structural and electronic evolution of Cr2O3 on compression to 55GPa. J SOLID STATE CHEM 2011. [DOI: 10.1016/j.jssc.2011.09.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Trueba A, Garcia-Fernandez P, García-Lastra J, Aramburu J, Barriuso M, Moreno M. Transition metal impurities in fluorides: Role of electronic structure of fluorine on spectroscopic properties. J Fluor Chem 2011. [DOI: 10.1016/j.jfluchem.2011.05.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Trueba A, Garcia-Fernandez P, García-Lastra JM, Aramburu JA, Barriuso MT, Moreno M. Spectrochemical series and the dependence of Racah and 10 Dq parameters on the metal-ligand distance: microscopic origin. J Phys Chem A 2011; 115:1423-32. [PMID: 21294536 DOI: 10.1021/jp110586e] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The origin of the spectrochemical series and the different dependence of crystal-field splitting (10Dq) and Racah parameters on the metal-ligand distance, R, is explored through ab initio calculations on Cr(3+)-doped K2NaScF6, Cs2NaYCl6, Cs2NaYBr6, and Cs2NaYI6 lattices. For this purpose both periodic and cluster calculations have been performed. An analysis of ab initio results proves that 10Dq values mostly come from the small admixture of deep nLs ligand orbitals present in the antibonding eg(∼ x(2)-y(2),3z(2)-r(2)) level and not from the dominant covalency with valence nLp ligand orbitals, which is actually responsible for the reduction of Racah parameters. This study thus reveals the microscopic origin of the stronger dependence upon R of 10Dq when compared to that observed for Racah parameters, thus explaining why electronic transitions which are 10Dq-independent give rise to sharp optical bands. As a salient feature, while the covalency with nLp levels increases significantly on passing from CrF6(3-) to CrI6(3-), the nLs admixture in eg is found to be practically unmodified. This fact helps to understand the progressive decrease of 10Dq through the series of CrF6(3-), CrCl6(3-), CrBr6(3-), and CrI6(3-) complexes embedded in the corresponding host lattices when compared at the corresponding equilibrium distance at zero pressure. The growing importance of the nLs admixture is well-depicted using deformation density diagrams on passing from the ground state (4)A2(t2g(3)) to the (4)T2(t2g(2)eg) excited state depicted at several R values.
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Affiliation(s)
- A Trueba
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria , Avenida de los Castros s/n, 39005 Santander, Spain
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García-Lastra JM, Moreno M, Barriuso MT. Pressure effects on CrCl63− embedded in cubic Cs2NaMCl6 (M=Sc,Y) lattices: Study through periodic and cluster calculations. J Chem Phys 2008; 128:144708. [DOI: 10.1063/1.2894546] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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García-Fernández P, García-Lastra J, Aramburu J, Barriuso M, Moreno M. Strong dependence of 10Dq on the metal–ligand distance: Key role played by the s–p hybridization on ligands. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.05.101] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Moreno M, Barriuso MT, Aramburu JA, García-Fernández P, García-Lastra JM. Microscopic insight into properties and electronic instabilities of impurities in cubic and lower symmetry insulators: the influence of pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:R315-R360. [PMID: 21690765 DOI: 10.1088/0953-8984/18/17/r01] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This article reviews the microscopic origin of properties due to transition-metal (TM) impurities, M, in insulator materials. Particular attention is paid to the influence of pressure upon impurity properties. Basic concepts such as the electronic localization in an MX(N) complex, the electrostatic potential, V(R), arising from the rest of the lattice ions or the elastic coupling of the complex to the host lattice are initially exposed. The dependence of optical and magnetic parameters on the impurity-ligand distance, R, in cubic lattices is discussed in a first step. Emphasis is put on the actual origin of the R dependence of 10Dq. Examples revealing that laws for strict cubic symmetry cannot in general be transferred to lower symmetries are later given. This relevant fact is shown to come from allowed hybridizations like nd-(n+1)s as well as the influence of V(R). As a salient feature the different colour in ruby and emerald is stressed to arise from distinct V(R) potentials in Al(2)O(3) and Be(3)Si(6)Al(2)O(18). The last part of this review deals with electronic instabilities. The phenomena associated with the Jahn-Teller (JT) effect in cubic lattices, the origin of the energy barrier among equivalent minima and the existence of coherent tunnelling in systems like MgO:Cu(2+) are discussed. An increase of elastic coupling is pointed out to favour a transition from an elongated to a compressed equilibrium conformation. Interestingly the equilibrium geometry of JT ions in non-cubic lattices is shown to be controlled by mechanisms different to those in cubic systems, V(R) playing again a key role. The relevance of first principles calculations for clarifying the subtle mechanisms behind off-centre instabilities is also pointed out. Examples concern monovalent and divalent TM impurities in lattices with the CaF(2) structure. The instability due to the transition from the ground to an excited state is finally considered. For complexes with significant elastic coupling vibrational frequencies and the Stokes shift are expected to undergo bigger changes through a chemical rather than a hydrostatic pressure. The reduction of Huang-Rhys factors upon increasing the pressure is discussed as well.
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Affiliation(s)
- M Moreno
- Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, 39005 Santander, Spain
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Wenger OS, Salley GM, Güdel HU. Effects of High Pressure on the Luminescence and Upconversion Properties of Ti2+-Doped NaCl. J Phys Chem B 2002. [DOI: 10.1021/jp021140t] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Oliver S. Wenger
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland
| | - G. Mackay Salley
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland
| | - Hans U. Güdel
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland
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Wenger OS, Valiente R, Güdel HU. Influence of hydrostatic pressure on the Jahn–Teller effect in the 4T2g excited state of CrCl63− doped Cs2NaScCl6. J Chem Phys 2001. [DOI: 10.1063/1.1387038] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Bray KL. High Pressure Probes of Electronic Structure and Luminescence Properties of Transition Metal and Lanthanide Systems. TRANSITION METAL AND RARE EARTH COMPOUNDS 2001. [DOI: 10.1007/3-540-44447-5_1] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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20
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Riedener T, Shen Y, Smith RJ, Bray KL. Pressure induced phase transition and spectroscopy of Mn5+-doped Li3PO4. Chem Phys Lett 2000. [DOI: 10.1016/s0009-2614(00)00386-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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21
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Shen Y, Bray KL. Influence of low-symmetry distortions on the luminescence of Cr4+-doped forsterite. PHYSICAL REVIEW LETTERS 2000; 84:3990-3993. [PMID: 11019257 DOI: 10.1103/physrevlett.84.3990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/1999] [Indexed: 05/23/2023]
Abstract
By using pressure to vary the extent of nontetrahedral distortions of the Cr4+ site in Mg2SiO4, we reveal the important influence of the 3T1 state on the emission properties of the 3T2 state. We find that 3T1-3T2 mixing has a pronounced effect on the line shape and radiative decay rate of emission from the 3T2 state and that the extent of mixing depends critically on the magnitude of nontetrahedral distortions. The results provide an explanation for the wide variation of Cr4+ emission properties in different host lattices at ambient pressure and indicate that the tailoring of asymmetric distortions of luminescent centers represents an effective new strategy for tuning the linewidth of spectral transitions.
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Affiliation(s)
- Y Shen
- Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA
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Wissing K, Barriuso MT, Aramburu JA, Moreno M. Optical excitations and coupling constants in FeO42− and CrO44− complexes in oxides: Density functional study. J Chem Phys 1999. [DOI: 10.1063/1.480372] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Aramburu JA, Moreno M, Doclo K, Daul C, Barriuso MT. Crystal-field and charge transfer transitions due to Cr3+ ions in fluorides. J Chem Phys 1999. [DOI: 10.1063/1.478023] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Zhao MG. Microscopic origin of the high-pressure-induced spectral shifts in ruby. J Chem Phys 1998. [DOI: 10.1063/1.477447] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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25
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Zheng WC, Wu SY. Theoretical studies of the temperature dependence of zero-field splitting of Cr3+ centers in ruby. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:1117-1122. [PMID: 9985381 DOI: 10.1103/physrevb.54.1117] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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26
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Lochhead MJ, Bray KL. High-pressure fluorescence line narrowing of Eu(III)-doped sodium disilicate glass. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:15763-15775. [PMID: 9980951 DOI: 10.1103/physrevb.52.15763] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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27
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Hömmerich U, Bray KL. High-pressure laser spectroscopy of Cr3+:Gd3Sc2Ga3O12 and Cr3+:Gd3Ga5O12. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:12133-12141. [PMID: 9977981 DOI: 10.1103/physrevb.51.12133] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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28
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Hömmerich U, Bray KL. Direct observation of anticrossing behavior in a luminescent Cr3+-doped system. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:8595-8598. [PMID: 9977475 DOI: 10.1103/physrevb.51.8595] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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29
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Groh DJ, Pandey R, Recio JM. Embedded-quantum-cluster study of local relaxations and optical properties of Cr3+ in MgO. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:14860-14866. [PMID: 9975830 DOI: 10.1103/physrevb.50.14860] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Rodríguez F, Moreno M. Zero-phonon transitions and the Stokes shift of Mn2+-doped perovskites: Dependence on the metal-ligand distance. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:2760-2765. [PMID: 9976515 DOI: 10.1103/physrevb.50.2760] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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31
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Dong-ping M, Xiao-yi H, Ju-rong C, Yan-young L, Ji-ping Z. Calculations of R-line thermal shift of MgO:V2+. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:14067-14071. [PMID: 10007817 DOI: 10.1103/physrevb.48.14067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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32
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Yang L, Xia K. d-orbital theory for an octahedral-site-symmetry crystal and pressure-induced spectral shifts in ruby. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:68-72. [PMID: 10006751 DOI: 10.1103/physrevb.48.68] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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33
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Eggert JH, Moshary F, Evans WJ, Goettel KA, Silvera IF. Ruby at high pressure. III. A pumping scheme for the R lines up to 230 GPa. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:7202-7208. [PMID: 9998628 DOI: 10.1103/physrevb.44.7202] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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