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Koperski M, Vaclavkova D, Watanabe K, Taniguchi T, Novoselov KS, Potemski M. Midgap radiative centers in carbon-enriched hexagonal boron nitride. Proc Natl Acad Sci U S A 2020; 117:13214-13219. [PMID: 32482864 PMCID: PMC7306815 DOI: 10.1073/pnas.2003895117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
When serving as a protection tissue and/or inducing a periodic lateral modulation for/in atomically thin crystals, hexagonal boron nitride (hBN) has revolutionized the research on van der Waals heterostructures. By itself, hBN appears as an emergent wide-bandgap material, which, importantly, can be optically bright in the far-ultraviolet range and which frequently displays midgap defect-related centers of yet-unclear origin, but, interestingly, acting as single-photon emitters. Controlling the hBN doping is of particular interest in view of the possible practical use of this material. Here, we demonstrate that enriching hBN with carbon (C) activates an optical response of this material in the form of a series of well-defined resonances in visible and near-infrared regions, which appear in the luminescence spectra measured under below-bandgap excitation. Two, qualitatively different, C-related radiative centers are identified: One follows the Franck-Condon principle that describes transitions between two defect states with emission/annihilation of optical phonons, and the other shows atomic-like resonances characteristic of intradefect transitions. With a detailed characterization of the energy structure and emission dynamics of these radiative centers, we contribute to the development of controlled doping of hBN with midgap centers.
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Affiliation(s)
- Maciej Koperski
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore;
| | - Diana Vaclavkova
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-Université Paul Sabatier-Institut National des Sciences Appliquées Toulouse-European Magnetic Field Laboratory, 38042 Grenoble, France
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kostya S Novoselov
- Department of Materials Science and Engineering, National University of Singapore, 117575, Singapore;
| | - Marek Potemski
- Laboratoire National des Champs Magnétiques Intenses, CNRS-Université Grenoble Alpes-Université Paul Sabatier-Institut National des Sciences Appliquées Toulouse-European Magnetic Field Laboratory, 38042 Grenoble, France;
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, PL-02-093 Warsaw, Poland
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Optical and magnetic properties of the ground state of Cr 3+ doping ions in REM 3(BO 3) 4 single crystals. Sci Rep 2019; 9:12787. [PMID: 31485006 PMCID: PMC6726637 DOI: 10.1038/s41598-019-49248-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/22/2019] [Indexed: 11/16/2022] Open
Abstract
New data about the state of Cr3+ doping ions in a single crystal of YGa3(BO3)4 have been obtained by studying different methods. Using electron paramagnetic resonance, it was found that the Cr3+ ions substitute the trivalent gallium ions. The obtained spin Hamiltonian parameters of the Cr3+ ions in the YGa3(BO3)4 single crystal (g = 1.9743 ± 0.0004; D = −0.465 ± 0.001 cm−1; E = −0.013 ± 0.001 cm−1) were analyzed and compared with those in TmAl3(BO3)4, EuAl3(BO3)4, and YAl3(BO3)4. The deviation of the Z-axis in the spectrum from the crystallographic axis С3 is 1,7 degrees in YGa3(BO3)4. In situ X-ray diffraction was used to study the structural and elastic properties of huntite-type borates in the temperature range of RT-1073 K. In the radioluminescence (RL) spectra, the Cr3+-related emission bands were observed in the red wavelength range, and the presence of other defect-related bands was also registered in some cases. Thermally stimulated luminescence (TSL) glow curves were acquired over a wide temperature range, and the trap depths of the most prominent bands were calculated. The 11B NMR spectra show that two nonequivalent spectral components exist for BO3 structural elements.
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Nehrkorn J, Veber SL, Zhukas LA, Novikov VV, Nelyubina YV, Voloshin YZ, Holldack K, Stoll S, Schnegg A. Determination of Large Zero-Field Splitting in High-Spin Co(I) Clathrochelates. Inorg Chem 2018; 57:15330-15340. [PMID: 30495930 DOI: 10.1021/acs.inorgchem.8b02670] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joscha Nehrkorn
- Department of Chemistry, Institute for Inorganic and Applied Chemistry, University of Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
- Berlin Joint EPR Laboratory, Institut für Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekuléstr. 5, D-12489 Berlin, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Sergey L. Veber
- International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Institutskaya str. 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova str. 1, 630090 Novosibirsk, Russia
| | - Liudmila A. Zhukas
- International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Institutskaya str. 3a, 630090 Novosibirsk, Russia
- Novosibirsk State University, Pirogova str. 1, 630090 Novosibirsk, Russia
| | - Valentin V. Novikov
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova str. 28, 119991 Moscow, Russia
| | - Yulia V. Nelyubina
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova str. 28, 119991 Moscow, Russia
| | - Yan Z. Voloshin
- Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova str. 28, 119991 Moscow, Russia
| | - Karsten Holldack
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489 Berlin, Germany
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Alexander Schnegg
- Berlin Joint EPR Laboratory, Institut für Nanospektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Kekuléstr. 5, D-12489 Berlin, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
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Escalera-Moreno L, Baldoví JJ, Gaita-Ariño A, Coronado E. Spin states, vibrations and spin relaxation in molecular nanomagnets and spin qubits: a critical perspective. Chem Sci 2018; 9:3265-3275. [PMID: 29780458 PMCID: PMC5935026 DOI: 10.1039/c7sc05464e] [Citation(s) in RCA: 148] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Accepted: 03/07/2018] [Indexed: 12/23/2022] Open
Abstract
Very recently the closely related fields of molecular spin qubits, single ion magnets and single atom magnets have been shaken by unexpected results. We have witnessed a jump in the phase memory times of spin qubits from a few microseconds to almost a millisecond in a vanadium complex, magnetic hysteresis up to 60 K in a dysprosium-based magnetic molecule and magnetic memory up to 30 K in a holmium atom deposited on a surface. With single-molecule magnets being more than two decades old, this rapid improvement in the physical properties is surprising and its explanation deserves urgent attention. The general assumption of focusing uniquely on the energy barrier is clearly insufficient to model magnetic relaxation. Other factors, such as vibrations that couple to spin states, need to be taken into account. In fact, this coupling is currently recognised to be the key factor that accounts for the slow relaxation of magnetisation at higher temperatures. Herein we will present a critical perspective of the recent advances in molecular nanomagnetism towards the goal of integrating spin-phonon interactions into the current computational methodologies of spin relaxation. This presentation will be placed in the context of the well-known models developed in solid state physics, which, as we will explain, are severely limited for molecular systems.
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Affiliation(s)
- Luis Escalera-Moreno
- Instituto de Ciencia Molecular (ICMol) , Univ. de Valencia , C/Catedrático Beltrán 2 , E-46980 Paterna , Spain . ;
| | - José J Baldoví
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149 , D-22761 Hamburg , Germany
| | - Alejandro Gaita-Ariño
- Instituto de Ciencia Molecular (ICMol) , Univ. de Valencia , C/Catedrático Beltrán 2 , E-46980 Paterna , Spain . ;
| | - Eugenio Coronado
- Instituto de Ciencia Molecular (ICMol) , Univ. de Valencia , C/Catedrático Beltrán 2 , E-46980 Paterna , Spain . ;
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Liu C, Mei Y, Chen BW, Liu HG, Zheng WC. Uniform calculation of the optical and EPR spectral data for the trigonal (CrO 6 ) 9− octahedral clusters in Y 3 Al 5 O 12 crystal. Polyhedron 2017. [DOI: 10.1016/j.poly.2017.02.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Mei Y, Zheng WC, Zhang XX. Research of the g factors, optical band positions and local structure for the tetragonal octahedral (CrO 6) 7− clusters in glasses. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1210832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Yang Mei
- School of Mechanical and Electrical Engineering, Mianyang Normal University, Mianyang, P. R. China
| | - Wen-Chen Zheng
- Department of Material Science, Sichuan University, Chengdu, P. R. China
| | - Xin-Xin Zhang
- School of Information Engineering, Mianyang Normal University, Mianyang, P. R. China
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Corzilius B, Michaelis VK, Penzel SA, Ravera E, Smith AA, Luchinat C, Griffin RG. Dynamic nuclear polarization of (1)H, (13)C, and (59)Co in a tris(ethylenediamine)cobalt(III) crystalline lattice doped with Cr(III). J Am Chem Soc 2014; 136:11716-27. [PMID: 25069794 PMCID: PMC4140501 DOI: 10.1021/ja5044374] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The study of inorganic crystalline materials by solid-state NMR spectroscopy is often complicated by the low sensitivity of heavy nuclei. However, these materials often contain or can be prepared with paramagnetic dopants without significantly affecting the structure of the crystalline host. Dynamic nuclear polarization (DNP) is generally capable of enhancing NMR signals by transferring the magnetization of unpaired electrons to the nuclei. Therefore, the NMR sensitivity in these paramagnetically doped crystals might be increased by DNP. In this paper we demonstrate the possibility of efficient DNP transfer in polycrystalline samples of [Co(en)3Cl3]2·NaCl·6H2O (en = ethylenediamine, C2H8N2) doped with Cr(III) in varying concentrations between 0.1 and 3 mol %. We demonstrate that (1)H, (13)C, and (59)Co can be polarized by irradiation of Cr(III) with 140 GHz microwaves at a magnetic field of 5 T. We further explain our findings on the basis of electron paramagnetic resonance spectroscopy of the Cr(III) site and analysis of its temperature-dependent zero-field splitting, as well as the dependence of the DNP enhancement factor on the external magnetic field and microwave power. This first demonstration of DNP transfer from one paramagnetic metal ion to its diamagnetic host metal ion will pave the way for future applications of DNP in paramagnetically doped materials or metalloproteins.
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Affiliation(s)
- Björn Corzilius
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Wu B, Yang W, Liu H, Huang L, Zhao B, Wang C, Xu G, Lin Y. Fluorescence spectra and crystal field analysis of BaMoO(4): Eu(3+) phosphors for white light-emitting diodes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 123:12-17. [PMID: 24384357 DOI: 10.1016/j.saa.2013.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 11/09/2013] [Accepted: 12/04/2013] [Indexed: 06/03/2023]
Abstract
The red phosphors play a vital role in controlling luminous efficiency, color rendering index and adjustability in color temperature of white light emitting diodes (w-LEDs). Here, we demonstrate a type of red-emitting phosphors Eu(3+)-doped barium molybdate phosphors effectively excited by the blue light (464nm). These phosphors present the strong emission spectra around 613nm and their color coordinate values are close to the NTSC standard values. More importantly, by constructing a complete 3003×3003 energy matrix by an effective operator Hamiltonian including the free ion and crystal field interactions, for the first time, the fluorescent mechanism for Eu(3+) ions at the tetragonal (S4) Ba(2+) site of BaMoO(4) crystal were investigated by a complete diagonalization (of energy matrix) method (CMD). The fitting values are close to the experimental results, demonstrating the feasibility of using the complete diagonalization method to study the phosphors for w-LEDs.
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Affiliation(s)
- Bo Wu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science & Technology of China, Chengdu 610054, China
| | - Weiqing Yang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science & Technology of China, Chengdu 610054, China; Department of Optics and Electronics, Chengdu University of Information and Technology, Chengdu 610225, China.
| | - Honggang Liu
- Department of Material Science, Sichuan University, Chengdu 610064, China
| | - Li Huang
- Department of Optics and Electronics, Chengdu University of Information and Technology, Chengdu 610225, China
| | - Bowen Zhao
- Department of Optics and Electronics, Chengdu University of Information and Technology, Chengdu 610225, China
| | - Ce Wang
- Department of Optics and Electronics, Chengdu University of Information and Technology, Chengdu 610225, China
| | - Guoliang Xu
- Department of Optics and Electronics, Chengdu University of Information and Technology, Chengdu 610225, China
| | - Yuan Lin
- State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science & Technology of China, Chengdu 610054, China.
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Wen-Chen Z, Hong-Gang L, Ping S, Yu-Guang Y. Studies of the spin-Hamiltonian parameters and defect structures for the tetragonal and cubic Yb3+ centers in AgCl crystal. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 84:164-167. [PMID: 21964239 DOI: 10.1016/j.saa.2011.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 05/31/2023]
Abstract
The spin-Hamiltonian parameters, g factors and hyperfine structure constants, for the tetragonal and cubic Yb(3+) centers in AgCl crystal are calculated from the complete diagonalization (of energy matrix) method. The calculations are based on the defect models that the tetragonal Yb(3+) center is formed by the substitutional Yb(3+) associated with two nearest Ag(+) vacancy (V(Ag)) along <001> and <001¯> axes (i.e., C(4) axis) owing to charge compensation and in cubic Yb(3+) center the two compensators V(Ag) are remote. From the calculations, the spin-Hamiltonian parameters of both Yb(3+) centers in AgCl are explained reasonably, the signs of hyperfine structure constants A(i)((171)Yb(3+)) and A(i)((173)Yb(3+)) are suggested, the above defect models of both Yb(3+) centers are confirmed and their defect structures are determined.
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Affiliation(s)
- Zheng Wen-Chen
- Department of Material Science, Sichuan University, Chengdu, PR China.
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Kowalczyk RM, Kemp TF, Walker D, Pike KJ, Thomas PA, Kreisel J, Dupree R, Newton ME, Hanna JV, Smith ME. A variable temperature solid-state nuclear magnetic resonance, electron paramagnetic resonance and Raman scattering study of molecular dynamics in ferroelectric fluorides. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:315402. [PMID: 21778562 DOI: 10.1088/0953-8984/23/31/315402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The local nuclear and electronic structures and molecular dynamics of the ferroelectric lattice in selected geometric fluorides (BaMgF(4), BaZnF(4), BaMg(1 - x)Mn(x)F(4) and BaMg(1 - x)Ni(x)F(4); x = 0.001 and 0.005) have been investigated. The (19)F and (25)Mg isotropic chemical shift δ(iso), (25)Mg quadrupolar coupling constants (C(q)) and asymmetry parameters (η) reflect the geometry of the coordination spheres. The zero-field splitting parameters |D| and |E| are consistent with distorted axial symmetry (low temperatures) and nearly rhombic symmetry (high temperatures) of octahedral Mn(2+) coordination. The high resolution of the nuclear magnetic resonance, electron paramagnetic resonance and phonon spectra are consistent with the highly ordered crystallographic structure. Combined multi-technique data evidence the subtle discontinuous changes in the temperature dependences of |D| and |E|, isotropic chemical shifts δ(iso) and signature parameters of Raman bands and suggest a discontinuous structural distortion of the fluoride octahedra. The temperature at which this change occurs depends on the ionic radius of the central ion of the octahedral site and is estimated to be ∼ 300 K for Zn(2+) fluorides and ∼ 240 K for Mg(2+) fluorides. This geometrical distortion modifies the lattice dynamics and originates from the rotation of the fluoride octahedra around a new direction approximately perpendicular to that related to the paraelectric-ferroelectric phase transition.
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Affiliation(s)
- Radoslaw M Kowalczyk
- Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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Zheng WC, Jia GM, He L, Yang WQ. A theoretical study on the temperature dependence of zero-field splitting for the tetragonal Cr3+ center in MgO crystal. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:818-820. [PMID: 21216186 DOI: 10.1016/j.saa.2010.12.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 12/02/2010] [Accepted: 12/11/2010] [Indexed: 05/30/2023]
Abstract
This paper reports a detailed theoretical calculation of the temperature dependence of zero-field splitting D (characterized by ΔD(T)=D(T)-D(0)) for the tetragonal Cr3+ center in MgO crystal by considering both the static contribution due to the thermal expansion of Cr3+ center and the vibrational contribution caused by electron-phonon (including the acoustic and optical phonons) interaction. The vibrational contribution due to the acoustic phonon is calculated using the long-wave approximation similar to the study on the specific heat of crystals and that due to optical phonon is estimated using the single-phonon model. The calculated results are in reasonable agreement with the experimental values. From the calculation, it is found that the static contribution ΔDstat(T) (which is often regarded as very small and is neglected in the previous papers) is larger than the vibrational contribution ΔDvib(T) and so the reasonable studies of temperature dependence of zero-field splitting should take both the static and the vibrational contributions into account.
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Affiliation(s)
- Wen-Chen Zheng
- Department of Material Science, Sichuan University, Chengdu 610064, PR China.
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Wu XX, Zheng WC, Fang W. Theoretical investigations of the EPR parameters for Cr3+ and Mn4+ ions in PbTiO3 crystals. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2008; 69:498-502. [PMID: 17556013 DOI: 10.1016/j.saa.2007.03.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2006] [Accepted: 03/19/2007] [Indexed: 05/15/2023]
Abstract
The complete high-order perturbation formulas of EPR parameters (g factors g( parallel), g( perpendicular) and zero-field splitting D), containing the crystal-field (CF) mechanism and charge-transfer (CT) mechanism (the latter is omitted in crystal-field theory which is often used to study the EPR parameters), are established from a cluster approach for 3d3 ions in tetragonal octahedral sites. According to the calculations based on these formulas, the EPR parameters g( parallel), g( perpendicular) and zero-field splitting D for Cr3+ and Mn4+ ions in PbTiO3 crystals are explained reasonably. The calculations show that (i) the sign of g-shift Deltag(i)(CT) (=g(i)-g(s), where g(s)=2.0023 is free-electron value and i= parallel and perpendicular) in CT mechanism is opposite to, but that of D(CT) is the same as, the corresponding signs in the CF mechanism and (ii) the relative importance of CT mechanism for the high valence state 3d3 ion (e.g., Mn4+) is large and so the contributions to EPR parameters from CT mechanism should be taken into account. The different sign of splitting D and the different defect structure for Cr3+ and Mn4+ impurity centers in PbTiO3 crystals are also suggested from the calculations. The results are discussed.
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Affiliation(s)
- Xiao-Xuan Wu
- Department of Material Science, Sichuan University, Chengdu 610064, People's Republic of China
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Qu GQ, Wu XX, Zheng WC. Investigations of the EPR zero-field splitting and the defect structure for Mn(2+) and Fe(3+) ions in anatase crystals. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 68:905-7. [PMID: 17418632 DOI: 10.1016/j.saa.2006.12.076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 12/11/2006] [Indexed: 05/14/2023]
Abstract
The EPR zero-field splittings D of Mn(2+) and Fe(3+) ions in anatase crystals at room and low temperatures are calculated from the high-order perturbation formula of zero-field splitting D for 3d(5) ions in tetragonal symmetry based on the dominant spin-orbit coupling mechanism. The calculated results are consistent with the observed values. From the calculations, Mn(2+) and Fe(3+) ions are suggested to substitute for Ti(4+) ions in anatase (in the previous paper, Mn(2+) ion was suggested at an interstitial site rather than substitutional site) and the defect structures (characterized mainly by the local oxygen parameter u) for both tetragonal Mn(2+) and Fe(3+) impurity centers are estimated. The different zero-field splitting at room and low temperatures are due mainly to the change of local oxygen parameter u with the temperature. These results are discussed.
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Affiliation(s)
- Gui-Qiang Qu
- Department of Material Science, Sichuan University, Chengdu, PR China
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Wen-Chen Z, Shao-Yi W. Electron paramagnetic resonance parameters of V2+ ions in both Cd2+ sites of CsCdCl3 crystal. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2002; 58:79-82. [PMID: 11808652 DOI: 10.1016/s1386-1425(01)00513-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
From the perturbation formulas based on a two-spin-orbit-parameter model, the electron paramagnetic resonance (EPR) zero-field splitting (D), g-factors (g //, g perpendicular) and hyperfine structure constants (A //, A perpendicular) for V2+ in Cd2+ (I) and Cd2+ (II) sites of CsCdCl3 crystal at room and liquid nitrogen temperatures are calculated. From the calculations, the signs of zero-field splittings and hyperfine structure constants are determined and so all of the EPR parameters are explained reasonably on the basis of the structure data of lattice.
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Affiliation(s)
- Zheng Wen-Chen
- Department of Material Science, Sichuan University, Chengdu, People's Republic of China.
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