Theoretical study of the local distortions and the EPR parameters for VO2+ and Cu2+ centers in oxyfluoroborate glasses

The local lattice distortion at the trigonal Cr3+ center in BiI3 is theoretically studied by the perturbation formulas of the EPR parameters for a 3d3 ion in trigonal symmetry, based on the cluster approach. In these formulas the contributions from the s-orbitals of the ligands, which were often ignored, are taken into account. It is found that the local angle β (between the direction of the impurityligand bonding R and the C3 axis) in the impurity center is smaller than the host angle βH in the pure crystal. The calculated EPR parameters are improved compared to those in absence of the ligand s-orbital contributions. The local lattice distortion obtained in this work is discussed.

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EPR Theoretical Study of the Local Lattice Structure of Fe3+ Doped in MgTiO3 and LiTaO3

Zeitschrift für Naturforschung A ◽

10.1515/zna-2007-1-214 ◽

2007 ◽

Vol 62 (1-2) ◽

pp. 101-106

Author(s):

Lei-Lei Pan ◽

Xiao-Yu Kuang ◽

Guang-Dong Li ◽

Hui Wang

Keyword(s):

Local Structure ◽

Theoretical Study ◽

Lattice Structure ◽

Ligand Field ◽

Zero Field ◽

Structure Parameters ◽

Spin Orbit Coupling ◽

Local Lattice ◽

Epr Parameters ◽

Epr Experiments

The EPR zero-field splittings of Fe3+ doped in MgTiO3 and LiTaO3 are studied by diagonalizing the complete energy matrices of the electron-electron repulsion, ligand-field and spin-orbit coupling interactions for a d5 configuration ion in a trigonal ligand-field. It is shown that, when Fe3+ is doped in aMgTiO3 or LiTaO3 crystal, the local lattice structure around the octahedral Fe3+ center has an obvious distortion along the C3 axis. By simulating the second- and fourth-order EPR parameters D and (a−F) simultaneously, the local structure parameters of Fe3+ doped inMgTiO3 and LiTaO3 crystals are determined, which reveal that Fe3+ occupies both the Mg2+ and Ti4+ sites in the MgTiO3:Fe3+ system and occupies the Li+ site rather than the Ta5+ site in the LiTaO3:Fe3+ system. The results accord with the ENDOR and EPR experiments. - PACS numbers: 71.70.Gm; 75.30.Et; 71.70.Ch.

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Investigations of the local distortions and EPR parameters for Cu2+in xNa2O-(30-x)K2O-70B2O3(5 ≤ x ≤ 25 mol%) glasses

Magnetic Resonance in Chemistry ◽

10.1002/mrc.4684 ◽

2017 ◽

Vol 56 (3) ◽

pp. 190-195 ◽

Cited By ~ 1

Author(s):

Zhen-Ya Zhang ◽

Shao-Yi Wu ◽

Fu Zhang ◽

Cheng-Xi Zhang ◽

Rui-Jie Qin ◽

...

Keyword(s):

Epr Parameters ◽

Local Distortions

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Studies of the Local Distortions and the EPR Parameters for Cu2+ in xLi2O-(30–x)Na2O-69·5B2O Glasses

Zeitschrift für Naturforschung A ◽

10.1515/zna-2015-0453 ◽

2016 ◽

Vol 71 (3) ◽

pp. 249-254 ◽

Cited By ~ 3

Author(s):

Chang-Chun Ding ◽

Shao-Yi Wu ◽

Min-Quan Kuang ◽

Xian-Fen Hu ◽

Guo-Liang Li

Keyword(s):

Relative Elongation ◽

Sodium Borate ◽

Elongation Ratio ◽

Paramagnetic Resonance ◽

Cubic Field ◽

Mixed Alkali Effect ◽

Jahn Teller ◽

Jahn Teller Effect ◽

Epr Parameters ◽

Local Distortions

AbstractThe local distortions and electron paramagnetic resonance (EPR) parameters for Cu2+ in lithium sodium borate (LNB) glasses xLi2O·(30–x)·Na2O·69.5B2O3 (5≤x≤25 mol%) are theoretically studied at various concentrations x in a consistent way. Owing to the Jahn–Teller effect, the [CuO6]10− clusters are found to experience the significant tetragonal elongations of 16% along C4 axis. Despite the nearly unchanging observed g factors, measured d–d transition band (or cubic field parameter Dq) shows remarkable linear increases with concentration x, whose influences on g‖ and g⊥ are actually cancelled by the linearly increasing covalency factor N and relative elongation ratio η with x. The almost unvarying hyperfine structure constants are attributed to the fact that the influences of the linearly increasing N and the linearly decreasing core polarisation constant κ largely cancel one another. The microscopic mechanisms of the above concentration dependences for these quantities are illustrated from mixed alkali effect (modification of B2O3 network by transforming some BO3 units into BO4 ones with variations in modifier Li2O concentration).

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