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Investigations of the Optical Band Positions and Spin-Hamiltonian Parameters for the Rhombic VO^{2+} Complex in CsCl Crystal

100%

Fang W., Zheng W., Yang D., Tang H.

vol. 125

issue 5

1206-1209

The optical band positions and spin-Hamiltonian parameters (g factors g_{i} and hyperfine structure constants A_{i}, where i=x, y, z) of the rhombic VO^{2+} complex in CsCl crystal are calculated together from two theoretical methods. One is the complete diagonalization (of energy matrix) method and another is the perturbation theory method. The calculated results from the two methods coincide and are in reasonable agreement with the experimental values. So, both methods are effective in the explanations of optical and electron paramagnetic resonance (EPR) data for d^1 ions in crystals. The calculations also suggest that in d^1 rhombic octahedra the ground state is almost a pure | d_{xy} ⟩ state. This point is different from that of conjugate d^9 (e.g., Cu^{2+}) ions in rhombic octahedra where the ground state should be an admixture of ground and first excited states.

Research on the Spin-Hamiltonian Parameters and Local Structure for the Tetragonal Mo^{5+} Centers in CaWO_{4} Crystal

100%

Mei Y., Zheng W., Wei C.

vol. 126

issue 6

1275-1279

The spin-Hamiltonian parameters (g factors g_{∥}, g_{⊥} and hyperfine structure constants A_{∥}(A), A_{⊥}(A), A_{∥}(B) and A_{⊥}(B), A(A) and A(B) belonging to isotopes ^{95}Mo^{5+} and ^{97}Mo^{5+}) of Mo^{5+} ion at the tetragonally-compressed tetrahedral W^{6+} site in CaWO_4 crystal are calculated from the high-order perturbation formulae based on the two-mechanism model, where besides the contributions to spin-Hamiltonian parameters due to the crystal-field mechanism concerning the crystal-field excited states in the extensively-applied crystal-field theory, those due to charge-transfer mechanism concerning charge-transfer excited states (which are omitted in crystal-field theory) are included. The calculated results are in reasonable agreement with the experimental values. The calculations show that for the high-valence state d^{n} ions (e. g., Mo^{5+} considered) in crystals, the contributions due to charge-transfer mechanism should be taken into account in the studies of spin-Hamiltonian parameters. The local structure of Mo^{5+} center in CaWO_4 crystal due to the impurity-induced local lattice relaxation is estimated from the calculations. The results are discussed.

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2 Acta Physica Polonica A

2 2014

2 Zheng W.

1 Fang W.

1 Mei Y.

1 Tang H.

1 Wei C.

1 Yang D.

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Investigations of the Optical Band Positions and Spin-Hamiltonian Parameters for the Rhombic VO^{2+} Complex in CsCl Crystal

Research on the Spin-Hamiltonian Parameters and Local Structure for the Tetragonal Mo^{5+} Centers in CaWO_{4} Crystal