Spin-Hamiltonian parameters, defect model and defect structure for the tetragonal Mo⁵⁺ center in x-ray-irradiated α-ZnMoO₄ crystals

ABSTRACT

The spin-Hamiltonian parameters (g factors g_i, hyperfine structure constants A_i (⁹⁵Mo⁵⁺) and A_i (⁹⁷Mo⁵⁺), i = // and ⊥) assigned to the tetragonal Mo⁵⁺ (4d¹) tetrahedral center in α-ZnMoO₄ crystal caused by a Mo⁶⁺(1) ion trapping an electron after x-ray irradiation are calculated from the high-order perturbation formulas resting on the two-mechanism model. The model takes account of both the effects of crystal-field (CF) mechanism concerning the CF excited states in the CF theory and that of the charge-transfer (CT) mechanism related to CT excited states. The calculated results are reasonably consistent with the experimental values, confirming this assignment (or defect model). The calculations also indicate that the effect of CT mechanism cannot be neglected. The defect structure (particularly, the angular distortion) and signs of constants A_i (⁹⁵Mo⁵⁺) and A_i (⁹⁷Mo⁵⁺) of this Mo⁵⁺ defect center are also decided from the calculations. The outcomes are discussed.

KEYWORDS:

• Electron paramagnetic resonance
• defect model and structure
• ligand-field theory
• Mo⁵⁺
• α-ZnMoO₄

Acknowledgements

This project is supported by the Project of Education Department in Sichuan Province (Grant No. 17ZB0206).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project is supported by the Project of Education Department in Sichuan Province [grant number 17ZB0206].