Theory studies of the local lattice distortions and the EPR parameters for Cu2+, Mn2+ and Fe3+ centres in ZnWO4 |
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Authors: | Chang-Chun Ding Shao-Yi Wu Qing-Sheng Zhu Guo-Liang Li Zhi-Hong Zhang Yong-Qiang Xu |
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Institution: | 1. Department of Applied Physics, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, P. R. Chinaccding626@163.com;3. Department of Applied Physics, School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, P. R. China |
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Abstract: | The local lattice distortions and the electron paramagnetic resonance (EPR) parameters (g factors, hyperfine structure constants and zero-field splittings) for Cu2+, Mn2+ and Fe3+ in ZnWO4 are theoretically studied based on the perturbation calculations for rhombically elongated octahedral 3d9 and 3d5 complexes. The impurity centres on Zn2+ sites undergo the local elongations of 0.01, 0.002 and 0.013 Å along the C2 axis and the planar bond angle variations of 8.1°, 8.0° and 8.6° for Cu2+, Mn2+ and Fe3+, respectively, due to the Jahn–Teller effect and size and charge mismatch. In contrast to the host Zn2+ site with obvious axial elongation (~0.31 Å) and perpendicular (angular) rhombic distortion, all the impurity centres demonstrate more regular octahedral due to the above local lattice distortions. The copper centre exhibits significant Jahn–Teller reductions for the spin-orbit coupling and orbital angular momentum interactions, characterised by the Jahn–Teller reduction factor J (≈0.29 ? 1). The calculated EPR parameters agree well with the experimental results. The local structures of the impurity centres are analysed in view of the corresponding lattice distortions. |
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Keywords: | electron paramagnetic resonance (EPR) Cu2+ Mn2+ Fe3+ ZnWO4 |
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