Studies of the g factors and the local structure of the orthorhombic Ni⁺ center in KTaO₃ crystal

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• 作者：Hua-Ming Zhang ; ^{huamingzhang66@gmail.com} ; Xiong Wan ; Zhi-Min Zhang
• 关键词：Electron paramagnetic resonance ; Defect structure ; Crystal and ligand fields ; Ni+ ; KTaO3
• 刊名：Physica B
• 出版年：2012
• 期刊代码：53_09214526
• 类别：ph
• 出版时间：15 June, 2012
• 卷：407
• 期：12
• 页码：2201-2204
• 文件大小：154 K

摘要

The local structure and the g factor (g_x, g_y, and g_z) of the Ni⁺ center in KTaO₃ are theoretically studied using the perturbation formulas of the g factors for a 3d⁹ ion in orthorhombically elongated octahedra. The orthorhombic field parameters are determined from the superposition model and the local geometry of the system. In view of the covalency, the contributions from the ligand orbital and spin-orbit coupling interactions are taken into account from the cluster approach. In the calculations, the orthorhombic center is attributed to Ni⁺ occupying the host Ta⁵⁺ site, associated with the nearest-neighboring oxygen vacancy V_O along the c-axis. Furthermore, the planar Ni⁺-O^{2鈭?/sup> bonds are found to experience the relative variation 螖R (鈮?.076 脜) along the a- and b-axis, respectively, due to the Jahn-Teller effect and the size mismatching substitution of Ta5+ by Ni+. Meanwhile, the effectively positive V_O can make the central Ni+ displace away from V_O along the c-axis by about 0.20 脜. The calculated g factors based on the above local distortions show good agreement with the experimental data.}