Theoretical studies of spin-Hamiltonian parameters for Ni2+ ions in CsMgX3 (X=Cl, Br, I) crystals from the two-mechanism model

✍ Scribed by Fang Wang; Wu Xiao-Xuan; Zheng Wen-Chen

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 136 KB
• Volume: 403
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.11.005

✦ Synopsis

In this paper, the high-order perturbation formulas of spin-Hamiltonian (SH) parameters (g factors g J , g ? and zero-field splitting D), including both the crystal-field (CF) and for the first time charge-transfer (CT) mechanisms, are established for 3d 8 ions in trigonal octahedral clusters. By using these formulas, the SH parameters of Ni 2+ ions in CsMgX 3 (X ¼ Cl, Br, I) crystals are calculated. The results are consistent with the experimental values. The calculations suggest that the sign of Q CT (Q ¼ Dg J , Dg ? or D, where the g-shift Dg i ¼ g i Àg e , g e E2.0023 is the value of free-electron) due to CT mechanism is the same as that of the corresponding Q CF due to CF mechanism, and the relative importance of CT mechanism (characterized by Q CT /Q CF ) increases with the increasing atomic number of ligand X. So, for the 3d n ML m clusters with ligand having large atomic number, the reasonable theoretical explanations of all SH parameters should take both CF and CT mechanisms into account. The defect structure of (NiX 6 ) 4À impurity centers in CsMgX 3 :Ni 2+ crystals is also considered in our model.