Determination of superposition model parameters required for analysis of the zero-field splitting parameters for Ni2+ ions in NiO6 complexes

Abstract

Superposition model (SPM) analysis of the zero-field splitting parameters (ZFSPs), in short SPM/ZFSP, enables correlation of crystallographic, spectroscopic, and magnetic data for transition ions with an orbitally non-degenerate ground state in crystals. SPM analysis of ZFSPs requires knowledge of the model parameters, i.e. the intrinsic parameters – b ¯ k ( R 0 ) , power law exponents – t k , and the reference distance – R 0 . An extensive survey of literature has revealed that the model parameters for Ni 2+ ( S =1) ions are not available as yet. Hence, in this study we set for determination of the model parameters sets applicable for SPM/ZFSP analysis of Ni 2+ ions in the six-fold coordinated NiO 6 with axial symmetry. Our method utilizes the relationships between the intrinsic parameters b ¯ k ( R 0 ) and the experimental data for the uniaxial-stress parameters obtained for Ni 2+ ions in several crystals. The present results enable modeling of the ZFSP b 2 0 = D for Ni 2+ ( S =1) ions, which hitherto has been hindered by the lack of suitable model parameters sets. Applications of SPM/ZFSP analysis are carried out for Ni 2+ ions doped into α-Al 2 O 3 (corundum), α-LiIO 3 , and LiNbO 3 , as well as the series of fluosilicate crystals with general formula: ABF 6 ·6R 2 O (A=Zn, Mg, Co, Ni, Fe; B=Si, Ti, Sn, BF 4 ; R=H, D). These results will be utilized in studies of Ni 2+ -based systems suitable for pressure sensors in high-pressure electron magnetic resonance (EMR) measurements and spectroscopic properties of Ni 2+ ions in Haldane gap systems. • The superposition model (SPM) parameters for Ni 2+ –O 2− combinations determined. • The applicability of the SPM parameters in the series of fluosilicate crystals analyzed. • Applications of SPM/ZFSP analysis for Ni 2+ in α-Al 2 O 3 , α-LiIO 3 , and LiNbO 3 carried out.