Electron paramagnetic resonance parameters and local structure for Gd3+ in KY3F10

The electron paramagnetic resonance parameters, zero-field splittings (ZFSs) b₂⁰, b₄⁰, b₄⁴, b₆⁰, b₆⁴ and the g factors for Gd³⁺ on the tetragonal Y³⁺ site in KY₃F₁₀ are theoretically studied from the superposition model for the ZFSs and the approximation formula for the g factor containing the admixture of the ground ⁸S_7/2 and the excited ⁶L_7/2 (L=P, D, F, G) states via the spin-orbit coupling interactions, respectively. By analysing the above ZFSs, the local structure information for the impurity Gd³⁺ is obtained, i.e., the impurity-ligand bonding angles related to the four-fold (C₄) axis for the impurity Gd³⁺ center are found to be about 0.6° larger than those for the host Y³⁺ site in KY₃F₁₀. The calculated ZFSs based on the above angular distortion as well as the g factors are in reasonable agreement with the observed values. The present studies on the ZFSs and the local structure would be helpful to understand the optical and magnetic properties of this material with Gd dopants.