Electron Paramagnetic Resonance of Gd³⁺ Centers in RbCdF₃

Abstract

An EPR investigation of Gd³⁺ in RbCdF₃ has been made over a temperature range 296–77 K. The spectra of two type centers with cubic and ⟨100⟩ tetragonal symmetry have been observed at 296 K. The temperature dependence of the tetragonal spectrum in the [100] field direction evidently shows the presence of the phase transition at about 124 K. The field-direction dependence of the tetragonal center in the (001) plane at 77 K indicates conclusively that the Gd³⁺ ion substitutes for a Cd²⁺ site and the charge compensator along the [100] direction should be its nearest neighbor Cd²⁺ vacancy. The results of the temperature and field-direction dependence are discussed qualitatively by the change of the crystal field caused by the phase transition.