EPR Study of Gd³⁺–V_M and Gd³⁺–Li⁺ Centres in Several Perovskite Fluorides

Abstract

EPR measurements on Gd³⁺ centres in KCdF₃, RbCdF₃, RbCaF₃, CsCdF₃ and CsCaF₃ for crystals co-doped with Li⁺ ions have been made in the cubic phase of host crystals. In all the crystals spectra for Gd³⁺ centres associated with both cation vacancy (V_M) and Li⁺ ion at the nearest divalent cation site have been observed. The observed parameters b₂⁰ and b₄⁴ in the spin Hamiltonian show various dependences on lattice constant in the series of fluorides with the same divalent (Cd²⁺ or Ca²⁺) or the same monovalent (Cs⁺ or Rb⁺) cation. The differences of the magnitude of b₂⁰ and b₄⁴ for Gd³⁺–Li⁺ centre from that for Gd³⁺–V_M centre in the same host crystal are discussed.