Single crystal EPR study of VO²⁺ in LiCsSO₄

Abstract

A detailed single crystal EPR study of VO²⁺ in LiCsSO₄ (LCS) has been carried out from room temperature down to 133 K. The room temperature EPR analysis indicates that VO²⁺ substitutes for the Cs atom and that there are six magnetically inequivalent Cs⁺ sites. The charge compensation takes place in two different ways. For two of the sites the charge compensation occurs by removal of a neighbouring Cs atom at a distance of ≈4.5 Å; whereas for the other four magnetically inequivalent sites the charge compensation is due to removal of a neighbouring Li atom at a distance of 3.5 Å from it. The single crystal analysis yields the following spin-Hamiltonian parameters at room temperature: g_XX = 1.987 ± 0.002, g_YY = 1.983 ± 0.002, g_ZZ = 1.932 ± 0.002; A_XX = 7.8 ± 0.2 mT, A_YY = 7.4 ± 0.2 mT, A_ZZ = 19.8 ± 0.2 mT. Around 202 K there is a ferroelastic phase transition evidenced by the presence of two chemically inequivalent sites.