An electron spin resonance study of vanadium-doped alpha -TeO2single crystals

Abstract

An ESR study of vanadium-doped paratellurite indicates that vanadium enters the lattice as V⁴⁺, equally populating the four inequivalent cation sites. The 3d¹ electron exhibits hyperfine interaction with the I=7/2 ⁵¹V nucleus and superhyperfine interaction with two neighbouring I= 1/2 nuclei identified as protons by ENDOR experiments. Spin Hamiltonian parameters computed from ESR measurements show that each V⁴⁺ ion has a single C₂ symmetry axis along one of the (110) directions. The neighbouring hydrogens appear to enhance the symmetry and stability of the defect structure. Group theoretical arguments show that there are two possible linear combinations of d wavefunctions that could represent the ground state of V⁴⁺ in alpha -TeO₂. However, a determination of the lower-lying state was not feasible using only the ESR data.