Electron Spin Resonance of Cr³⁺ Ions Coupled with Oxygen Vacancies in Rutile

Abstract

Paramagnetic resonance of Cr 3+ spins in TiO 2 single crystals were investigated in detail and two sets of weak absorption signals were observed in addition to usual Cr 3+ resonance lines. By analysing both the directions of the local symmetry axes and the magnitude of spin Hamiltonian parameters D and E of these two groups I and II, it is concluded that these resonances come from substitutional Cr 3+ spins coupled with the second and the third neighbor oxygen vacancies respectively. Spin Hamiltonian parameters determined for each group are given by