Electron spin resonance of Ti3+ in KTa0.9Nb0.1O3

Two types of Ti3+-related centers are identified in KTa0.9Nb0.1O3 by the electron spin resonance. The centers are attributed to Ti3+–VO (oxygen vacancy) and Ti3+–VO–Nb5+, respectively. Both centers have an axial symmetry, and the g-factor values analysis has shown that the 3d1 electron occupies a (3z2–r2) orbital. This ground state corresponds to the lattice relaxation when Ti3+ is shifted towards VO, as it follows from the calculation in the point-ion crystal field approximation. Some recent results of computer modeling of transition-metal ion–oxygen vacancy (Me–VO) type defects in perovskites are discussed as well.