A paramagnetic defect was identified, by using electron paramagnetic resonance techniques, and was attributed to a paramagnetic S = ½ off-centre ion situated near to a Ba site. It was noted that 12 magnetically distinguishable sites contributed to the angular dependence pattern of the spectra, with each of the sites being characterized by an orthorhombic g-tensor. The relative occupations of the sites changed under uniaxial stress. The features of the centre were highly characteristic of the indicated off-centre position; as revealed by a comparison with previously identified Ti3+ near to a Sr2+ site in SrTiO3. On the basis of the principal values of the g-tensor, the paramagnetic ion was identified as being Ni, and it was proposed that +1 was the most likely charge state.

An Off-Center Ion near a Ba Site in BaTiO3 as Studied by EPR under Uniaxial Stress. S.Lenjer, R.Scharfschwerdt, T.W.Kool, O.F.Schirmer: Solid State Communications, 2000, 116[3], 133-6