ATOMISTIC SIMULATION STUDIES OF LIK OFF-CENTER DEFECTS IN KTAO3 .1. ISOLATED DEFECTS

Details of the structures and energies of substitutional lithium ions on the potassium site in KTaO3 have been studied by shell model techni ques in which empirically derived potentials have been used to represe nt the short-range interactions. The lithium ion is found to occupy on e of six equivalent off-centre positions along the (100) directions at a distance of 0.64 angstrom from its on-centre location; pi/2 reorien tational jumps between the equivalent sites are found to have a low ac tivation energy of approximately 120 cm-1. Vibrational and librational energies have been calculated as approximately 175 cm- 1 and approxim ately 130 cm-1, respectively.