Atomistic simulation studies of Li_Koff-centre defects in KTaO₃. I. Isolated defects

Abstract

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