Electronic structures and the phase stability of perovskite-type oxides KNbO₃ and KTaO₃

Abstract

Electronic structures of perovskite-type oxides of KNbO₃ and KTaO₃ are calculated for the first time by the band theory based on the self-consistent-charge extended Hückel tight-binding (SCC-XHTB) method including the self-consistent-field (SCF) atomic structure calculations and the scalar relativistic correction. By using the resultant densities of states and the SCC's, the total energies are evaluated for both cubic and tetragonal phases. It is found that the KNbO₃ is stable for the tetragonal phase and the KTaO₃ is stable for the cubic one.

Key Words:

• KNbO₃
• KTaO₃
• SCF
• perovskite-type