First Principles Studies of KNbO_3, KTaO_3 and LiTaO_3 Solid Solutions

摘要

KTaO_3 -based solid solutions exhibit a variety of interesting physical phenomena. To better understand these phenomena, we performed first-principles calculations on [K_(1-x),Li_x]TaO_3 (KLT) and K[Ta_(1-x),Nb_x]O_3 (KTN) supercells. Our results show Li displacements and potential barrier heights in KLT that are in excellent agreement with values obtained from experimental fits. Dramatic changes in B-site dynamical charges occur in KTN in response to changes in near neighbor (nn) coordination. These effects can be explained by heterogeneity in the local electronic dielectric permittivity.