First Principles Studies of KNbO$_3$, KTaO$_3$ and LiTaO$_3$ Solid Solutions

TL;DR

This study uses first-principles calculations to explore the physical properties of KTaO3-based solid solutions, revealing insights into Li displacements, potential barriers, and dynamical charge variations related to local electronic dielectric effects.

Contribution

It provides detailed first-principles insights into the atomic displacements and charge dynamics in KTaO3 solid solutions, aligning with experimental data and explaining local dielectric heterogeneity.

Findings

Li displacements and barrier heights match experimental data

Dramatic changes in B-site dynamical charges observed

Local dielectric heterogeneity explains charge variations

Abstract

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.