Computer simulations of defects in perovskite KNbO3 crystals

TL;DR

This paper uses ab initio and semi-empirical methods to simulate point defects in KNbO3 crystals, predicting the existence of polarons with specific absorption energies and comparing results with experimental data.

Contribution

It introduces combined ab initio and semi-empirical simulations to analyze defects and polarons in KNbO3, providing new insights into their absorption properties.

Findings

Prediction of one-site and two-site polarons with ~1 eV absorption energies

Identification of defect types in KNbO3 crystals

Comparison with experimental data supports the theoretical models

Abstract

An ab initio LMTO approach and semi-empirical quantum chemical INDO method have been used for supercell calculations of basic point defects - F-type centers and hole polarons bound to cation vacancy - in partly covalent perovskite KNbO3. We predict the existence of both one-site and two-site (molecular) polarons with close absorption energies (~ 1 eV). The relevant experimental data are discussed and interpreted.