Thermodynamic stability and optoelectronic property modulation of KTaO₃ via substitutional doping with Sr, Ba, La and...

In this work, we employ density functional theory (DFT) calculations to investigate the thermodynamics and optoelectronic properties of alkaline-earth (Sr and Ba) and rare-earth (La and Pr) metal dopants when introduced as substitutional defects in KTaO₃. The structural, energetic and thermodynamic stability of the doped systems are examined with SCAN meta-GGA functional. On the other hand, the mBJ-LDA meta-GGA is employed for more accurate description of electronic and optical properties. Our results indicate that Sr, Ba and La dopants preferably substitute at the K-site of KTaO₃. In contrast, Pr doping is thermodynamically more stable at the Ta-site of KTaO₃. While Sr-, Ba- and La-doped systems exhibit electron-doped semiconductor behaviour, their threshold of optical absorption shift towards higher energy UV photons. On the contrary, doping of Pr at a Ta-site of KTaO₃ is found to be stable under oxygen-rich chemical environment and leads to a hole-doped semiconductor behaviour with optical absorption threshold shifted towards the visible region. Owing to growing interest in the properties emerging from doping of alkaline-earth and rare-earth elements in KTaO₃ in recent experiments, the outcomes of this study provide valuable insights into designing materials suitable for photocatalytic applications.