Effect of rare earth on physical properties of Na0.5Bi0.5TiO3 system: A density functional theory investigation
Résumé
Na-0.5(Bi3/4RE1/4)(0.5)TiO3 (RENBT, RE = Nd, Gd, Dy, and Ho) compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave (FP-LAPW) method based on the spin-polarized density functional theory implemented in the WIEN2k code. Combined charge density distribution and Ti K-edge X-ray absorption spectra reveal that the RENBT compositions with high polarization values are accompanied by a higher TiO6 distortion, DyNBT, and NdNBT compounds. The effect of the rare-earth elements on the polarization is confirmed experimentally with the collection of the hysteresis loops. The investigation of the electronic properties of the compounds highlights the emergence of a magnetization owing to the 4f orbital effect of the rare-earth elements. Besides, the investigation of the chemical ordering shows a short-range chemical ordering for the pure composition and an increased A-site disorder for dysprosium doped NBT system. The increased disorder may speak for increased relaxor properties in the RE doped compositions. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.