First-Principles Study of Geometric and Electronic Structures of Rare Earth- and Transition Metal-Based Perovskite Oxides

Abstract

The perovskite oxides the general formula of ABO3 have many excellent physical properties including multiferroic effects catalytic activity electrochemical properties and related transport properties making them popular materials for engineering applications In this work we investigate the geometric and electronic structures of rare-earth and transition-metal perovskite oxides La(Mn Co Cr Fe Ni)O3 and Gd(Fe0 8Ni0 2)O3 based on first-principles calculations La (Mn Co Cr Fe Ni)O3 known as “high entropy oxides” contain 5 elements on the b-site sublattice of the perovskite structure which are thermodynamically stable after structure relaxation Upon substitution of Ni at the b-site to certain concentrations in La(Mn Co Cr Fe Ni)O3 no band gap exists in the system From PDOS analysis we observe hybridization between d orbitals of transition metals especially from Mn and Ni and p orbitals of oxygens From Bader-charge analysis charges of each element in La(Mn Co Cr Fe Ni)O3 are similar as charges of elements in the parent perovskites LaMnO3 LaCoO3 LaCrO3 LaFeO3 and LaNiO3 It shows that each b-site in perovskite high-entropy oxides is nearly equivalent For Gd(Fe0 8Ni0 2)O3 the calculated results show that substituting Ni for Fe in the b-site of GdFeO3 band gap 1 97~2 08 eV makes the system conducts with spin polarization and magnetism Besides the magnetism mostly comes from f orbitals of Gd

Date of Award	2019
Original language	English
Supervisor	Yen-Hsun Su (Supervisor)