Structural Electronic and Mechanical Properties of Perovskites

Abstract

This thesis deals with the study of STRUCTURAL, ELECTRONIC AND MECHANICAL PROPERITES OF PERVOSKITES. The electronic and structural properties of transition-metal oxides are a continuing research theme due to the variety of ground states and their technological applications. In present study, the first-principles calculations are performed using the full-potential linear augmented plane-wave methods (FP-LAPW) on the structural, electronic, optical and mechanical properties of the cubic (Pm 3m space group) perovskite oxides such as BaPaO3, BaUO3, CsCaCl3 and KCdF3. The current study is given within the density-functional theory (DFT) basis. The exchange-correlation potential is introduced by different approaches including local density approximation (LDA), general gradient approximation (GGA) and modified Becke Johnson (mBJ) exchange potential. We computed the equilibrium lattices, bulk modulus and its pressure derivatives and equilibrium volume. Our obtained results agree successfully with the theoretical and experimental data available. We discuss an extensive set of results obtained by using WEIN 2K code is based on solving the Kohn Sham equations by using the full potential linearized-augmented plane wave (FP-LAPW) method. The method has enabled us to obtain accurate results on a range of systems, particularly in compounds containing strongly correlated ions, such as BaPaO3, BaUO3, CsCaCl3 and KCdF3. This is possible because The Kohn Sham equations were solved by applying the full-potential linearized augmented-plane-wave (FP-LAPW) method. The compounds investigated include two families of perovskite-structured oxides, of potential interest for technological applications due to their high melting points, chemical and mechanical stability in a wide range of temperature. The latter materials exhibit simultaneously their simple crystal structures and unique ferroelectric piezoelectric and dielectric properties, which is however highly desirable for fuel cells, hydrogen sensors, photoelectric devices and radiation detector applications. newline