Structural, mechanical, electronic, optical and thermodynamic features of lead free oxide perovskites AMnO3 (A=Ca, Sr, Ba): DFT simulation based comparative study

Abstract

Perovskite oxides with transition metals have been subjected to a lot of concern in the recent time having their exclusive physical and chemical property. Due to ferroelectric character these types of materials have huge technological applications in worldwide. In the existing project, the crystal structure stability, single and polycrystalline bulk properties, electron-charge density, photon and temperature related optical as well as thermal features of perovskite oxides AMnO3 (A = Ca, Sr, Ba) have been investigated through DFT simulation with CASTEP code. Very good accordance in the investigated and synthesized lattice parameters is found. Mechanical stabilities of phases AMnO3 (A = Ca, Sr, Ba) are ensured from the investigated elastic stiffness constants. Ductile nature of compounds AMnO3 (A = Ca, Sr, Ba) are ensured from the study of Pugh's and Poisson's ratios. Hardness calculations ensured that all the studied materials are hard in nature where SrMnO3 has little bit higher hardness nature compared to others. Very high machinability index of CaMnO3 confirmed its suitable industrial application compared to the rest two compounds. Anisotropic character of AMnO3 (A = Ca, Sr, Ba) is observed from the analysis of elastic anisotropy factor. Band structure calculations with up-spin and down-spin reveal the metallic and semi-metallic nature of AMnO3 (A = Ca, Sr, Ba) respectively. Ionic and covalent bonded nature of AMnO3 (A = Ca, Sr, Ba) are confirmed from the Mulliken atomic population and charge density calculations. Very high absorption and conductivity of AMnO3 (A = Ca, Sr, Ba) have been observed in the ultraviolet energy site which ensure their possible applications in optical devices operates at UV energy regions. The dielectric function make sure the metallic nature of AMnO3 (A = Ca, Sr, Ba) as the actual value approaches to zero from negative energy region. Comparatively high Debye temperature of AMnO3 (A = Ca, Sr, Ba) revealed that these compounds are thermally more conductive where CaMnO3 is more conductive than the rest two materials. Very low value of Kmin of material BaMnO3 ensured that this phase has more possibility to use in thermal barrier coating materials (TBC) than CaMnO3 and SrMnO3 materials.