Systematic study of optoelectronic and thermoelectric properties of AHfO₃ (A = Ca, Ba) perovskites at various pressure via ab-initio calculations

Abstract

The physical properties of AHfO₃ (A = Ca, Ba) are revealed using the density functional theory (DFT) based FP-LAPW+lo approach. The existing work investigates the pressure dependence of mechanical, electronic characteristics for specifying the optical and thermoelectric device applications of alkaline rare-earth hafnate perovskites. The PBEsol-GGA functional has been applied for the dealing of the exchange-correlation energy. The lattice constants of the stable cubic phases are extracted by structural optimization, which is similar to the existing experimental and theoretical literature. The bulk moduli (B) and cubic elastic constants are computed for evaluating the mechanical strength against external pressure up to 15 GPa. The electronic properties reveal that Hf-3d states primarily construct conduction band minima, while O–2p states construct valence band maxima at 0 GPa, exhibiting an indirect bandgap (Γ–M), which has been transformed to direct bandgap (Γ–Γ) at 15 GPa. Investigations of the optical properties illustrate that change in pressure can tune the optical parameters of these materials within ultraviolet (UV) energies suggesting commercial optoelectronic utilities. Our analysis shows that BAHfO₃ exhibits better thermoelectric properties than CAHfO₃ at room temperature whereas, thermoelectric performance both the compounds become comparable at a higher temperature.

Graphical abstract