The impact of functionals on BiGaO3 structural, electronic, optical and thermoelectric properties

Abstract

The functionals mBJ-LDA and mBJ-GGA result in high band gaps. BiGaO3 contains covalent bonds due to the mixing of O 2p states with the Bi and Ga s,p states. The Bi breadth PDOS was obviously less in the valence band region compared to Ga and O, with fewer peaks than there were for Ga and consequently Ga-O hybridization is more powerful than Bi-O hybridization. All optical spectra obtained by using mBJ-GGA and EV-GGA approaches have the same profile. At the same energy as the indirect M-X band gap values of 2.24 and 2.56 eV for EV-GGA and mBJ-GGA, the imaginary component reaches non-zero magnitude. The increase in temperature from 300 to 800 K reduces the Seebeck coefficient in BiGaO3 from (3000 to 1500) μV/K. As p-type and n-type ZT have similar values, BiGaO3 has the same thermoelectric efficiency whether it is p-type or n-type.