Phase Stability, Electronic, and Optical Properties in Pcca, R3c, and Pm-3m Phases of BiGaO3 Perovskite

Using generalized gradient approximation (GGA) and local density approximation (LDA), the phase stability, electronic, and optical characteristics of BiGaO3 in the Pcca, R3c, and Pm-3m phases are examined. The structural phase transition can be caused by the few soft modes between F and Z points in the R3c phase. Because it is coupled to isotropic deformation, the bulk modulus of BiGaO3 is an indicator of its high hardness. When electrons travel from the top of the valence band (O-2p) to the bottom of the conduction band (Ga-4p or Bi-6p), optical transitions are detected. The pyroxene Pcca phase of BiGaO3 is the most stable, according to GGA-Perdew-Burke-Ernzerhof (PBE) total energy calculations. At 5 GPa, the phase change from the Pcca to the R3c structure occurs. Because of the smaller reticular lengths and higher Coulomb forces, the elastic constants of BiGaO3 are quite significant.