Structural and Optoelectronic Properties of Cubic Perovskite Type XAlO₃ (X = Gd and Dy) Theoretical Investigation

In this paper, we have performed a theoretical study using the linear augmented and linearized plane wave method (FP-LAPW) implemented in the Wien2k computational code based on density functional theory (DFT) to determine the structural, electronic and optical properties of GdAlO₃ and DyAlO₃ perovskites. The exchange and correlation potential are treated by the generalized gradient approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and modified Becke-Johnson potential (mBJ). The structural properties such as lattice parameter, modulus of compressibility and its derivative are in good agreement with other theoretical results.

The electronic properties, such as band structure and density of state revealed an indirect energy gap in the L - xG direction for GdAlO₃, with gap values of 2.879 eV (GGA-PBE), 5.006 eV (mBJ) in spin-up and 2.286 eV (mBJ), 2.736 eV (mBJ) in spin-dn.for DyAlO₃ perovskite, due to the over lap of the valence and conduction bands at Fermi level, which behaves like a metal oxide.

We have also calculated the optical properties of these two compounds, such as dielectric function, refractive index, absorption coefficient and optical conductivity. They indicate that GdAlO₃ and DyAlO₃ perovskites could be useful for applications in UV photo catalysis.