APPLICATION OF THE SUBLATTICE METHOD TO STUDY THE ELECTRONIC STRUCTURE OF LiMO2 OXIDES WITH α-NaFeO2-TYPE STRUCTURE

10.25712/ASTU.1811-1416.2026.02.003

Abstract

This paper presents a comprehensive theoretical study of the structural and electronic properties of LiMO₂ crystals (M = B, Al, Ga, In, Tl) with a trigonal α-NaFeO₂-type structure within the framework of density functional theory (DFT). The equilibrium lattice parameters (a, c) and anion coordinates (z) were determined; for hypothetical crystals (LiBO₂, LiInO₂, LiTlO₂), structural parameters are predicted for the first time. A systematic investigation of the band structure across the entire LiMO₂ series in this structural modification was performed for the first time using the Quantum Espresso software package with various exchange-correlation functionals. A linear decrease in the band gap width was established along the series B→Al→Ga→In→Tl, which accounts for the evolution of electronic properties from dielectrics to semiconductors. Application of the extended sublattice method revealed that the valence band maximum and conduction band minimum are formed predominantly by oxygen states with a significant contribution from third-group cations (B, Al, Ga, In, Tl). The obtained data on the possibility of tuning the band gap via isovalent cation substitution, combined with the high structural stability of octahedral coordination polyhedra, indicate the promising potential of LiMO₂ materials with α-NaFeO₂ structure for application as absorber layers in third-generation solar cells and in high-temperature devices.