Effect of inhomogeneous deformation on the electronic structure of SnO₂ and Sn_xSb_1-xO₂ phases

Abstract

The electronic structures of various phases in the Sn–Sb–O₂ system under pressure and under tetragonal, monoclinic, and orthorhombic deformation are studied. Calculations are performed using the first-principles pseudopotential method. It is established that SnO₂ undergoes the following phase transitions under pressure: rutile–pyrite (17 GPa) and pyrite–fluorite (138 GPa). It is also found that doping SnO₂ with Sb leads to a shift of the Fermi level to the conduction band and to additional resonant states below the valence band. Inhomogeneous deformation of Sn_x Sb_1–x O₂, x = 1.00; 0.94; 0.88, at δ ≤ 0.2 causes a stress up to 6.2 GPa, depending on the strain. An analysis of the density of electron states in the bandgap of the deformed structures shows that the gap broadens under tetragonal deformation and narrows under orthorhombic and monoclinic deformation. The theoretical results obtained should be taken into account in interpreting the piezoresistive properties of Sn–Sb–O₂-based thick films.