Structural, electronic, and optical properties of α, β, and γ-TeO2

First-principles calculations of the structural, electronic, and optical properties of TeO2 polymorphs were performed with the density functional theory plane-wave pseudopotential method. The results reveal that all the three crystalline TeO2 phases are wide-gap semiconductors and the lone electron pairs have contributions near the Fermi energy level. The layer structure of β-TeO2 leads to the obvious anisotropy of the complex dielectric function. Considering the lattice contribution of dielectric constants, we predict the static dielectric constants of TeO2 polymorphs. For α-TeO2, the calculated values of 19.0 for ε1⊥ and 25.3 for ε1∥ agree well with the experimental value, and the β- and γ-phases also belong to the high dielectric constant materials. Besides, a special collective plasma resonance for γ-TeO2 has been found in lower energy. It corresponds to the small peak in the imaginary part of dielectric function, and reflects the abrupt reduction in the reflectivity spectrum.