First principles investigation of structural, elastic, electronic and optical properties of ABi(2)O(6) (A = Mg, Zn) with trirutile-type structure

First principles calculations based on density functional theory with generalized gradient approximation are performed to investigate the structural, elastic, electronic, and optical properties of new bismuth oxides, ABi(2)O(6) (A = Mg, Zn) with the trirutile-type structure. Initially, the geometry structures obtained by geometry optimization are consistent with the experimental values. The calculated structural parameters show a good agreement with the experimental results. The optimized lattice parameters, six independent elastic constants (C-11, C-12, C-13, C-33, C-44 and C-66), bulk modulus (B), shear modulus (G), Young's modulus (Y), Pugh's ratio (G/B), Poisson's ratio (nu), and elastic anisotropy (A) are calculated and discussed. This is the first quantitative theoretical prediction of the electronic, elastic, and optical properties of these compounds. The investigation of the electronic band structures reveals that these compounds are electrical conductors, with contribution predominantly from the Bi 6p states. The analysis of the elastic constants and other moduli shows large anisotropy on elasticity and brittle behavior. The origins of features that appear in different optical properties of these two compounds have been discussed using band structures. The large reflectivity of the predicted compounds in the low energy region might be helpful in high-quality candidate materials for coating to avoid solar heating.