Novel high-K inverse silver oxide phases of SiO2SiO2, GeO2GeO2, SnO2SnO2, and their alloys

The recently reported inverse silver oxide phase of SiO2SiO2 possesses a high dielectric constant as well as lattice constant compatibility to Si. We explore the closely related oxides, GeO2GeO2, SnO2SnO2 with the same inverse silver oxide structure using ab initio density functional theory within the local density approximation (LDA). According to the phonon dispersion curves, both these structures are computed to be unstable. On the other hand, their alloys Si0.5Ge0.5O2Si0.5Ge0.5O2, Si0.5Sn0.5O2Si0.5Sn0.5O2, and Ge0.5Sn0.5O2Ge0.5Sn0.5O2 are stable with higher dielectric constants than that of SiO2SiO2 in the same phase. Their first-principles elastic constants, electronic band structures and phonon dispersion curves have been obtained with high precision.