First-Principles Study on the Crystalline Ga4Sb6Te3 Phase Change Compound

The (Formula presented.) compound on the (Formula presented.) pseudobinary tie-line is proposed in the literature as a phase change material with high crystallization temperature. Herein, the crystal structure of this compound is uncovered by means of a genetic algorithm and electronic structure calculations based on density functional theory. As opposed to the parent GaSb compound which crystallizes in the zincblende structure, the (Formula presented.) compound features an octahedral-like coordination for Ga as well as for Sb and Te atoms. Other structures close in energy to the ground state are also proposed, including some with a tetrahedral-like coordination of Ga atoms. Raman spectra computed within density functional perturbation theory and an empirical Bond Polarizability Model are shown to be able to discriminate among the different possible local environments of Ga atoms.