Structural and electrical properties of Ga-Te systems under high pressure

First-principles evolutionary calculation was performed to search for all probable stable Ga-Te compounds at extreme pressure. In addition to the well-known structures of P6(3)/mmc and Fm-3m GaTe and 14/m Ga2Te5, several new structures were uncovered at high pressure, namely, orthorhombic 14/mmm GaTe2 and monoclinic C2/m GaTe3, and all the Ga-Te structures stabilize up to a maximum pressure of 80 GPa. The calculation of the electronic energy band indicated that the high-pressure phases of the Ga-Te system are metallic, whereas the low-pressure phases are semiconductors. The electronic localization functions (ELFs) of the Ga-Te system were also calculated to explore the bond characteristics. The results showed that a covalent bond is formed at low pressure, however, this bond disappears at high pressure, and an ionic bond is formed at extreme pressure.