Pressure stabilized IV-VI compounds and their crystal structures

Abstract

IV-VI group compounds are of interest in various fields of applications related to energy conversion. Properties of materials largely depend on the electronic structures, which are determined by atomic arrangements in crystal lattices and the chemical compositions. External pressure has been shown to be effective in manipulating structural phase transitions and the nature of chemical bonding. New materials that do not exist in ambient conditions may be stabilized or synthesized at high pressure. In this presentation, I will speak about our recent study of IV-VI group compounds under pressures based on combined theoretical and experimental methods. It is known that the most common stoichiometries of IV-VI binary compounds are 1:1 and 1:2 because of the oxidation states. We found that Pb3Te2, which has an unconventional stoichiometry, may be stabilized above 20 GPa. Further electron-phonon coupling calculations show that it has a low-temperature superconducting transition. Additionally, pressure-induced structural phase transitions of GeSe and the related changes of electronic properties will also be discussed.