Pressure-induced formation of bulk Ge-Sn compounds with high concentration of Sn

Abstract

Bulk Ge-Sn chemical compounds have rarely been synthesized at ambient pressure, due to the low solubility of Sn in Ge. Atomic and electronic structures can be significantly changed by pressure, which holds the promise to synthesize bulk Sn-Ge compounds. Here, we identify the formation of three stoichiometric Ge-Sn compounds (Ge 2 Sn, Ge 3 Sn 2 and Ge 2 Sn 3 ) under high pressure, using the CALYPSO structure prediction method in combination with first-principles calculations. The concentration of Sn (60%) in Ge 2 Sn 3 is higher than that of any synthesized Ge-Sn known compounds. With an increasing Sn concentration, the Ge–Ge bonding patterns of Ge-Sn compounds evolve from infinite 2D-nets (Ge 2 Sn) in turn to rings (Ge 3 Sn 2 ) and then tetramers (Ge 2 Sn 3 ). The calculated electronic band structures show that all the predicted phases are metallic. Our results will pave way for further understanding of the Ge-Sn phase diagram.