First principles study on the structures and properties of SnO–ZnO alloys under high pressure

Abstract

SnxZn1-xO alloys are potential candidates to be widely used in photoelectric solar energy conversion, gas sensors and other fields. However, their crystal structures and physical properties have not been systematically studied, which hinders their in-depth investigation. Herein, we used USPEX software package to search for the crystal structures of SnxZn1-xO alloys in the pressure range of 0–60 GPa. A new ground state structure of SnZnO2 (Cmcm) and several other metastable structures of SnxZn1-xO were predicted. Our studies showed that pressure can be an effective method to promote the formation of stable SnO–ZnO alloys. The dynamic and mechanical stabilities of the predicted crystal structures were established by calculating the phonon spectra and elastic properties of the crystals. Finally, the electronic structures and optical properties of SnxZn1-xO system were investigated using the first-principles calculations. The optical absorption coefficient of SnZnO2 as a function of pressure was calculated, and the results showed that the absorption peaks move to higher energy as the pressure increases.