Prediction of Thermodynamically Stable Compounds of the Sc-N System under High Pressure.

Materials under high pressure often exhibit unusual physical and chemical behaviors. We investigated the Sc-N system under high pressure in the range of 0-110 GPa using variable-composition methodology implemented in Universal Structure Predictor: Evolutionary Xtallograpgy (USPEX) in conjunction with Vienna Ab Initio Simulation Package (VASP). The calculation led to prediction of new thermodynamically stable compounds, Sc4N3, Sc8N7, ScN3, and ScN5, and also phase transition of ScN5 from triclinic to monoclinic at 104 GPa. These results are important to understand the structure of Sc-N compounds under high pressure and their elastic and electronic properties.