Stability, elastic anisotropy, and electronic properties of Ca2C3**Project supported by the National Natural Science Foundation of China (Grant Nos. 11204007 and 61474089), the Natural Science Basic Research Plan in Shaanxi Province, China (Grant Nos. 2016JM1026 and 2016JM1016), and the Natural Science Foundation from Education Committee of Shaanxi Province, China (Grant Nos. 16JK1049 and 16JK1016).

Abstract

The systematic investigations of the mechanical, elastic, and electronic properties, and stability of the newly synthesized monoclinic C2/m-Ca2C3 are performed, based on the first-principles calculations. Ca2C3 is found to be mechanically and dynamically stable only from 0 GPa to 24 GPa. The elastic anisotropy studies show that Ca2C3 exhibits the elastic anisotropy increasing with the augment of pressure. Furthermore, using the HSE06 hybrid functional, the electronic properties of Ca2C3 under pressure are calculated. The structure can be regarded as a quasi-direct band gap semiconductor, and the pressure-induced direct-indirect band gap transition is studied in detail.