Theoretical prediction of the structure and properties of Sn3N4

First-principles calculations based on plane-wave pseudopotential and local-density approximation (LDA) were carried out to study the structure and properties of Sn3N4. In agreement with experimentally determined crystal structure, γ-Sn3N4, which has a high density, was found to be most energetically favored among the structures considered. We also searched for other possible polymorphs of Sn3N4, which may be stable at higher pressure, by studying the properties of six additional high-pressure structures. Phase transition from the spinel structure to the CaFe2O4 and CaTi2O4-type structures can be expected at pressures of 60GPa and 40GPa, respectively. Sn3N4 is predicted to be a semiconductor with a band gap of 1.15eV within the LDA.