Novel phase transition for XSnN2 (X = Mg, Zn) under uniaxial compression

The behavior of ternary nitrides MgSnN2 and ZnSnN2 were computationally explored under uniaxial compres-sions in [100] direction. It was found that at 20 GPa MgSnN2 transforms from the Pna21 structure into a Pnma phase, while this new phase can remain with compression fully released. Similar phase transition was observed for ZnSnN2 at 41 GPa, while the high pressure phase will recover to the original lattice when compression is removed. In addition, the band gap increases along with an enhancing compression in the investigated pressure range for MgSnN2, accompanied with a sudden increase at the critical point of the phase transition. While for ZnSnN2, it shows a drop at the phase transition and continues to decrease with even larger compression. The light absorption will basically be suppressed for MgSnN2 and ZnSnN2 in visible and near ultraviolet region under compression, while enhanced at high frequency above 14 eV. Moreover, the metastable Pnma phase of MgSnN2 is studied at ambient conditions and shows promising conductive properties, comparing to the Pna21 structure.

Automated summary

The behavior of ternary nitrides MgSnN2 and ZnSnN2 under compression was computationally explored. Phase transitions were observed for both materials at certain pressures, and the structural recovery differed after compression release. In addition, the band gap of MgSnN2 increased with compression, while the band gap of ZnSnN2 decreased. Light absorption was suppressed under compression but enhanced at high frequencies. The metastable structure of MgSnN2 showed promising conductive properties.