The High-Pressure Structural Evolution and Superconductivity of Antiperovskite ZnNNi₃: A Low-Pressure Superconductor

Inspired by recent reports on the diversity of high-pressure structures for perovskites and antiperovskites, we performed a comprehensive investigation of the structural evolution, electronic properties, and superconductivity of antiperovskite ZnNNi3 under pressures ranging from 0 to 120 GPa. The VASP package is employed to fully relax a large number of structures obtained by the CALYPSO crystal structure searching method and other related references. The calculated results indicate that four stable phases─R3̅m, Pm3̅m, P4/mmm and Pmmm─are successfully predicted. At pressures ranging from 0 to 120 GPa, ZnNNi3 undergoes two reconstructive phase transitions: the first, from the R3̅m phase to the Pm3̅m or P4/mmm phase at 77 GPa, and the second, from the Pm3̅m or P4/mmm phase to the Pmmm phase at 101 GPa. More importantly, analyses of the electronic properties reveal that the R3̅m, Pm3̅m, and P4/mmm phases retain metallicity and exhibit a high density of states at the Fermi level, implying that they may possess good superconducting properties. Subsequently, further superconducting analysis indicates that the superconducting transition temperatures (Tc) of the R3̅m, Pm3̅m, and P4/mmm phases are predicted to be 12.2, 13.5, and 10.6 K at zero pressure, respectively. These values are higher than those reported for Ca3PN and RbPbI3, and the material is relatively easy to synthesize experimentally. These findings underscore the potential of ZnNNi3 as a low-pressure superconductor and provide valuable insights for the future exploration of antiperovskite materials with enhanced superconducting properties.