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 (T_c) 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.