Abstract Using first‐principles structure search calculations, we investigated the phase stability of sodium‐nitrogen (Na−N) compounds under high pressure. Our study reveals that increasing pressure promotes the formation of Na‐rich nitrides,… Click to show full abstract
Abstract Using first‐principles structure search calculations, we investigated the phase stability of sodium‐nitrogen (Na−N) compounds under high pressure. Our study reveals that increasing pressure promotes the formation of Na‐rich nitrides, leading to the prediction of three previously unreported stoichiometries: Na2N, Na5N, and Na8N. Notably, the electride Na5N undergoes a pressure‐induced structural transition from a P6/mmm to a P63/mmc phase. This transformation is characterized by spatial reorientation and redistribution of interstitial anionic electrons (IAEs). In the P63/mmc phase, IAEs adopt a zero‐dimensional, triangular‐like configuration, whereas in the low‐pressure P6/mmm phase, they form an interconnected, graphene‐like network. With increasing pressure, P63/mmc phase undergoes a transition from metallic to semiconducting behavior due to the increased interaction between sodium and IAEs. Additionally, C2/m Na8N, featuring triangular‐ and ship‐like IAEs, is predicted to exhibit superconductivity. Our findings provide new insights into the behavior and stability of Na‐rich nitrides under high‐pressure conditions.
               
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