Li Qiuyue, Yang Qiuping, Han Shuai, Li Fei, Yao Yansun, Yang Guochun
State Key Laboratory of Metastable Materials Science & Technology and Hebei Key Laboratory of Microstructural Material Physics, School of Science, Yanshan University, Qinhuangdao, 066004, China.
Key Laboratory of Materials Modification by Laser, Ministry of Education, Ion and Electron Beams (Dalian University of Technology), Dalian, 116024, China.
Chemphyschem. 2025 May 19;26(10):e202401150. doi: 10.1002/cphc.202401150. Epub 2025 Mar 6.
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: NaN, NaN, and NaN. Notably, the electride NaN undergoes a pressure-induced structural transition from a P6/mmm to a P6/mmc phase. This transformation is characterized by spatial reorientation and redistribution of interstitial anionic electrons (IAEs). In the P6/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, P6/mmc phase undergoes a transition from metallic to semiconducting behavior due to the increased interaction between sodium and IAEs. Additionally, C2/m NaN, 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.
通过第一性原理结构搜索计算，我们研究了高压下钠氮（Na-N）化合物的相稳定性。我们的研究表明，压力增加促进了富钠氮化物的形成，从而预测出三种先前未报道的化学计量比：NaN、NaN和NaN。值得注意的是，电子化合物NaN经历了由压力诱导的从P6/mmm到P6/mmc相的结构转变。这种转变的特征是间隙阴离子电子（IAEs）的空间重新定向和重新分布。在P6/mmc相中，IAEs采用零维、类似三角形的构型，而在低压P6/mmm相中，它们形成相互连接的、类似石墨烯的网络。随着压力增加，由于钠与IAEs之间相互作用增强，P6/mmc相从金属行为转变为半导体行为。此外，具有三角形和船形IAEs的C2/m NaN预计会表现出超导性。我们的研究结果为高压条件下富钠氮化物的行为和稳定性提供了新的见解。
