Pressure-Induced High-Energy-Density BeN4 Materials with Nitrogen Chains: First-Principles Study

• Published in: Journal of physical chemistry. C 2021-11, Vol.125 (46), p.25376-25382
• Main Authors: Zhang, Xunjiang, Xie, Xing, Dong, Huafeng, Zhang, Xin, Wu, Fugen, Mu, Zhongfei, Wen, Minru
• Format: Article
• Language: English
• Subjects: C: Energy Conversion and Storage
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.1c07500

The search for high-energy-density materials (HEDMs) using polymeric nitrogen has attracted widespread attention in recent years. However, it is very difficult to synthesize polymeric nitrogen due to the rigorous requirements of extremely high temperature and pressure. Previous theoretical predictions and experiments have shown that the addition of alkaline earth metals as cationic ligands can stabilize the polymerization structure of nitrogen and reduce the synthesis pressure. Using the USPEX structure prediction code and first-principles calculations, two novel BeN4 structures with extended nitrogen chains have been discovered (i.e., γ-BeN4 and δ-BeN4) in this work. An enthalpy study reveals that γ-BeN4 is the most stable structure under environmental pressure, while γ-BeN4 is a metastable structure in the pressure range of 0–120 GPa, and they can be synthesized under pressures of 20.8 and 27.4 GPa, respectively (lower than the 28.5 GPa required for P 21/ c -BeN4). Furthermore, γ-BeN4 and δ-BeN4 have high energy densities of 3.1 and 4.7 kJ/g, respectively, showing that these nitrogen salts are potential HEDMs.