Helium-nitrogen mixtures at high pressure

The energy landscape of helium-nitrogen mixtures is explored by ab initio evolutionary searches, which predicted several stable helium-nitrogen compounds in the pressure range from 25 to 100 GPa. Among these high-pressure compounds, the monoclinic structure of HeN22 consists of neutral He atoms, partially ionic dimers N-2(delta-), and lanternlike cages N-20(delta-), showing a certain amount of charge transfer within the nitrogen framework. The monoclinic (HeN20)N-delta+(2)delta- may be quenchable to ambient pressure with the estimated energy density of 10.44 kJ/g, which is similar to 2.4 times larger than that of trinitrotoluene, indicating a very promising high-energy-density material.

Automated summary

The energy landscape of helium-nitrogen mixtures has been explored through ab initio evolutionary searches, leading to the prediction of several stable compounds in the pressure range from 25 to 100 GPa. Among these compounds, HeN22 and HeN20 may have high energy densities, making them promising materials for high-energy applications.