Lithium Pentazolate Synthesized by Laser Heating-Compressed Lithium Azide and Nitrogen

Abstract

Searching for polynitrogen compounds has attracted great attention due to their potential applications as high energy density materials. Here, we report a facile approach to the synthesis of a solid lithium pentazolate (LiN5) compound by compressing lithium azide and molecular nitrogen under high pressure with laser heating. The formation of LiN5 with the crystal structure P21/m-LiN5 was identified according to the appearance of the vibrational modes of N5– rings in Raman spectra and synchrotron X-ray diffraction measurements under high pressure. The LiN5 remains stable down to 18.5 GPa upon decompression. The bond lengths in N5– are between single- and double-bond lengths. This study indicates that the precursor can effectively tune the high-pressure phase of pentazolate, providing us an alternative route to synthesize a polynitrogen compound with a novel structure.