Revealing the Hygroscopic Behavior of Ultrahigh Nitrogen Content Cyclo‐Pentazolate Salts

Abstract

Three representative cyclo‐pentazolate salts including N2H5+N5−, NH3OH+N5− and NH4+N5−, are highly favored for their ultrahigh nitrogen content (80–96%). However, their ambiguous nature has severely restricted the application exploration. Herein, the relationships between humidity and moisture content of salt were established by quantitative analysis. Among the three salts, the hygroscopic ability has the following order: NH3OH+N5−>NH4+N5−>N2H5+N5−. Especially in the range of 40% RH −60% RH, the NH3OH+N5− has a high sensitivity to water, and the absorbed moisture content can be as high as 20.8% at 60% RH. When the relative humidity exceeds 60% RH, the hygroscopic rate of NH3OH+N5− rises sharply, at 80% RH, NH3OH+N5− will absorb excess moisture and turns into liquid form. After treating NH3OH+N5− at 40% RH, the very sensitive friction sensitivity (FS) and impact sensitivity (IS) of dried NH3OH+N5− (FS=20 N, IS=2 J) will change into insensitive salt (FS>360 N, IS>40 J). The higher moisture content in NH3OH+N5−, the lower the thermal stability, its thermal decomposition temperature (103.22°C) is 3.24°C lower than that of dry salt (106.46°C) at 75% RH (moisture content is 30.2%). The other two salts N2H5+N5− and NH4+N5− have the similar properties. Molecular dynamics simulation was further applied to explain the strong hygroscopicity of salts.