Formation mechanism of insensitive tellurium hexanitride with armchair-like cyclo-N 6 anions.

The lower decomposition barriers of cyclo-N 6 anions hinder their application as high-energy-density materials. Here, first-principles calculations and molecular dynamics simulations reveal that enhancing the covalent component of the interaction between cyclo-N 6 anions and cations can effectively improve the stability of cyclo-N 6 anions. Taking tellurium hexanitride as a representative, the exotic armchair-like N 6 anions of tellurium hexanitride exhibit resistance towards electronic attack and gain extra stability through the formation of covalent bonds with the surrounding elemental tellurium under high pressures. These covalent bonds effectively improve the chemical barrier and insensitivity of tellurium hexanitride during blasting, which prevents the decomposition of solid cyclo-N 6 salts into molecular nitrogen. Furthermore, the high-pressure induced covalent bonds between cyclo-N 6 anions and tellurium enable the high bulk modulus, remarkable detonation performance, and high-temperature thermodynamic stability of tellurium hexanitride.