Hard x-ray radiation induced dissociation of N-2 and O-2 molecules and the formation of ionic nitrogen oxide phases under pressure

Applying hard x-ray photon radiation to a mixture of liquid N-2 and O-2 contained under pressure in a diamond-anvil cell, we break the strong covalent bonding of the molecules and form ionic compounds of complex nitrogen oxide ions at a pressure as low as 0.5 GPa previously expected for molecular phases. A new ionic NO(+)NO3(-) phase has been discovered at around 2 GPa. Structural characterization of the high-pressure ionic NO(+)NO3(-) phase with Rietveld refinement reveals an interesting layered monoclinic P2(1)/m structure with large elastic anisotropy, offering promises for generating materials with interesting properties and providing the basis for future theoretical studies.