Two new transition metal nitrides, IrN2 and OsN2, were synthesized at high pressures and temperatures using laser-heated diamond-anvil cell techniques. Synchrotron x-ray diffraction was used to determine the structures of novel nitrides and the equations of states of both the parent metals as well as the newly synthesized materials. The compounds have bulk moduli comparable with those of the traditional superhard materials. For IrN2, the measured bulk modulus [K-0=428(12) GPa] is second only to that of diamond (K-0=440 GPa). Ab initio calculations indicate that both compounds have a metal:nitrogen stoichiometry of 12 and that nitrogen intercalates in the lattice of the parent metal in the form of single-bonded N-N units.
Phys. rev. lett. (Print)Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA; CNR, INFM, Democritos Natl Simulat Ctr, I-34014 Trieste, Italy; Univ Paris 06, Paris, France; Inst Phys Globe, Paris, France; Univ Edinburgh, Sch Phys, Edinburgh EH9 3JZ, Midlothian, Scotland; Univ Edinburgh, Ctr Sci Extreme Condit, Edinburgh EH9 3JZ, Midlothian, Scotland; Abdus Salam Int Ctr Theoret Phys, I-34014 Trieste, ItalyArticleEnglish