New group-14 element pernitrides synthesized at high pressure and temperature

Recent development in high pressure technique allows successful synthesizing novel materials as well as experimental exploring the deep inside of the earth and the condensed matter physics. We have been focusing on the nitrides and recently succeeded in the synthesis of the last remaining platinum group element pernitrides (RhN₂ and RuN₂) and 3d transition metal nitrides (NiAs-type FeN and CoN₂) under high pressure. Here, we would like to show new experimental results on the recent high-pressure synthesis of novel group-14 element pernitrides by using laser-heated diamond anvil cell and advanced characterization techniques of synchrotron radiation and Raman scattering etc. The direct nitridation of group-14 elements (Si, Ge and Sn) at 60 GPa resulted in the formation of pyrite-form of pernitrides, which is very interesting because the A₃N₄ (A=Si, Ge and Sn) have long time been known as the only nitrides of grou-14 elements so far. The synthesized pernitrides were quenched into ambient pressure and the quasi-single bonded nitrogen was evaluated based on the experimental data. We would like to discuss the details and crystal chemistry of group-14 element pernitrides.