Ultra-High-Pressure Synthesis of Transition Metal – Nitrogen Binary Compounds

Abstract

The recent development of high-pressure experimental techniques combined with advanced characterization and analytical methods allows us to reveal the crystal chemistry of the transition metal-nitrogen binary compounds up to the megabar pressure regime. Novel early transition metal-nitrogen compounds, VN₂, Nb₂N₃, and MoC-type WN_0.6, have been synthesized by using a laser-heated diamond-anvil cell or DIA-type high-pressure apparatus. In addition to conventional high-pressure in-situ X-ray diffraction measurements, the low-temperature thermal expansion behavior and the valance state of transition metal ions of these newly synthesized compounds were revealed. In this article, the details of our experiments, and recent progress in high-pressure synthesis and crystal chemistry of transition metal nitrogen binary compounds are reviewed.