Synthesis of platinum-group-metal dinitrides by direct nitridation under ultra-high pressures

Abstract

It was assumed that platinum-group-metals neither react with nitrogen nor form their nitrides at ambient pressure.However, ultra-high-pressure conditions of more than several dozen GPa have recently made it possible to synthesize their dinitrides by a direct nitridation. This short communication reports on new worldwide trends f of novel metal(M) nitride studies, such as MN₂, M₂N₃, M₃N₄, particularly platinum-group-metal dinitrides, which can be synthesized only under ultra-high-pressures. The first section deals with an ultra-high-pressure synthesis technique using a diamond anvil cell combined with an infra-red-laser heating system. The next section describes their synthesis, phase stability, crystal structure, and physical properties. Other novel transition-metal dinitrides are also introduced briefly, particularly focusing on the growth of CrN₂ single crystals, which exhibit the first and only success among novel metal dinitrides.