High-pressure chemistry of transition metal polynitrides*

The high-pressure chemistry of nitrogen and nitrogen-rich compounds have been in a focus of many studies in the recent years due to both fundamental and practical interest and due to the improvement of high-pressure synthetic and characterization techniques. Poly-nitrogen compounds are usually considered as potential high energy density materials (HEDM) due to the remarkable difference in the average bond energy between the single N–N bond, the double N=N bond , and the triple N≡N bond. Numerous polynitrogen compounds with various nitrogen polymeric networks were theoretically predicted, but there are only a very few experimental attempts to obtain such compounds.
In the present work we have systematically studied reactions between 5d transition metals and nitrogen at pressures up to 130 GPa in laser-heated diamond anvil cells. All 5d metals except Au react with nitrogen at these conditions resulting in the formation of polynitrides with various types of polynitrogen species. Here we will discuss current progress in high-pressure chemistry of nitrogen, methodhological challenges and novel approaches to the high-pressure synthesis.