Chemical Potential of Nitrogen at High Pressure and High Temperature: Application to Nitrogen and Nitrogen-Rich Phase Diagram Calculations

The chemical potential change of nitrogen at high pressure/high temperature is a crucial ingredient for predicting the formation of nitrogen-rich compounds. Here, we provide intelligible data for the chemical potential change of molecular nitrogen at temperature and pressure conditions relevant for experiments in the diamond anvil cell. In combination with first-principles calculations, we derive pressure–temperature phase diagrams readily accessible to guide experimental efforts. We show the validity of our approach for three characteristic systems: pure nitrogen and nitrogen-rich Si–N and Ti–N phases appearing at high pressure/high temperature.