Heat of mixing in HfCsub(x)Nsub(1-x) compounds from XPS core level binding energy shifts

The XPS core level binding energies for the Hf4fsub(7/2), Cls and Nls level in several nearly stoichiometric HfCsub(x)Nsub(1-x) compounds are reported. Using the thermochemical model to calculate core level binding energy shifts in metals the heat of mixing as function of the HfC/HfN ratio is calculated from the position of the Cls binding energies. In addition it is shown that the Hf4fsub(7/2) and Nls binding energies can be used to obtain further thermochemical data for these compounds. (author)