Variations in cohesive energy and formation energy in the presence of cation vacancies (MB2 → M0.75B2), as well as in the formation energy of cation-site vacancies, were analyzed for s-, p- and d-metal diborides by using the FLMTO-GGA full-potential approach. It was found that cationic non-stoichiometry of MB2 phases was achievable only when they were prepared under non-equilibrium conditions.

Effect of Metal Vacancies on the Energy Parameters of s-, p-, and d-Metal Diborides. I.R.Shein, A.L.Ivanovskii: Russian Journal of Inorganic Chemistry, 2007, 52[2], 238-41