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Dedicated to Prof. Dr. Dr. h.c. P. GORLICH, on the occasion of his 65th birthday Basing on the general conceptions of the band structure of stoichiometric IVa subgroup transition metal monocarbides and assuming two types of atomic interactions a conduction band model for nonstoichiometric carbides has been elaborated which takes into account the vacancies in the carbon sublattice. It is assumed that the formation of vacancies is accompanied by the appearance of local electronic levels in the vicinity of the Fermi level of stoichiometric carbide which, in the case of high concentrations of C-vacancies, form a subband of unscreened Me-Me bonds. This results in a filling of the Me-C band, a shift of the Fermi level into the Me-Me band, followed by an increase of the electron density of states and an increase of the Ferrni level. The increasing density of states leads to an increase in the magnetic susceptibility

The magnetic susceptibility of zirconium monocarbide has been studied as a function of temperature and concentration in the homogeneity region 0.58 5 x 5 1.0 and a t temperatures from 20 t o 1300 OK. It is shown that the temperature dependence x(T) of all the samples may be described by the equations const at 'r < 290 " K , ' = { ; ( , + a T a t T > 2 9 0°K .The obtained results are discussed in terms of concepts available on the electronic structure of the cubic carbides of the group IVa and Va transition metals. A "flat" minimum was found in the curve N ( E ) lying near stoichiometric composition of the monocarbides.

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