93Nb NMR study of an ordered and a disordered non-stoichiometric niobium carbide

Using pulse-modulated NMR spectroscopy of 93 Nb, a non-stoichiometric niobium carbide, NbC y has been investigated. NMR spectra have been obtained for NbC y samples with different vacancy concentrations in the carbon sublattice. The NMR spectra of an ordered niobium carbide, NbC 0.83 , have been found to differ appreciably from those of a disordered one. The parameters of the quadrupole interactions have been calculated. The NMR spectral lines reflect the various types of environment of the niobium atoms. Short-range order in an ordered and a disordered niobium carbide has been identified. The presence of an ordered Nb 6 C 5 phase has been confirmed.