Short-range-order determination in quenched NbC_0.73 by elastic diffuse neutron scattering

The elastic diffuse neutron scattering of an NbC_0.73 single-crystal has been measured at room temperature on two different spectrometers, the four-circle D10 at the HFR-ILL (Grenoble), and the two-axis G44 with time-of-flight analysis at the Laboratoire Léon Brillouin (Saclay). The data were treated either by Fourier transformations or by least-squares fit. The short-range-order parameters and the interatomic static displacements obtained by the various experiments and/or data treatment are in good agreement: carbon vacancies tend to be third neighbours in the f.c.c. metalloid sublattice and metal atoms relax away from the vacancy first neighbours by ~0.05 Å. It is shown that the treatment of diffuse scattering data limited to two reciprocal planes [(001) and (10)] gives satisfactory results.