Effect of neutron irradiation on single-crystalV3Si: Neutron diffraction studies

Elastic and inelastic neutron-diffraction measurements have been made on a single crystal of ${\mathrm{V}}_3$Si as a function of fast-neutron irradiation. After irradiation to a fluence of 22.2×${10}^{18}$ n/${\mathrm{cm}}^2$ ($E>\mathrm{}1\mathrm{}$ MeV), refinement of the Bragg intensity data reveals a slight decrease in the long-range-order parameter to a value of about 0.9, and an increase in the average value of the mean-square displacement $〈u^2〉$ at low temperature of about 0.001 ${\mathrm{\AA }}^2$. Inelastic-scattering measurements show that the softening of the transverse-acoustical mode associated with the martensitic transition is absent in the irradiated crystal.