Volume and electrical resistivity change in niobium after neutron irradiation at 4.6 K

Pure niobium single crystals and wires were irradiated at 4.6 K by fast neutrons. Lattice parameter change Δa/a and resistivity change Δϱ were determined simultaneously at 4.2 and 9.2 K, respectively, and recovery was studied by an isochronal annealing program. The defect-specific ratio of both property changes was found to be (Δa/a)/Δϱ = (0.25 ± 0.015)× 103 (Ωem)−1. Using this result the volume change and resistivity change due to a Frenkel defect are discussed. For the recovery behaviour a model in analogy to that known for f.c.c. metals is given. The small differences in the recovery of lattice parameter and resistivity can be essentially interpreted by different impurity contents of the samples.