Electrical resistivity of small dislocation loops in irradiated copper

Small loops and stacking fault tetrahedra of sizes 1 to 10 nm were created during irradiation of copper with 14 MeV neutrons at room temperature. The electrical resistivity of these defect clusters has been investigated using a combination of resistivity and electron microscopy techniques. The dislocation specific resistivity of the loops was determined to be ρsub(d) ≅ 1.4 X 10 25Ω m3 at a temperature of 4.2 K, in fair agreement with the literature value for straight dislocations in copper. The effective Frenkel pair resistivity of the point defects in the loops was constant over the fluence range 1 X 1020 to 2 X 1024 n m-?2, with a value of about 1.7 μΩm per unit concentration of Frenkel pairs. This is only slightly less than the specific resistivity of isolated Frenkel pairs in copper, and suggests that clustering of point defects does not necessarily lead to a large decrease in the Frenkel pair resistivity. The ratio of surviving to created point defects (η) decreased from 11 to 4.7% as the neutron fluence increased from 1 X 1020 to 3 X 1021 n m-2. (author)