Effect of electron irradiation on the structure and properties of the MgB2 superconductor

This paper reports on the results of an investigation into the effect of irradiation of the Bardeen-Cooper-Schriefer superconductor MgB2 by electrons with a mean energy Ē ∼ 10 MeV at low doses (0 ≤ Φt ≤ ∼5 × 1016 cm−2) on the lattice parameters, the intensity and width of diffraction lines, the superconducting transition temperature T c , and the temperature dependence of the resistivity ρ(T) in the normal state. The results of structural investigations have revealed regularities in the defect formation in the magnesium and boron sublattices of the MgB2 compound as a function of the electron fluence. At the initial stage, irradiation leads to the formation of vacancies, originally in the magnesium sublattice and then in the boron sublattice. For fluences Φt ≥ ∼1 × 1016 cm−2, vacancies are formed in both sublattices. The evolution of the electrical and physical properties [T c , ρ273 K, residual resistivity ratio RRR = ρ273 K/ρ50 K, parameters of the dependence ρ(T)] under electron irradiation is in agreement with the regularities revealed in the formation of radiation-induced defects in the crystal lattice of the MgB2 compound.