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 (E) over bar similar to 10 MeV at low doses (0 <=phi t <= similar to 5x10(16) 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 rho(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 phi t >=similar to 1x10(16) cm(-2) stop, vacancies are formed in both sublattices. The evolution of the electrical and physical properties [T-c , rho(273 K), residual resistivity ratio RRR=rho(273 K)/rho(50 K), parameters of the dependence rho(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.