Electron irradiation effects in doped high temperature superconductors YBa2Cu3−x MxOy (M = Fe, Ni; x=0; x=0:01)

Abstract

AbstractThe influence of irradiation by electrons with an energy of 8 MeV, at dose intervals between 1013 and 2×1018el/cm2, on the properties of impurity doped, high-temperature superconductor YBa2Cu3−x MxOy (M = Fe, Ni; x=0; x=0:01) ceramics has been studied.It has been established that, as the irradiation dose is increased, the onset temperature of the transition to the superconducting state (T con), and the intergranular weak link coupling temperature between granules (T mJ), exhibit an oscillation around their initial values of approximately about 1–1.5 K. This oscillation indicates that the process of radiation defect formation in HTSC occurs in multiple stages. It was also found that the critical current (J c)decreases with an increase of the irradiation dose, and exhibits a local minimum at a dose of 8×1016el/cm2coinciding with minima for T con and T mJ at this dose. It was found that the introduction of Fe atoms to the ceramic decreases T mJ, while introducing Ni atoms decreases both T con and T mJ; it is suggested that this is a result of Ni substitution of Cu both in Cu2 plane sites and Cu1 chain sites. The introduction of Ni causes a large change in the intergranular critical current density, J c. A critical irradiation dose is obtained (2×1018)after which all HTSC parameters strongly decrease, i. e. the superconductivity of HTSC is destroyed.