The effect of the neutron irradiation on the critical current and the microstructure of the melt-textured growth YBa2Cu3Oy

This paper reports on the effect of the fast neutron irradiation on the critical current properties and the microstructure of Melt-Textured Growth (MTG) YBa2Cu3O7-8 with fluences of 2.3 x 1016 n/cm2, 1.16 x 1017 n/cm2, and 5.8 x 1017 n/cm2 respectively. The hysteresis loops have been measured at 77 K and 1.5 K in the applied magnetic fields between -6 T and 6 T. The irreversibility lines H(T*) were also demonstrated. The critical magnetization current density Jc is up to 4.7 x 105 A/cm2 at 77 K in the field of 0.1 T for the irradiated sample with the fluence of 1.16 x 1017 n/cm2. It is tenfold higher than that of the unirradiated sample. This increase of Jc is due to the pinning at irradiation-induced pinning centers. Much higher neutron irradiation with fluence of 5.8 x 1017 n/cm2 is harmful to the increase of Jc value because the orthorhombic structure has been transformed into the tetragonal one. The amorphous state and the cellular structures are also observed in the irradiated MTG sample