MgO doping effects on flux pinning properties in Bi1.7Pb0.4Sr1.9Ca1Cu2O8+xcrystals

Flux pinning properties for Bi1.7Pb0.4Sr1.9Ca1CU2O8+x crystals with and wit hout MgO powder were studied. MgO particles having 100 nm average diameter coarsened to an average diameter of 1 mum in the Bi1.7Pb0.4Sr1.9Ca1Cu2O8+x crystals. Critical current densities for the MgO doped crystals increased i n temperature region from 20 to 77 K. MgO 5 wt.% crystals have higher J(c) than that of MgO 1 wt.% crystals in temperature range from 20 to 70 K. Scal ing behaviors for the MgO 5 wt.% crystals suggest that the MgO particles ar e the dominant pinning centers for the crystal in temperature range from 40 to 77 K. Irreversibility field for the MgO 5 wt.% crystals increases to al most the same value of the crystals with the Ag ion irradiated crystal. (C) 2001 Elsevier Science B.V. All rights reserved.