INTERNAL OXIDATION OF AG-Y1BA2CU3, AG-BI2 SR2CA1CU2 AND AG-BI1.8PB0.3SR2CA2CU3 ALLOYS, AND THEIR RESULTING SUPERCONDUCTING PROPERTIES

Three kinds of silver based alloys containing a component of Y1Ba2Cu3, Bi2Sr2Ca1Cu2 or Bi1.8Pb0.3Sr2Ca2Cu3 were internally oxidized and then heat treated. The oxide phase of Y1Ba2Cu3Ox, Bi2Sr2Ca1Cu2Oy or Bi2Sr2 Ca2Cu3Oz was precipitated in the silver matrix. For the Ag-Y1Ba2Cu3 th e critical temperatures, T, (onset) is 94 K and T(c) (offset) 88 K. Fo r the Ag-Bi2Sr2Ca1Cu2 T(c) (onset) is 96 K and T(c) (offset) 74 K, and the overall J(c) at 4.2 K is approximately 10(3) A. For the Ag-Bi1.8P b0.3Sr2Ca2Cu3 T(c) (onset) is 112 K, T(c) (middle) 83 K and T, (offset ) 70 K. The composition and distribution of the precipitated oxides an alysed by means of the X-ray image of EPMA are shown in cross-sectiona l maps.