Investigation of heat treating conditions for silver-sheathed Y 1−xCa xBa 2Cu 4O 8 (x=0 and 0.1) superconductors

Abstract

The decomposition temperature of the Ca-doped Y124 materials in silver-sheathed wires rise from 775°C to 845°C with increasing oxygen partial pressure ( P O 2) from P O 2 =0.2 bar (in air) to P O 2 =1.0 bar (in pure oxygen). A critical transport current density ( J ct of 3.3 × 10 4 A/cm 2 is observed for silver sheathed Y(Ca) 124 wire at 4.2 K and 0 T by selecting the oxygen partial pressure and the annealing temperature. The grain boundary coupling is found to be insufficient by AC susceptibility measurements.