Characteristics of Y1Ba2Cu3O7-x high-T c superconductor prepared by partial melting process

The superconducting Y₁Ba₂Cu₃O_7-x (123) and the Y₂Ba₁Cu₁O₅(211) powders in this study were prepared by pyrophoric synthesis method with Y₂O₃ (99.9 %), BaCO₃ (99.9 %), and CuO (99.9 %) powders. Samples of 123 and 211 pellets were first prepared and then piled to have a 123/211/123 arrangement before a partial melting process was applied for phase change of the center piece (211) to 123 phase through a peritectic reaction. The process parameters were a melting temperature of 1,040–1,070 °C and the mass of the 123 piece ranging from 0.4 to 1.2 g. The superconductivity, such as critical temperature (T_c), and mass susceptibility(χ) of bulk 123 and 211 samples were measured by AC four point probe method and AC susceptometer, respectively. The experimental results can be summarized as follows: the best preparation condition in the range examined was a melting temperature of 1,060 °C and mass ratio 123(A)/211(B)] of 2:1 with melting time of 30 minutes to yield the T_c of 88.5 K.