Improvement of J_c of Ag-Sheathed Bi-2212 Tapes Using Melt-Growth Technique under Reduced Oxygen Partial Pressure

概要

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The growth behavior of Bi-2212 under the oxygen partial pressure of 0.01 atm has been investigated using Ag-sheathed tapes. In the partial melt state, a Cu-free phase and (Sr, Ca)CuO_2 have been observed as solid phases. The Cu-free phase has been assigned, tentatively, as Bi_2Sr_2CaO_6. The grain size of the Cu-free phase has been found to depend critically on the starting composition. It decreases as the Sr content increases and the Ca content decreases, and accordingly, J_c of the melt-processed tapes increases. the optimum composition is Bi_2Sr_<2.3>Ca_<0.85>Cu_2O_z, and the maximum J_c is 1.5×10^5 A/cm^2 at 4 K.
社団法人応用物理学会の論文
1993-10-15