We have developed a new method, which we term the 'powder melting process' (PMP) for the preparation of high J, YBCO superconductors. The YBCO conductors have been fabricated via a continuous melting and unidirectional solidification process using precursor powders of Y'BaCuO, ((211) phase) and BaCuO as starting materials. The transportJ, values of the samples, measured by a standard continuous ocfour-probe method, exceed 10800 A cm-' at 77 K and 1 T.A microstructural investigation indicated that the 123 grains are well oriented, and fine and dispersed 211 particles remained in the samples. YBCO conductors with various dimensions and shapes can be fabricated by the PMP method. This new approach has potential for the fabrication of oxide conductors with metal substrates, since its melting temperature is lower than that of other melting processes by about 100 "C.

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Bi2223 multifilamentary tapes with enhanced transverse resistivity by introducing Ca2CuO3 and SrZrO3 as interfilamentary barriers were prepared and their AC loss properties were examined under AC external magnetic field. To improve the deformation properties of these oxide powders, 20-30wt% Bi2212 powders were mixed with them. The mixed oxide powders were introduced among the twisted Bi2223 filaments by using dip-coating method. AC loss properties under AC parallel or perpendicular field were measured and compared with the results for the tape without barriers. The loss measurements were carried out by changing both the amplitude and the frequency of external field. Based on the experimental results, the effect of barrier introduction on the loss reductions was discussed.

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We illustrated that the elongated and shortened Cu–O bonds are responsible for the distinctly improved Jc of the YBCO film under both self-field and applied magnetic fields.

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