MELT-TEXTURED BI1.6PB0.4SR2CA2CU3O11 BULK SUPERCONDUCTORS FABRICATED IN A SIMPLE TUBE FURNACE

Using the simplified version of the melt-textured growth (MTG) technol ogy with a simple tube furnace, we have fabricated superconductors sat isfying the nominal composition Bi1.6Pb0.4Sr2Ca2Cu3O11. We would note that the material used in the fabrication was prepared by mixing a pre cursor Bi1.6Pb0.4Sr2Cu3Ox and CaO powder. This two step technique was found to be superior to the single step solid state reaction method af ter many trials. Scanning electron microscopy (SEM) and transmission e lectron microscopy (TEM) morphologies show that the melt-textured bulk samples are made up of stacks of highly textured single crystal-like layers. X-ray analysis as well as d.c. magnetization measurements were carried out and the J(c) value was found to be 1.3 x 10(3) A cm-(2) a t 77 K using the Bean model. At this stage, though J(c) is not so high as that of the best samples obtained from other complicated methods i nvolving special (hot) pressing and sintering techniques, we do not ne ed to apply any mechanical treatment at or after the heating procedure .