THICK HIGHLY TEXTURED (BI,PB)-2223 CERAMICS

Dense (Bi, Pb)(2)Sr2Ca2Cu3O10+x ceramics textured by sinter-forging ex hibit superconducting properties among the best for polycrystalline bu lk 2223 materials. Investigations showed that the deformation during t he sinter-forging process is mainly responsible for the grain alignmen t of the ceramics. A sharp texture can only be obtained after a strong deformation from the starting cold-pressed powder to the final thin f orged disc. To obtain thick ceramics. several thin and highly identica lly textured discs were linked together by an additional short sinter- forging step. Microscopic observations showed that the interface betwe en the discs disappeared after the hot treatment. Transport critical c urrent measurements performed at 77 K through bars of different sizes confirm that, through an equal texture, the critical current density ( J(CT) = 10 000 A cm(-2)) is nearly constant with the shape of the bar section: thin or thick, narrow or wide. A ceramic composed of many sta cked and sinter-forged discs allowed resistivity and J(CT) to be measu red along the sinter-forging axis. Low anisotropic ratios confirmed th e strong link between the thin discs and a very homogeneous whole cera mic. This shape processing of bulk 2223 ceramics is thus attractive fo r the fabrication of current leads and limiters with high capabilities .