Formation of Anisotropic TI-1212, Tl-2212, Tl-1223 and Tl-2223 Particles using Aerosol Flow Reacted Powders

Highly anisotropic Particles of Tl-1212, Tl-2212, Tl-1223 and Tl-2223 superconductors were grown. The Tl-free precursor powders with the compositions Ba1Ca2Cu3Ag0.37O6 and Ba2Ca2Cu3Ag0.37O7were prepared using an aerosol flow reactor. These precursor powders were then post-annealed in 0.1 atm oxygen at 700 “C for 4h to reduce the carbon present and mixed with T12O3 (typical composition of TlX; x = 0.6-1.0). The Tl-containing powders were heated in sealed gold tubes between 650-890 °C for various times. X-ray diffraction showed that the TL-2212 and Tl-2223 phases were stable over a wide range of temperatures. Scanning electron microscopy showed evidence for the presence of high aspect-ratio particles. These highly anisotropic particles may of interest for the preparation of powder-in-tube and other powder deposited conductors, for current leads, and for grain alignment studies.