Title :
Formation of anisotropic Tl-1212, Tl-2212, Tl-1223 and Tl-2223 particles using aerosol flow reacted powders
Author :
Paranthaman, M. ; Goyal, A. ; Heatherly, D.E. ; Kroeger, D.M.
Author_Institution :
Div. of Chem. & Anal. Sci., Oak Ridge Nat. Lab., TN, USA
fDate :
6/1/1995 12:00:00 AM
Abstract :
Highly anisotropic particles of Tl-1212, Tl-2212, Tl-1223 and T1-2223 superconductors were grown. The Tl-free precursor powders with the compositions Ba/sub 1/Ca/sub 2/Cu/sub 3/Ag/sub 0.37/O/sub 6/ and Ba/sub 2/Ca/sub 2/Cu/sub 3/Ag/sub 0.37/O/sub 7/ were prepared using an aerosol flow reactor. These precursor powders were then post-annealed in 0.1 atm oxygen at 700/spl deg/C for 4 h to reduce the carbon present and mixed with Tl/sub 2/O/sub 3/ (typical composition of Tl/sub x/; x=0.6-1.0). The Tl-containing powders were heated, in sealed gold tubes between 650-890/spl deg/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.<>
Keywords :
X-ray diffraction; annealing; barium compounds; calcium compounds; grain size; high-temperature superconductors; powders; scanning electron microscopy; sintering; thallium compounds; 4 h; 650 to 890 C; 700 C; Tl-1212; Tl-1223; Tl-2212; Tl-2223; Tl-free precursor powders; TlBaCaCuO; X-ray diffraction; aerosol flow reacted powders; grain alignment; high aspect-ratio particles; high temperature superconductor; post-annealed; powder deposited conductors; powder-in-tube; scanning electron microscopy; Aerosols; Anisotropic magnetoresistance; Conductors; Gold; Inductors; Powders; Scanning electron microscopy; Superconductivity; Temperature distribution; X-ray diffraction;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
