Tl₂Ca₁Ba₂Cu₂O_8+x high T_c superconductors processed by the sol‐gel technique Available to Purchase

Tl₂Ca₁Ba₂Cu₂O_8+x high T_c superconductors were developed using a new alkoxide sol‐gel system. Barium‐, calcium‐, thallium‐methoxyethoxide and Cu(II) ethoxide precursors were used for the formation of homogeneous sols. Solubility of the Cu(II) ethoxide was aided by using a 2‐methoxyethanol/methyl ethylketone/toluene solvent system. The sols were characterized by small‐angle x‐ray scattering and transmission electron microscopy. The average particle size was 50 nm and the fractal dimension of these particles was 1.8. Powders were produced by rotary evaporation followed by thermal treatment in a closed container with excess thallium at 900 °C for various calcination times. Powders were characterized by x‐ray diffraction, resistivity, and magnetic susceptibility measurements, and chemical analysis. Samples exhibited transition temperatures between 100 and 110 K depending upon the processing conditions.