Aerosol flow reactor production of fine Y₁Ba₂Cu ₃O₇ powder: Fabrication of superconducting ceramics

Abstract

An aerosol flow reactor operating at 900-1000°C is used to prepare high-purity Y1Ba2Cu3O7 powders with a uniform chemical composition and a submicron to micron average particle size by thermally decomposing aerosol droplets of a solution consisting of the nitrate salts of Y, Ba, and Cu in a 1:2:3 ratio. The powders were at least 99% reacted based on thermogravimetric analysis, and the x-ray diffraction pattern is essentially that of Y1Ba2Cu3O7. Magnetic susceptibility measurements showed the powders to be superconducting with a transition at 90 K even for average reactor residence times as short as 20 s. Sintering cold-pressed pellets between 900 and 1000°C provides dense, fine grained (average size on the order of 1 μm) superconducting ceramics with sharp 90 K transitions. The grain size and shape of a final sintered part could be varied depending on powder production, processing, and sintering conditions.