Synthesis of small particle size YBa2Cu3O7−xby a vapor phase process

A continuous process for synthesizing superconducting oxides in the form of submicron size particles is described. The materials are prepared from weakly acidic nitrate solutions containing the metals in the required proportions to form the 1–2–3 compound. The solutions are ultrasonically dispersed in an air or oxygen carrier stream as a very fine mist. The solution aerosol is passed through a tubular furnace at space velocities of approximately 1.0 s−1above 900°C and converted into oxide particles. The oxide particles are collected downstream either on 0.5 μm MILLIPORE(R)filters or are separated by electrostatic precipitation. The as-processed powder has the tetragonal structure of YBa2Cu3O7−x. The material can be converted into the superconducting orthorhombic 1–2–3 oxide by sequentially sintering at 900, 700, and 500°C in oxygen. The process can be readily scaled up for continuous production of oxide powder.