YBa₂Cu₃O_7-x Superconductor powder synthesis by spray pyrolysis of organic acid solutions

A process based on the spray pyrolysis of an organic acid solution has been developed for the synthesis of spherical YBa₂Cu₃O_7-x superconducting powders. Depending on the solution viscosity, which is controlled by the degree of precursor polymerization, 'solid' organic YBC precursor particles are formed by spray pyrolysis. During the decomposition stage of spray pyrolysis these organic YBC precursor particles are converted to microporous particles comprised of inorganic nanocrystallites. The desired orthorhombic, superconducting phase is obtained by subsequent calcination at 850°C for 2 h in 10^-2 atm O₂, followed by annealing at 500°C for 4 h in flowing O₂. A.C. magnetic susceptibility results on powders and four-point resistance results on sintered pellets clearly show the transition to the superconducting state, confirming the developed process yields powders suitable for the synthesis of superconducting materials and monoliths.