Spray-pyrolysis process of preparing superconductor precursors

A spray-pyrolytic process for the preparation of multi-element metal oxide powders useful as precursors of high-temperature superconductor ceramics, which comprises burning aerosols of aqueous solutions containing metal nitrate salts admixed in the required stoichiometric proportion in a hydrogen/oxygen flame, wherein the aerosol is sprayed through an independently operated hydrogen/oxygen flame, in such a way that a flame temperature of 800.degree. to 1100.degree. C. is maintained, and contact of the aerosols and the powders generated during the process with carbon or carbon-containing compounds or materials is avoided and wherein the metal nitrate salts contain oxygen and the oxygen feed to the hydrogen/oxygen flame is reduced after starting the process in such a manner that a substantially self-sustaining combustion takes place between the hydrogen and oxygen within the metal nitrate salt,

• and wherein nitrogen-based reducing agents and/or nitrogen-based oxidizing agents are introduced into the metal salt solution or independently sprayed into the reactor as an aqueous solution so as to control the overall reduction/oxidation quotient of the system.