초록 ▼

The present invention pertains to a method of preparing particles of superconducting ceramic powders, which method comprises: (a) dissolving the soluble salts of the cations in aqueous medium; (b) obtaining a solution having pH of between about 4 and 7 by optionally treating the aqueous medium with

The present invention pertains to a method of preparing particles of superconducting ceramic powders, which method comprises: (a) dissolving the soluble salts of the cations in aqueous medium; (b) obtaining a solution having pH of between about 4 and 7 by optionally treating the aqueous medium with ammonia, or ammonium hydroxide; (c) atomizing the solution of step (b) onto liquid nitrogen at about -196°C.; (d) removing the liquid nitrogen by evaporation; (e) removing the water by sublimation at reduced pressure; (f) heating the solid residue of step (e) at 40-60°C. at reduced pressure; (g) calcining the solid residue in flowing oxygen or air at temperature of between about 200°to 895°C.; and (h) cooling the solid at a temperature of between about 900°C. and ambient temperature in sufficient air or oxygen and recovering the superconducting powder having an average diameter of between about 0.1 and 10 microns. Optionally, substep (h), additionally includes during cooling, the annealing of the particles in sufficient oxygen at between about 200°and 500°C. for between about 2 and 30 hrs. YBa2Cu3O7-d (where d is 0-1) is preferred superconducting powder.

대표청구항 ▼

An improved method of preparing fine particles of superconducting ceramic powders, which method comprises: (a) dissolving the soluble salts of cations in aqueous medium; (b) obtaining a substantially saturated solution of the salts and adjusting the pH to between about 4 and 7; (c) atomizing the sol

An improved method of preparing fine particles of superconducting ceramic powders, which method comprises: (a) dissolving the soluble salts of cations in aqueous medium; (b) obtaining a substantially saturated solution of the salts and adjusting the pH to between about 4 and 7; (c) atomizing the solution of step (b) onto liquid nitrogen at about -196°C.; (d) removing the liquid nitrogen by evaporation of the nitrogen under reaction conditions such that the ice-salt crystals do not coalesce into larger particles; (e) removing the ice by sublimation at reduced pressure under reaction conditions such that the ice-salt crystals do not melt; (f) heating the solid residue of step (e) at about 40°-60°C. at reduced pressure under the reaction conditions such that the residue does not melt; (g) calcining the solid residue in sufficient oxygen or air at temperature of between about 200°and 895°C.; and (h) cooling slowly the solid at a temperature of between about 900°C. and ambient temperature in sufficient air or oxygen concurrently annealing the particles in flowing oxygen or air at between about 200°and 500°C. for between about 2 and 30 hrs and recovering the superconducting solid powder having an average diameter of between about 0.1 and 10 microns.