Calcination and solid state reaction of ceramic-forming components to provide single-phase superconducting materials having fine particle sizesize

Patent · Mon Feb 03 23:00:00 EST 1992

OSTI ID:6901811

Balachandran, U; Poeppel, R B; Emerson, J E; Johnson, S A

This patent describes an improved method of preparing copper oxide superconducting materials having one of the following formulas, YBa[sub 2]CU[sub 3]O[sub x], YBa[sub 2]Cu[sub 4]O[sub 8], Bi[sub 2]Sr[sub 2]CaCu[sub 3]O[sub x] and Bi[sub 1.6]Pb[sub 0.4]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub x], wherein the material is prepared by the calcination and reaction of a precursor powder mixture containing at least one alkali earth carbonate. It comprises: preparing a stoichiometric precursor mixture containing at least one alkali earth carbonate, calcining and reacting the mixture by the following steps: heating the mixture in a furnace to a first temperature, simultaneously establishing a partial vacuum in the furnace of from about 213 to 2 [times] 10[sup 4] Pa, simultaneously providing flowing oxygen at a pressure from about 266 to 1300 Pa to the furnace, heating the mixture to at least 750[degrees]C, simultaneously controlling the rate of evolution of CO[sub 2] from the mixture as the mixture is heated, maintaining the mixture at 750[degrees]C for a period of time sufficient for CO[sub 2] evolution to cease and for the reaction of the mixture to go to completion forming a ceramic material, cooling the ceramic material to a third temperature, and increasing the pressure of the oxygen in the furnace to about ambient and soaking the ceramic in the oxygen for a period of time sufficient for the superconducting material to form.

• Assignee: Dept. of Energy, Washington, DC (United States)
• Patent Number(s): US 5086034; A
• Application Number: PPN: US 7-589562
• OSTI ID: 6901811
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
BISMUTH COMPOUNDS
CALCINATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COPPER COMPOUNDS
CUPRATES
DECOMPOSITION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FABRICATION
KINETICS
MATERIALS TESTING
OXYGEN COMPOUNDS
PARTICLE SIZE
PHYSICAL PROPERTIES
PLASMA
PRECURSOR
PYROLYSIS
REACTION KINETICS
SIZE
SOLID-STATE PLASMA
SUPERCONDUCTING DEVICES
SUPERCONDUCTIVITY
TESTING
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS