Flux method for producing crystals of superconducting YBa sub 2 Cu sub 3 O sub 7

Patent · Tue Feb 26 04:00:00 EST 1991

OSTI ID:5663767

Wnag, Z Z; Ong, N P

This patent describes a method for producing single crystals of YBa{sub 2}Cu{sub 3}O{sub 7} which undergo a transition to the superconducting state above 90 K. It comprises: preparing a flux composition by mixing BaO{sub 2} and CuO powders in the molecular weight ratio of approximately 1:1, layering on top of the mixture powdered YBa{sub 2}Cu{sub 3}O{sub 7} in an amount up to approximately 20% of the total weight of the BaO{sub 2}-CuO mixture, firing the mixture in air at approximately 930{degrees} C--950{degrees} c for approximately 15 hours or longer to thereby form BaCuO{sub 2+{ital x}} where x = 0.10 to 0.20, and thereafter raising the temperature from 930{degrees} C--950{degrees} C. to 980{degrees} C--1040{degrees} C. within {1/2} hour to melt the BaCuO{sub 2+{ital x}} to form a flux; maintaining the temperature of the flux at 980{degrees} C--1040{degrees} C. for an amount of time sufficient to dissolve the YBa{sub 2}Cu{sub 3}O{sub 7} into the molten BaCuO{sub 2+{ital x}}, cooling thereafter the flux to approximately 1020{degrees}C--980{degrees} C; providing an oxygen gas flow to the flux when the temperature is approximately 1020{degrees} C-980{degrees} C; maintaining the flux in an oxygen gas flow at approximately 980{degrees} C. for approximately at least 30 minutes; and cooling thereafter the flux slowly to room temperature in continuing oxygen gas flow.

• Assignee: Princeton Univ., Princeton, NJ (USA)
• Patent Number(s): A; US 4996186
• Application Number: PPN: US 7-228979
• OSTI ID: 5663767
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
LOW TEMPERATURE
OXIDES
OXYGEN COMPOUNDS
SUPERCONDUCTORS
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES