Fabrication and process-related properties of superconducting oxide YBa sub 2 Cu sub 3 O sub 7 minus y

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5577824

Chu, Chungtse

The discovery of superconductivity above liquid nitrogen temperature (77 K) has made it feasible to utilize superconductors in various technological applications long considered to be impractical. Successful engineering of these new superconducting ceramics into useful forms, however, requires both a better understanding of the processing-microstructure-property relationships for these materials and the development of advanced processing techniques. In this dissertation research, the three basic steps in fabrication of ceramic articles, namely: powder preparation, forming, and sintering were studied for the superconducting oxide YBa{sub 2} Cu{sub 3} O{sub 7{minus}y}. Submicron powder of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} was synthesized using the amorphous citrate process. Nearly single-phase YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} powders with excellent sinterability were obtained by firing a citrate-nitrate precursor to 900C for 2 hr. A novel ceramic forming technique, electrophoretic deposition, was applied to produce YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} coatings on both metallic and nonmetallic substrate materials. Coatings in the range of 200 to 500 {mu}m thick were readily produced on a variety of shapes including wires, coils, and plates. Finally, the sintering behavior and grain growth of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} ceramics were studied at sintering temperatures of 925, 950, and 975C. The grain growth of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y} followed D{sup 5} kinetics when sintered at 925 and 950C. At 975C, the kinetics changed to cubic behavior, an effect which could be attributed to the formation of a liquid phase at the grain boundaries. For the most part, the different processing conditions and microstructures did not affect the superconducting properties of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y}. Only the critical current density (J{sub c}) exhibited much of an effect.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 5577824
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360207 -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRITICAL CURRENT
CRYSTAL STRUCTURE
CURRENT DENSITY
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
FABRICATION
GRAIN GROWTH
HIGH-TC SUPERCONDUCTORS
MATERIALS WORKING
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PENETRATION DEPTH
PHYSICAL PROPERTIES
SINTERING
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES