Influence of growth parameters on the microstructure of directionally solidified Bi sub 2 Sr sub 2 CaCu sub 2 O sub y

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1990.1834· OSTI ID:6339768

Cima, M J; Jiang, X P; Chow, H M; Haggerty, J S; Flemings, M C ^[1]; Brody, H D ^[2]; Laudise, R A; Johnson, D W ^[3]

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1. Massachusetts Institute of Technology, Cambridge, MA (USA)
2. University of Pittsburgh, Pittsburgh, PA (USA)
3. AT T Bell Laboratories, Murray Hill, NJ (USA)

Laser-heated float zone growth was used to study the directional solidification behavior of Bi-Sr-Ca-Cu-O superconductors. The phases that solidify from the melt, their morphology, and their composition are altered by growth rate. Highly textured microstructures are achieved by directional solidification at all growth rates. The superconducting phase is found always to have the composition Bi{sub 2.5}Sr{sub 2}CaCu{sub 2.2}O{sub {ital y}} when grown from boules with composition 2:2:1:2 (BiO{sub 1.5}:SrO:CaO:CuO). Planar growth fronts of Bi{sub 2.5}Sr{sub 2}CaCu{sub 2.2}O{sub {ital y}} are observed when the temperature gradient divided by the growth rate ({ital G}/{ital R}) is larger than 3{times}10{sup 11} K-sec/m{sup 2} in 2.75 atm oxygen. Thus, the 2212 compound was observed to solidify directly from the melt at the slowest growth rates used in this study. Measurement of the steady-state liquid zone composition indicates that it becomes bismuth-rich as the growth rate decreases. Dendrites of the primary solidification phase, (Sr{sub 1{minus}{ital x}}Ca{sub {ital x}}){sub 14}Cu{sub 24}O{sub {ital y}}, form in a matrix of Bi{sub 2.5}Sr{sub 2}CaCu{sub 2.2}O{sub {ital y}} when {ital G}/{ital R} is somewhat less than 3{times}10{sup 11} K-sec/m{sup 2}. Observed microstructures are consistent with a peritectic relationship between Bi{sub 2.5}Sr{sub 2}CaCu{sub 2.2}O{sub {ital y}}, (Sr{sub 1{minus}{ital x}}Ca{sub {ital x}}){sub 14}Cu{sub 24}O{sub {ital y}}({ital x}=0.4), and a liquid rich in bismuth at elevated oxygen pressure. At lower values of {ital G}/{ital R}, Sr{sub 3}Ca{sub 2}Cu{sub 5}O{sub {ital y}} is the primary solidification phase and negligible Bi{sub 2.5}Sr{sub 2}CaCu{sub 2.5}O{sub {ital y}} forms in the matrix.

• OSTI ID: 6339768
• Journal Information: Journal of Materials Research; (USA), Journal Name: Journal of Materials Research; (USA) Vol. 5:9; ISSN JMREE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
BISMUTH OXIDES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL GROWTH
CRYSTAL STRUCTURE
DATA
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
HIGH-TC SUPERCONDUCTORS
INFORMATION
MELTING
MICROSTRUCTURE
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SOLIDIFICATION
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEXTURE
TRANSITION ELEMENT COMPOUNDS
ZONE MELTING