Calcium-substituted Y-Ba-Cu-O superconductors with enhanced T sub c synthesized at elevated oxygen pressures

Journal Article · Thu Mar 01 04:00:00 EST 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.41.4118· OSTI ID:6977307

Morris, D E; Narwankar, P; Sinha, A P.B.; Takano, K; Fayn, B; Shum, V T ^[1]

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1. 2-300 Lawrence Berkeley Laboratory, Berkeley, California 94720 (USA)

Calcium substitution in the Y-Ba-Cu-O system at elevated {ital P}(O{sub 2}) results in superconducting compounds with novel and enhanced properties: tetragonal Ca{sub {ital x}}Y{sub (1{minus}{ital x})}Ba{sub 2}Cu{sub 3}O{sub {ital y}} with {ital T}{sub {ital c}}=86 K for {ital x}=0.2 prepared at {ital P}(O{sub 2})=16 bars, and Ca{sub {ital x}}Y{sub (1{minus}{ital x})}Ba{sub 2}Cu{sub 4}O{sub {ital y}} (1:2:4) with {ital T}{sub {ital c}}=89 K for {ital x}=0.1 prepared at 50--200 bars. Calcium substitution shifts the phase-stability boundary between 1:2:3, 2:4:7, and 1:2:4 phases to higher {ital P}(O{sub 2}), and stabilizes a tetragonal 1:2:3 structure at moderately elevated {ital P}(O{sub 2}) {ital without} substantial decrease in {ital T}{sub {ital c}}. The {ital T}{sub {ital c}} of 1:2:4 increases with Ca substitution up to {ital x}=0.1, and then decreases gradually for larger {ital x}, possibly because of excessive hole concentration.

• OSTI ID: 6977307
• Journal Information: Physical Review, B: Condensed Matter; (USA), Journal Name: Physical Review, B: Condensed Matter; (USA) Vol. 41:7; ISSN 0163-1829; ISSN PRBMD
• 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
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
AUGMENTATION
BARIUM COMPOUNDS
BARIUM OXIDES
CALCIUM ADDITIONS
CALCIUM ALLOYS
CHALCOGENIDES
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
HOLES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STOICHIOMETRY
SUPERCONDUCTORS
TETRAGONAL LATTICES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES