Japanese Journal of Applied Physics · 1995 · 17 citations · 10 references
Natural SciencesMaterials SciencePhysicsCondensed Matter PhysicsPhase TransformationsSolid State PhysicsElectrical ConductivityMagnetism In SolidsNanocompositesPhase TransitionsSuperconducting MaterialsSuperconducting Thin FilmsCritical Current DensityCritical Current PerformanceCuprate SuperconductorsCurrent DensitySuperconducting CeramicsSuperconducting CompositesSuperconducting PropertiesX-ray Diffraction Analysis
In the Tl-Ba-Ca-Cu-O (TBCCO) diffusion composites, critical current ( I c ) at 77 K is significantly improved by fluorine (F) addition to the coating layer. The F addition decreases the degradation of I c under magnetic field at 77 K, and shifts the irreversibility lines to higher temperatures. The X-ray diffraction study reveals that F addition promotes the phase transformation from 2223 to 1223. Meanwhile, annealing in flowing O 2 at 550° C-600° C also increases I c at 77 K. O 2 annealing seems to improve the weak links between superconducting grains. The largest transport critical current density ( J c ) of the specimen with F addition and O 2 annealing exceeds 10000 A/cm 2 at 77 K. In the present TBCCO diffusion composites with F addition, the effect of phase transformation on I c performance has been clearly observed.
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