Publication | Open Access
Effect of Fluorine Doping on the Synthesis of High-<i>T</i><sub>c</sub> Bi-Based Superconductors
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1989
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Superconducting MaterialFluorine DopingEngineeringBismuth-based SuperconductorsCrystal Growth TechnologySolid-state ChemistryChemistryBi-based SuperconductorsNovel SuperconductorsSuperconductivityQuantum MaterialsHigh Tc SuperconductorsClosed Reaction SystemLocal DeformationLow-temperature SuperconductivityMaterials ScienceHigh-tc SuperconductivityFluoride PowdersCrystallographyHigh-temperature SuperconductivityCondensed Matter PhysicsApplied Physics
High-Tc Bi-based superconductive oxides are prepared by doping a small amount of fluorine. Starting materials including fluoride powders are heated in air. Under the optimum synthesis condition a superconductor with Tc=113K and Tcend=106K is obtained; the firing temperature is 860°C, which is lower by about 20°C as compared to the case without doping fluorines. During the heating process most fluorines are released from the crystal, while the grains with the (243) phase grow very large at the expense of the (232) grains. High-resolution transmission electron microscopy (HRTEM) reveals a frequent intergrowth of layers as well as a local deformation of the supercell from the orthorhombic to monoclinic system. Another series of synthsis in a closed reaction system resulted in a less favorable result.