TlO charge reservoir changes on annealing Tl-1223 crystals
| Autor: | Eugene L. Venturini, David S. Ginley, Bruno Morosin |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
Superconductivity
Materials science Annealing (metallurgy) Analytical chemistry Energy Engineering and Power Technology chemistry.chemical_element Crystal structure Condensed Matter Physics Nitrogen Oxygen Electronic Optical and Magnetic Materials Crystal chemistry X-ray crystallography Electrical and Electronic Engineering Single crystal |
| Zdroj: | Physica C: Superconductivity. 183:90-98 |
| ISSN: | 0921-4534 |
| Popis: | Two TlCa 2 Ba 2 Cu 3 O 9−δ (Tl-1223) single crystals have been sequentially annealed in flowing oxygen or nitrogen and the complete crystal structure determined by leastsquares refinement of Mo Kα X-ray diffraction data. Small atomic displacements are consistent with a model in which small amounts of Tl 1+ present in the TlO layer are reversibly oxidized to Tl 3+ during mild oxygen anneals. Further, the disordered location of the Tl position off the four-fold, as determined by the usual least-squares refinement of X-ray data, appears to be related to the amount of oxygen present in the TlO layer in the particular crystal. Despite substantial changes in oxygen content in the TlO layers with annealing, Meissner data show very modest shifts in the superconducting transition temperature. T c 's are 117 K after extended oxygen anneals and 121 K for nitrogen anneals, suggesting little change in the carrier concentration in the CuO 2 planes. |
| Databáze: | OpenAIRE |
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