Separation of the intrinsic pressure effect on Tc of YBa2Cu3O6.7 from a Tc enhancement caused by pressure-induced oxygen ordering
| Autor: | J. Metzger, Th. Wolf, H. Wühl, H.A. Ludwig, Kai Grube, T. Weber, Walter H. Fietz |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
chemistry.chemical_classification
Materials science High-temperature superconductivity Condensed matter physics Relaxation (NMR) Hydrostatic pressure Time constant Energy Engineering and Power Technology Thermodynamics chemistry.chemical_element Condensed Matter Physics Oxygen Electronic Optical and Magnetic Materials law.invention Degree (temperature) chemistry law Crystallite Electrical and Electronic Engineering Inorganic compound |
| Zdroj: | Physica C: Superconductivity. 214:371-376 |
| ISSN: | 0921-4534 |
| DOI: | 10.1016/0921-4534(93)90840-m |
| Popis: | The superconducting transition temperature Tc of polycrystalline YBa2Cu3O6.7 has been investigated under purely hydrostatic He-gas pressure. In a series of experiments, it has been shown that the degree of oxygen ordering depends on the applied pressure and the storage temperature TS of the sample. At temperatures below ≈240 K, there is no indication for oxygen ordering. When pressure is applied at such low temperatures, the Tc values show no relaxation effects, and (dTc/dp)i=7.4 K/GPa is observed which we believe is intrinsic. At temperatures above 240 K, the oxygen sublattice reacts reversibly to the applied temperature and pressure. Changes of the storage temperature or pressure cause Tc relaxations with time constants that are temperature dependent. When the relaxations were completed the effects of pressure and storage temperature on Tc are independently determined to be: (1) a pressure-independent effect of the storage temperature Tc with dTc/dTS=−0.02, (2) a temperature-independent effect of pressure-induced oxygen ordering with (dTc/dp)o=4.1 K/GPa. For temperatures above 240 K, the intrinsic and the oxygen ordering effect add to dTc/dp=11.5 K/GPa. |
| Databáze: | OpenAIRE |
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