The critical current of the Chevrel phase superconductor lead-molybdenum-sulphur with gadolinium
| Autor: | M.J. Goringe, S. Ali, H.A. Hamid, Damian P. Hampshire, C.J. Eastell, D.N. Zheng |
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| Předmět: |
Superconductivity
Materials science Condensed matter physics Gadolinium Analytical chemistry Energy Engineering and Power Technology chemistry.chemical_element Atmospheric temperature range Condensed Matter Physics Heat capacity Electronic Optical and Magnetic Materials chemistry Electrical resistivity and conductivity Grain boundary Electrical and Electronic Engineering Pinning force Critical field |
| Zdroj: | Scopus-Elsevier |
| Popis: | The critical current density J c has been measured in a series of Chevrel phase Pb 1− x Gd x Mo 6 S 8 ( x = 0, 0.1, 0.2 and 0.3) bulk samples made using a hot isostatic pressing process. Adding Gd markedly increases the critical temperature, and the upper critical field found using resistivity, susceptibility and heat capacity measurements. The grain boundaries are found to be clean when observed using TEM. However, increasing the level of Gd, causes J c and the irreversibility field B irr to decrease dramatically. In particular, J c becomes more field dependent as more Gd is added. The pinning force density for all samples can be described either by a Kramer relation F p = J c × B ∝ b 1 2 (1 − b) 2 or by an exponential relation J c = α ( T )exp[− B / β ( T )], over a wide field and temperature range. This indicates that one mechanism controls J c in all the samples. This study shows that adding Gadolinium improves the intrinsic properties ( T c , B c2 ( T )) and yet simultaneously degrades the extrinsic properties ( J c , B irr ). It is suggested that the Gadolinium acts as an oxygen getter which improves the intrinsic properties of the grains but causes local compositional variations at the grain boundaries which reduces J c . |
| Databáze: | OpenAIRE |
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