Correlation between structural relaxation enthalpy and superconducting properties of amorphous Zr70Cu30 and Zr70Ni30 alloys

A. Inoue, K. Matsuzaki, N. Toyota, H. S. Chen, T. Masumoto, T. Fukase

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9 Citations (Scopus)

Abstract

The anneal-induced change in the superconducting properties together with the irrecoverable relaxation enthalpy (ΔHi,exo) and recoverable relaxation enthalpy (ΔHr,endo) of amorphous Zr70Cu30 and Zr70Ni30 alloys was examined. The increase in Δi,exo and the degradation of Tc progress logarithmically with annealing time ta in a temperature range of 373 to 523 K. The activation energy and the attempted frequency were respectively estimated to be 1.5eV and 6.6 × 1013 sec-1 for the increase in ΔHi,exo and 1.5eV and 1.9×1014 sec-1 for the degradation of Tc. The recoverable structure relaxation exerts little effect on Tc. Based on the agreement between the kinetic parameters for the changes of ΔHi,exo and Tc, it appears that the degradation of Tc on annealing is associated with the irrecoverable structural relaxation as a result of the annihilation of frozen-in defects and the topological and compositional atomic rearrangement. The values of the attempted frequency being of the order of Debye frequency suggest that the irrecoverable structural relaxation processes occur more or less independently from each other. The dressed density of electronic states at the Fermi level, N(Ef)(1+λ), determined from the measured values of ρn and -(d Hc2/d T)Tc using GLAG (theory), was found to have a similar annealing dependence to that of Tc. The degradation of Tc by the irrecoverable relaxation was thus inferred as resulting from the decrease in λ due to the decrease in N(Ef) and the increases in M and ω. Furthermore, the irrecoverable structural relaxation resulted in a significant depression of fluxoid pinning force and was interpreted as due to an enhanced structural homogeneity on the scale of coherence length.

Original languageEnglish
Pages (from-to)2323-2334
Number of pages12
JournalJournal of Materials Science
Volume20
Issue number7
DOIs
Publication statusPublished - 1985 Jul 1

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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