On the the crystal growth and chemistry of the new electron-type superconducting oxides

J. M. Tarascon, E. Wang, L. H. Greene, R. Ramesh, B. G. Bagley, G. W. Hull, P. F. Miceli, Z. Z. Wang, D. Brawner, N. P. Ong

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

The effect on transport and superconducting properties produced by changes in x and y in the Nd2-xCexCuOy compound were studied in both polycrystalline ceramics and single crystals. Thermogravimetric analysis shows that the total oxygen content y for the as-prepared samples is always greater than 4 (i.e. presence of interstitial oxygen) whereas for the reduced sample y becomes equal to or smaller than 4 only when x is 0.15 or greater. This is the range of Ce content for which the material superconducts. For a material with Ce x=0.15 the superconducting properties can be varied reversibly by changing the oxygen content. In addition, we propose that the oxygen in these materials can be either ordered or disordered, thereby affecting the transport properties. Platelet-like crystals of Nd2-xCexCuOy with x=0 to 0.18, have been grown via a flux technique. Those having a Ce content between 0.14 and 0.17 are superconducting with the sharpest transitions (Tc = 21 ± 1K) for x = 0.14. Metallic-like behavior above Tc, with a linear temperature dependence above 150K was observed on all the crystals. Below 30K, the in-plane resistivity is independent of T. The Hall coefficient is sensitive to processing conditions but is usually negative above 100K. The upper critical field with field along the c-axis is 6T at 4.2K.

Original languageEnglish (US)
Pages (from-to)285-290
Number of pages6
JournalPhysica C: Superconductivity and its applications
Volume162-164
Issue numberPART 1
DOIs
StatePublished - Dec 1989
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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