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Journal of Materials Science

, Volume 30, Issue 7, pp 1733–1741 | Cite as

Structural and morphological evolution from a freeze-dried precursor to the La1.85Sr0.15 CuO4 superconductor during thermal processing

  • S. A. Alconchel
  • M. A. Ulla
  • E. A. Lombardo
Papers

Abstract

The crystalline phases and morphology of solids with a composition of La1.85Sr0.15CuO4 were studied in terms of thermal processing conditions of freeze-dried acetates. Samples were characterized by X-ray diffraction, scanning electron microscopy and iodometric titration techniques. Results indicate that a full development of the superconducting phase only occurs after pressing sintering and annealing under oxygen of the powders treated at Tf=1253 K for 8 h. The structural evolution observed in this case involves a solid-state reaction between La1.67Sr0.33Cu2O5−δ, La(OH)3 and CuO. The existence of transient liquid phase at temperatures around 600 K generates local composition fluctations (lanthanum deficiency) where the non-superconducting ternary compound La1.67Sr0.33Cu2O5−δ develops. The selection of high heating rates (50 K min−1) below 773 K minimizes the deleterious effect of transient melting and, at the same time, ensures a high reproducibility in the morphology of the final material obtained.

Keywords

Lanthanum Final Material Thermal Processing Structural Evolution Morphological Evolution 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1995

Authors and Affiliations

  • S. A. Alconchel
    • 1
  • M. A. Ulla
    • 1
  • E. A. Lombardo
    • 1
  1. 1.Instituto de Investigaciones en Catálisis y PetroquímicaINCAPE(FIQ, UNL, CONICET)Santa FeArgentina

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