A study of the upper limit of borate substitution in LnSr2Cu3-xBxO7

JP Chapman, Wuzong Zhou, JP Attfield

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4 Citations (Scopus)

Abstract

Compositions LnSr(2)Cu(3-x)B(x)O(7) (Ln=Y, La, Nd, Gd, Yb) have been investigated at 1000 degrees C. Almost single phase samples are obtained for Ln=Gd and Y up to x approximate to 0.8. Powder X-ray structure refinement for a nominal YSr2Cu2.25B0.75O7 sample shows the basic cell to be orthorhombic Pmmm; a=3.8176(2) Angstrom, b=3.8345(2) Angstrom, c=10.9708(5) Angstrom, but electron microscopy shows a well-defined 4Cu:1B ordering in the chain sites producing an ax5bx2c supercell. This confirms that the upper limit of borate substitution is n=0.8. The oxygen contents of the x=0.8 materials can be increased slightly by annealing, but they are not superconducting due to low hole concentrations within the copper oxide sheets. (C) 1997 Elsevier Science S.A.

Original languageEnglish
Pages (from-to)187-191
JournalJournal of Alloys and Compounds
Volume261
Issue number1-2
DOIs
Publication statusPublished - Sept 1997

Keywords

  • borate
  • powder x-ray diffraction
  • high resolution electron microscopy
  • HIGH-PRESSURE SYNTHESIS
  • MODULATED STRUCTURE
  • OXIDE
  • YSR2CU2.5B0.5OY
  • SUPERCONDUCTOR

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