Interstitial anions in the T* structure

P. Lightfoot*, Shinyou Pei, J. D. Jorgensen, X. X. Tang, A. Manthiram, J. B. Goodenough

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Rietveld refinement of powder neutron diffraction data has been used to locate the excess anions in the T* phase La1.25Dy0.75CuO3.75F0.5. The structure is orthorhombic, Cmma, a=5.4609(1), b=5.5089(1), c=12.4842(2) A ̊ and Z=4. The excess anion content is incorporated as an interstitial defect in the La2O2 rocksalt layers analogous to the defect identified in La2NiO4.18. Data on the stoichiometric T* phase La1.25Dy0.75CuO4, P4/nmm, a=3.8661(1) and c=12.4475(2) A ̊ show that the tetragonal structure is retained to 10 K. Both structures show complete ordering of the Dy into the fluorite layers of the T* structure. An inability to distinguish between O and F in the refinement leaves unresolved the driving force for the orthorhombic distortion; it does not appear to be due to a cooperative tilting of the CuO5-xFx square pyramids.

Original languageEnglish
Pages (from-to)15-22
Number of pages8
JournalPhysica C: Superconductivity and its applications
Issue number1-2
Publication statusPublished - 15 Jul 1990


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