Local oxygen octahedra rotations in Ba1-xKxBiO3 and BaBiO3

Y. Yacoby, S. M. Heald, E. A. Stern

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

We report XAFS investigations of BaBiO3 and Ba0.6K0.4BiO3 in the temperature range from 10 K to 300 K extending out to fourth nearest neighbours. The results show that in both systems the local structure differs substantially from the average structure determined by neutron diffraction measurements. At temperatures up to at least T = 80 K the local oxygen octahedra rotations in BaBiO3 have in addition to the [1 1 0] component a disordered rotation component about the [0 0 1] axis. To within the experimental accuracy the local rotation components about the [1 0 0], [0 1 0] and [0 0 1] axes are equal. The results in superconducting Ba0.6K0.4BiO3, are consistent with oxygen octahedra rotations either around [1 1 1] or [1 1 0] type axes. If the rotation is assumed to be about [1 1 1] type axes, the rotation angles are 4.5° up to at least T = 220 K. This local rotation exists in spite of the fact that the crystal is on the average cubic at all temperatures. A theoretical study of the effect of these random rotations on the superconducting properties of Ba1-xKxBiO3 may be of interest.

Original languageEnglish
Pages (from-to)801-806
Number of pages6
JournalSolid State Communications
Volume101
Issue number11
DOIs
StatePublished - Mar 1997
Externally publishedYes

Keywords

  • A. high-T superconductors
  • A. superconductors
  • B. EXAFS
  • C. order-disorder effects

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