Crystal structure of thermoelectric compound [Bi1.79Sr 1.98Oy]0.63RhO2

Kunio Yubuta, Satoshi Okada, Yuzuru Mlyazaki, Ichiro Terasaki, Tsuyoshi Kajitani

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17 Citations (Scopus)

Abstract

We have studied the crystal structure of the misfit-layered crystal Bi 1.91Sr2Rh1.77Ox by electron diffraction and high-resolution electron microscopy. This compound consists of two interpenetrating subsystems of a RhO2 sheet and a distorted four-layered rock-salt-type (Bi,Sr)O block. Both subsystems have common a-axes, c-axes, and β-angles with a = 5.28 Å, c = 29.77 Å, and β = 93.7°. On the other hand, the crystal structure is incommensurated parallel to the b-axis, b1 = 3.07 Å for the RhO2 sheet and b 2=4.88 Å for the (Bi,Sr)O block. The axis ratio, b1/b2∼0.63, characterizes the structural analogue as [Bi 1.79Sr1.98Oy]0.63[RhO2]. This compound has two modulation vectors, q1 = a* + 0.63b 1* and q2 = 0.17b1* + c*, and the superspace group is assigned as the Cc(1 β0, 0μ1) type from electron diffraction patterns. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly exhibit modulated displacive as well as compositional atomic arrangements. A tentative structure model has been proposed, and the calculated image reproduces observed characteristic features reasonably well.

Original languageEnglish
Pages (from-to)8557-8561
Number of pages5
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume44
Issue number12
DOIs
Publication statusPublished - 2005 Dec 8

Keywords

  • Electron diffraction
  • High-resolution image
  • Misfit-layered structure
  • Modulated structure
  • Superspace group

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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