Cation distribution and structural instability in Bi4-xLaxTi3O12

Minoru Osada, Masaru Tada, Masato Kakihana, Takayuki Watanabe, Hiroshi Funakubo

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Abstract

Raman spectra of Bi4-xLaxTi3O12 have been investigated. For an increasing degree of La doping, we find a substantial hardening of the vibration involving Bi atoms at the perovskite A site, whereas the Bi mode at the Bi2O2 layer is negligibly changed. From a comparison with a simple mass consideration, we identify a precise cation distribution, which indicates a pronounced site selectivity of La ions for the A site for x < ∼ 1. At room temperature, the lowest mode at 28 cm-1 shows a significant softening with La doping. This behaviour resembles the temperature dependence in the nondoped material (at constant composition). A remarkable correlation is found between the soft-mode frequency and TC for Bi4-xLaxTi3O12. We suggest that this correlation, as well as the soft-mode frequency for substituted materials, offers useful guidelines for designing materials in a controlled manner.

Original languageEnglish
Pages (from-to)5572-5575
Number of pages4
JournalJapanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Volume40
Issue number9 B
Publication statusPublished - 2001 Sep
Externally publishedYes

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Keywords

  • BiLaTiO
  • Cation distribution
  • Phase transition
  • Raman scattering
  • Soft mode

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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