Structural changes and microstructures of Ba<inf>1-x</inf>Sr<inf>x</inf>Al<inf>2</inf>O<inf>4</inf> for 0 < x < 0.4

E. Tanaka, Y. Ishii, H. Tsukasaki, S. Mori, M. Osada, H. Taniguchi, Y. Sato, Y. Kubota

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Abstract

We have investigated the structural changes and the microstructures of Ba<inf>1-x</inf>Sr<inf>x</inf>Al<inf>2</inf>O<inf>4</inf> for 0 < x < 0.4 by using transmission electron microscope (TEM) and synchrotron radiation powder X-ray diffraction experiments. The TEM experiments revealed the existence of a structural phase boundary at approximately x = 0.1, at which the superlattice reflection spots at the 1/2 0 0 -type positions change into diffuse streaks along three equivalent <110> directions in the hexagonal structure. In addition, real-space images of Ba<inf>1-x</inf>Sr<inf>x</inf>Al<inf>2</inf>O<inf>4</inf> for 0 < x < 0.4 reveal that BaAl<inf>2</inf>O<inf>4</inf> should be characterized as a modulated structure with triple-q modulation vectors along the <110> directions and on the other hand, Ba<inf>1-x</inf>Sr<inf>x</inf>Al<inf>2</inf>O<inf>4</inf> for 0.1 < x < 0.4 be characterized as an intermediate (precursor) state with a rigid unit mode due to structural instability. These experimental results implied that the partial substitution of Sr<sup>2+</sup> for Ba<sup>2+</sup> should suppress a structural instability due to the AlO<inf>4</inf> tetrahedral network and decrease the structural phase transition temperature.

Original languageEnglish
Pages (from-to)1355-1358
Number of pages4
JournalJournal of the Korean Physical Society
Volume66
Issue number9
DOIs
Publication statusPublished - 2015 May 18
Externally publishedYes

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Keywords

  • BaAl<inf>2</inf>O<inf>4</inf>
  • Diffuse scattering
  • Trydimyte structure

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Tanaka, E., Ishii, Y., Tsukasaki, H., Mori, S., Osada, M., Taniguchi, H., Sato, Y., & Kubota, Y. (2015). Structural changes and microstructures of Ba<inf>1-x</inf>Sr<inf>x</inf>Al<inf>2</inf>O<inf>4</inf> for 0 < x < 0.4. Journal of the Korean Physical Society, 66(9), 1355-1358. https://doi.org/10.3938/jkps.66.1355