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

Research output: Contribution to journalArticle

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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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microstructure
transition temperature
modulation

Keywords

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

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

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

In: Journal of the Korean Physical Society, Vol. 66, No. 9, 18.05.2015, p. 1355-1358.

Research output: Contribution to journalArticle

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, vol. 66, no. 9, pp. 1355-1358. https://doi.org/10.3938/jkps.66.1355
Tanaka, E. ; Ishii, Y. ; Tsukasaki, H. ; Mori, S. ; Osada, M. ; Taniguchi, H. ; Sato, Y. ; Kubota, Y. / 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. In: Journal of the Korean Physical Society. 2015 ; Vol. 66, No. 9. pp. 1355-1358.
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AU - Ishii, Y.

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AU - Sato, Y.

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AB - We have investigated the structural changes and the microstructures of Ba1-xSrxAl2O4 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 Ba1-xSrxAl2O4 for 0 < x < 0.4 reveal that BaAl2O4 should be characterized as a modulated structure with triple-q modulation vectors along the <110> directions and on the other hand, Ba1-xSrxAl2O4 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 Sr2+ for Ba2+ should suppress a structural instability due to the AlO4 tetrahedral network and decrease the structural phase transition temperature.

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