Structural changes and microstructures of Ba1-xSrxAl2O4 for 0 < x < 0.4
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.
KeywordsTrydimyte structure BaAl2O4 Diffuse scattering
Unable to display preview. Download preview PDF.
- C. Xie, Q. Zeng, D. Dong, S. Gao, Y. Cai and A. R. Oganov, Phys. Lett. A (in press).Google Scholar
- H. T. Stokes, C. Sadate, D. M. Hatch, L. L. Boyer and M. J. Mehl, Phys. Rev. B 65, 064105 (2002).Google Scholar
- J. M. Perez-Mato, R. L. Withers, A-K. Larsson, D. Orobengoa and Y. Liu, Phys. Rev. B 79, 064111 (2009).Google Scholar
- K. Hammonds, M. Dove, A. Giddy, V. Heine and B. Winkler, Am. Mineralogist 81, 1057 (1996).Google Scholar
- M. K. Gupta, R. Mittal and S. L. Chaplot, Chinese J. of Phys. 49, 316 (2011).Google Scholar
- U. Rodehorst, M. A. Carpenter, S. Marion and C. M. B. Henderson, Mineralogical Mag. 67, 989003.Google Scholar
- S. Niyomwas, T. Sathaporn and S. Singarothai, Marer. Sci. and Engin. 18, 072001 (2011).Google Scholar
- E. Tanaka, Y. Ishii, H. Tsukasaki, H. Taniguchi and S. Mori, J. Jpn. Appl. Phys. 53, 09PB01 1–4 (2014).Google Scholar
- V. Petricek, M. Dusek and L. Palatinus, Jana2006. The Crystallographic Computing System (Institute of Physics, Prague, 2006).Google Scholar
- Y. Ishii, E. Tanaka, H. Tsukasaki and S. Mori (in preparation).Google Scholar