Structural phase transitions and mixing behaviour of the Ba-aluminate (BaAl2O4)– Sr-aluminate (SrAl2O4) solid solution

• DOI: 10.1180/0026461036750139
• Publication Date: 2004-01-15T01:54:10Z
• Authors: U. Rodehorst; M. A. Carpenter; S. Marion; C. M. B. Henderson
• Keywords: Superstructure; Monoclinic crystal system; Lattice (music); Lattice constant

Abstract Phase transitions in the BaAl 2 O 4 –SrAl solid solution have been analysed as a function of temperature and composition using infrared (IR) powder absorption spectroscopy. The improper ferroelectric phase transition P 6 3 22 → (2A superstructure) end-member can be detected through change slope wavenumbers hard modes at ∽450 K. A line widths ∽520 K appears to correlate with development diffuse intensity * - b planes electron diffraction patterns reported elsewhere literature. same shift wavenumber is not observed spectra from samples compositions corresponding 60, 80 90% component, but ∽500 has tentatively explained terms different transition, parent structure (√3A product. Strain analysis published high-temperature lattice parameter data suggests that hexagonal monoclinic Sr-rich members may consist two discrete transitions, sequence C 1 suggested. second could related instabilities solution. Autocorrelation IR reveals large positive deviation linear behaviour across solution, which interpreted microscopic strain effects. These strains are probably responsible for transformation shown by