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Crystallography and Crystal Chemistry of (Ba1-xSrx)2TiO4

Published

Author(s)

Winnie Wong-Ng, James A. Kaduk, Debra L. Kaiser, Julia Frank

Abstract

This paper reports an investigation of the homogeneity range, crystal chemistry and crystallography of a technologically-important (Ba2-xSrx)TiO4 solid solution series. Since the end members of the series - Ba2TiO4 (Pnma (No.62)) and Sr2TiO4 (I4/mmm (No. 139)) - have totally different crystal structures, a complete solid solution of (Ba2-xSrx)TiO4 was not expected or observed. The structure of orthorhombic (Ba2-xSrx)TiO4 consists of TiO4 tetrahedra interconnected by barium cations. Contrary to literature reports, among the orthorhombic members in the (Ba2-xSrx)TiO4 series two different structures were established based on synchrotron data for (Ba1.25Sr0.75)TiO4. While the space group of the composition with 0 x 0.5 is Pnma, the space group for 0.5 < x 1.30 is Pna21 (No. 33). In the Pna21 structure, the twist angles between two tetrahedra as viewed along the a-axis increase progressively as the Sr concentration increases. There appears to be a limit to these twist angles, beyond which the stability of the Pna21 structure is no longer maintained. The approximate maximum x in (Ba2-xSrx)TiO4 is 1.3. A miscibility gap was found between (Ba0.7Sr1.3)TiO4 and tetragonal Sr2TiO4.
Citation
Acta Crystallographica Section B-Structural Science

Keywords

(Ba<sub>1-x</sub>Sr<sub>x</sub>)2TiO<sub>4</sub>, crystal chemistry, miscibility gap, Reitveld refinements, structure

Citation

Wong-Ng, W. , Kaduk, J. , Kaiser, D. and Frank, J. (2017), Crystallography and Crystal Chemistry of (Ba<sub>1-x</sub>Sr<sub>x</sub>)2TiO<sub>4</sub>, Acta Crystallographica Section B-Structural Science (Accessed April 13, 2024)
Created February 19, 2017