Crystal structures and phase transitions in a-site deficient perovskites Ln1/3TaO3
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Date
2008-11-11
Journal Title
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Publisher
American Chemical Society
Abstract
The synthesis and structures of the perovskites Ln1/3TaO3 are described. As the size of the Ln cation is reduced, the compounds display a sequence of structure: P4/mmm/La → Cmmm/Ce−Gd → Pmma/Tb, Dy → Pmc21/Ho, Er. Although apparently tetragonal in P4/mmm, electron diffraction patterns of Tm1/3TaO3 reveal this has a complex incommensurate structure. Likewise Gd1/3TaO3 appears metrically tetragonal, but electron diffraction and synchrotron X-ray powder diffraction demonstrate this is actually orthorhombic. The suppression of the spontaneous orthorhombic strain in Gd1/3TaO3 is thought to be due to the proximity to the first-order Cmmm−Pmma transition. Variable temperature studies show both Tb1/3TaO3 and Dy1/3TaO3 undergo a first-order Cmmm−Pmma transition upon heating. © 2008, American Chemical Society
Description
Keywords
Crystal structure, Perovskites, Phase transformations, Electron diffraction, Orthorhombic lattices, Heating
Citation
Zhou, Q. D., Saines, P. J., Sharma, N., Ting, J., Kennedy, B. H., Zhang, Z., Withers, R. L., & Wallwork, K. S. (2008). Crystal structures and phase transitions in a-site deficient perovskites Ln1/3TaO3. Chemistry of Materials, 20(21), 6666–6676. doi:10.1021/cm8014868