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Structures and phase diagram for the system CaTiO3-La2/3TiO3 |
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| Authors: | Zhaoming Zhang Gregory R. Lumpkin Christopher J. Howard Karl R. Whittle Keiichi Osaka |
| Affiliation: | a Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia b Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK c ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK d Department of Engineering Materials, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK e Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan |
| Abstract: | High-resolution neutron and synchrotron X-ray powder diffraction have been used to examine various compositions across the system (1−x)CaTiO3−xLa2/3TiO3. The structures at room temperature were determined according to composition: in Pbnm for 0?x?0.5, Ibmm for 0.5<x<0.7, then I4/mcm for 0.7?x<0.9, and finally in Cmmm for x?0.9. Although the four structures are the same as those proposed previously in an X-ray diffraction study, the phase boundaries are somewhat different, in particular the Pbnm↔Ibmm phase boundary has been extended from x?0.4 to x>0.5 in the current study based on our high-resolution neutron diffraction data. From in situ measurements to identify structures above room temperature, an approximate composition-temperature phase diagram has been constructed, involving four temperature-induced phase transitions: Pbnm→I4/mcm, Ibmm→I4/mcm, I4/mcm→Pm3¯m and Cmmm→P4/mmm. |
| Keywords: | Perovskites Crystal structures Octahedral tilting Cation/vacancy ordering Phase diagram Neutron powder diffraction Synchrotron X-ray diffraction |
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