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Persistent URL http://purl.org/net/epubs/work/37180
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Record Id 37180
Title Neutron diffraction study of quenched Li0.3La0.567TiO3 lithium ion conducting perovskite
Abstract The Li+ ion conductor Li0.3La0.567TiO3 was synthesized as a metastable phase quenched in liquid N-2 from 1300 degrees C, and it was studied by time-of-flight powder neutron diffraction at high-resolution (HRPD instrument, ISIS Facility, U.K.). At room temperature a tetragonal perovskite superstructure was found, with a root 2a(p) x root 2a(p) x 2a(p) unit cell (a = 5.48027(1), c = 7.75591(2) angstrom, and Z = 4), I4/mcm space group, and a(0)a(0)c(-) tilt system of the TiO6 octahedra. Superlattice hkl reflections with odd l were systematically weaker and broader. By Fourier difference maps, the Li atom was located in a disordered position inside the La vacancy hollow, close to the bottleneck site at the center of the Ti4O4 square window. The Rietveld refinement convergyed to R-p = 6.56%, R-Bragg(even l) = 3.26%, and R-Bagg(odd l) = 11.6%. A two-dimensional pathway of Li+ ion mobility inside the structure, based on the coupled ordering of lithium and lanthanum, is proposed. At about 600 degrees C the unit cell transforms into a(p) x a(p) x a(p), with a disappearance of superlattice reflections. A tetragonal pseudo-cubic P4/mmm structure (a = 3.89644(1), c = 3.89748(2) angstrom, and Z = 1) was found (T = 650 degrees C) and Rietveld refined to R-p = 6.10% and R-B = 4.86%. Lithium was located on the layer of Ti atoms rather than on that of La as in the room-temperature structure.
Organisation CCLRC , ISIS , ISIS-HRPD
Keywords ISIS 2006
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Language English (EN)
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Journal Article Chem Mater 18, no. 9 (2006): 2411-2417. doi:10.1021/cm060120r 2006