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Long- and short-range order in stuffed titanate pyrochlores |
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| Authors: | GC Lau TM McQueen HW Zandbergen |
| Institution: | a Department of Chemistry, Princeton University, Princeton, NJ 08544, USA b NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899, USA c Department of Materials Science, Delft University of Technology, Rotterdamseweg 137, 2682 AL Delft, The Netherlands |
| Abstract: | We report a structural study of the stuffed pyrochlore series Ln2(Ti2−xLnx)O7−x/2 (Ln=Ho, Yb; 0?x?0.67). Electron microscopy and Rietveld refinements of neutron powder diffraction data for the x=0.67 end members, Ho2TiO5 and Yb2TiO5, reveal that small domains (∼50 Å or less) exist where the Ln and Ti/Ln sublattices are pyrochlore like, while the average structure is fluorite like. Both the Ho and Yb stuffed pyrochlore series for 0.1?x?0.5 are shown to be a composite of long- and short-range-ordered pyrochlore phases. The relative fraction of long-range vs. short-range pyrochlore order decreases with increasing Ln doping. An additional complex structural modulation of the pyrochlore structure is observed in electron diffraction and high-resolution electron microscopy images. |
| Keywords: | Pyrochlore Stuffed pyrochlore Stuffed spin ice Geometrically frustrated magnet Pyrochlore to fluorite solid solution Rare-earth titanate |
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