Stuffed rare earth pyrochlore solid solutions |
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Authors: | G.C. Lau B.D. Muegge T.M. McQueen E.L. Duncan R.J. Cava |
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Affiliation: | Department of Chemistry, Princeton University, Princeton, NJ 08544, USA |
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Abstract: | Synthesis and crystal structures are described for the compounds Ln2(Ti2−xLnx)O7−x/2, where Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and x ranges from 0 to 0.67. Rietveld refinements of X-ray powder diffraction data indicate that in the Tb and Dy titanate pyrochlores, the extra Ln3+ cations mix mainly on the Ti4+ site with little disorder on the original Ln3+ site. For the smaller rare earths (Ho-Lu), stuffing additional lanthanide ions results in a pyrochlore to defect fluorite transition, where the Ln3+ and Ti4+ ions become completely randomized at the maximum (x=0.67). Initial magnetic characterization for the fully stuffed x=0.67 samples for Ln=Tb-Yb shows no long range ordering down to 2 K, and only partial saturation of the full expected magnetic moment under applied fields up to 5 T. In all of these Ln-Ti-O pyrochlores, the addition of magnetic Ln3+ in place of non-magnetic Ti4+ adds edge sharing tetrahedral spin interactions to a normally corner sharing tetrahedral network of spins. The increase in spin connectivity in this family of solid solutions represents a new avenue for investigating geometrical magnetic frustration in the rare earth titanate pyrochlores. |
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Keywords: | Pyrochlore Stuffed pyrochlore Stuffed spin ice Geometrically frustrated magnet Pyrochlore to fluorite solid solution Rare earth titanate |
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