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 on X-ray powder diffraction data indicate that in Tb and Dy titanate pyrochlores, 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). In all of these Ln-Ti-O pyrochlores, the addition of magnetic Ln3+ in place of nonmagnetic 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.
@article{arxiv.cond-mat/0603735,
title = {Stuffed Rare Earth Pyrochlore Solid Solutions},
author = {G. C. Lau and B. D. Muegge and T. M. McQueen and E. L. Duncan and R. J. Cava},
journal= {arXiv preprint arXiv:cond-mat/0603735},
year = {2009}
}
Comments
25 pages, 7 figures, submitted to J. Solid State Chem