| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1506391 | Solid State Sciences | 2010 | 8 Pages |
A number of new quaternary rare-earth pyrochlores Ln2BSbO7 are reported with Ln = Pr, Nd, Eu, Gd or Dy, B = Sc, Ga or In. These compositions extend the range of available rare-earth pyrochlores with diamagnetic B-site cations, especially for early lanthanides (Pr, Nd). Rietveld refinements and Mössbauer spectroscopy show that most compounds actually contain a fraction of Sb3+, e.g. have a composition Ln2(B3+1−xSb3+xSb5+)O7. In addition, the rather large size of In3+ induces partial site exchange of Ln and In in Ln2InSbO7 phases. The cell parameters and interatomic distances are in good agreement with those in corresponding Ln2M4+2O7 pyrochlores. Magnetic measurements show dominant antiferromagnetic interactions and the absence of magnetic ordering down to 2 K, as expected in the geometrically frustrated lanthanide sublattice in the pyrochlore structure. Strong crystal field effects are present in all compounds excepted gadolinium ones. The europium magnetism (J = 0) is well described by a Van Vleck behaviour leading to a finite constant magnetic susceptibility at low temperature.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slide
