Abstract
Samples of the complex osmates Ca2Os2O7, Tl2Os2O7 − x and Pb2Os2O7 − x have been obtained by direct reaction of the component oxides in sealed tubes. The structures and compositions of these materials have been investigated by powder neutron and X-ray diffraction at room temperature and through variable temperature studies. Ca2Os2O7 adopts a stoichiometric, orthorhombic weberite structure but the distortion of the OsO6 octahedra and eightfold Ca–O co-ordinations decrease with increasing temperature indicating that this material lies close to the weberite/pyrochlore phase boundary. The lead and thallium phases adopt oxygen deficient, cubic pyrochlore structures under the synthesis conditions employed though no evidence was found of cation non-stoichiometry. Preliminary measurements of the electronic properties of weberite Ca2Os2O7 are also reported and discussed in comparison with the lead, thallium, cadmium and mercury osmate pyrochlores.
Original language | English |
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Pages (from-to) | 2376-2382 |
Journal | Journal of Materials Chemistry |
Volume | 12 |
Issue number | 8 |
DOIs | |
Publication status | Published - 1 Aug 2002 |