Abstract
The identity of the pyrochlore phase seen during the synthesis of ferroelectric Bi4-xLnxTi3O12 Aurivillius oxides is shown to be Bi2/3Ln4/3Ti2O7. This pyrochlore is only stable for Ln3+=Sm3+ or smaller. For larger lanthanides the layered Aurivillius oxide is favoured. The presence of six-fold disorder, associated with the Bi 6s2 lone pair electrons, is believed to stabilise the unexpected stoichiometry of this oxide. Precise structures, obtained by Rietveld refinement from synchrotron X-ray diffraction data, of three examples Ln3+=Eu, Ho and Yb are presented.
| Original language | English |
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| Pages (from-to) | 836-840 |
| Number of pages | 5 |
| Journal | Journal of Solid State Chemistry |
| Volume | 182 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Apr 2009 |