| 摘要 |
<p>The present invention relates to perovskite-type compositions based on tantalum or niobium and, as other constituent element, on an element chosen from the group comprising alkali metals, alkaline-earth metals, transition elements, elements from group Ib and rare-earth metals, and which are characterized in that they show a homogeneity such that the heterogeneity domains are less that or equal to 1 mu m<3>. These compositions are obtained by a process comprising the following stages: - a mixture is prepared comprising, on the one hand, a tantalum oxide sol or a niobium oxide sol and, on the other hand, salts of the other constituent elements of the composition; - the said mixture is dried; - the dried product is calcined. <IMAGE></p> |
