Perovskite-type BaXO3: its structural control by selection of ionic radiusof X

The relationship between the structure of perovskite-type BaXO3 and the ion ic radius of X was investigated. The size of the X ion was controlled by an appropriate combination of a pair of tetravalent ions such as (Ce, Tb), (P r, Tb), (Pr, Zr) and (Tb, Zr). The phases examined were prepared by solid-s olid reaction at 1500 degreesC. Structural characterization was carried out by the powder X-ray diffraction technique. As a result, the change from or thorhombic to a rhombohedral-like structure takes place at 0.0745 nm for X, and another change from rhombohedral-like to a cubic structure occurs at a round 0.0825 nm. These structural characteristics are discussed compared wi th perovskite-type (Nd-x, Sm1-x)AlO3, which shows similar phenomena to BaXO 3. (C) 2001 Elsevier Science B.V. All rights reserved.