Determination of the Space Group of Ceramic BaO.Pr2O3.4TiO2 by Electron Diffraction
- 1 October 1995
- journal article
- Published by International Union of Crystallography (IUCr) in Journal of Applied Crystallography
- Vol. 28 (5) , 577-581
- https://doi.org/10.1107/s0021889895004365
Abstract
Ceramic specimens of BaO.Pr203 .4TiO2 (Ba4.5Pr9Ti18O54) were prepared by the mixed-oxide route. Electron diffraction indicated that the compound has orthorhombic symmetry with cell parameters a ≃ 22.2, b ≃ 12.2 and c ≃ 7.6 Å. The space group was identified as Pnam, one of the two possible space groups previously identified for Ba3.75Ln9.5Ti18O54, where Ln = Nd, La or Sm. The fact that Pnam is a subgroup of the 2c superlattice of Pbam and the existence of antiphase domains with a displacement vector c/2 in BaO.Pr2O3 .4TiO2 suggests that it underwent a phase transition during cooling from Pbam to Pnam in which the c axis doubled.Keywords
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