An Electron Diffraction Study of Short-Range Order in the (1−x)Bi2O3·xCaOγ-Type Solid Solution and Its Relationship to Low-Temperature Ca4Bi6O13
✍ Scribed by Ann-Kristin Larsson; Ray Withers
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 721 KB
- Volume
- 135
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The body centered cubic (a& &4.26 A s s ) -type solid solution (ss ) phase (1؊x)Bi 2 O 3 • xCaO (& &0.50 < x <& &0.60 at & &820°°C) was investigated by electron diffraction. Instead of finding evidence for additional Bragg reflections at G$ $a* as previously assumed attempting to interpret powder neutron diffraction data (Gruber et al., J. Solid State Chem. 108,[250][251][252] 1994), localized diffuse scattering was detected and described by G$ $q, where q+ +0.21 12112 2* is a (diffuse) modulation wave vector. A crystal structural relationship between the cation arrays in the ss phase and the low-temperature line phase, Ca 4 Bi 6 O 13 (LT), was established. The unit cell of the LT phase can be expressed as
From the cation ordering in the LT phase and the reciprocal space relation 2b* LT ؍ 0.21 112 12 2* + +q, the localized diffuse scattering in the ss phase was linked to cation ordering into layers perpendicular to 1 112 12 2 .