Cooperative Tilting Scheme of VFi6 Octahedra Related to the Structural Phase Transitions of Diluted Layer Compound Cs0.5Rb0.5VF4
✍ Scribed by Hidaka, M. ;Akiyama, H. ;Hidaka, A. ;Wanklyn, B.M.
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 260 KB
- Volume
- 177
- Category
- Article
- ISSN
- 0031-8965
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✦ Synopsis
The successive structural phase transitions of the diluted layer compound Cs 0.5 Rb 0.5 VF 4 are studied by means of polarized light scattering and X-ray diffraction. It is found that the structural transitions occurring at about 123 and 368 K are mainly characterized by the cooperative tilting of VF 6 octahedra around [100], [010] and [001] axes in the two-dimensional networks of the octahedra. The space group in each phase is determined as follows; D 3 2 -P2 1 2 1 2 in Phase IV (T 123 K), D 13 2h -Pmmm in Phase III (123 K T 368 K), and D 5 4h -P4/mbm in Phase II (368 K T), on heating. The structure is determined at room temperature by using a four-circle X-ray diffractometer. The following tilting scheme of the VF 6 octahedra characterizes the structural phase transition of Cs 0.5 Rb 0.5 VF 4 ; a p b p c p (Phase IV) 3 a p a p c p (Phase III) 3 a 0 a 0 c p (Phase II) 3 a 0 b 0 c 0 (Phase I).