Modulated phases of LiTISO4
| Autor: | Hironobu Kasano, Yukihiko Kawamura, Shirou Tsuchiyama, Hiroyuki Mashiyama |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Ferroelectrics. 217:121-128 |
| ISSN: | 1563-5112 0015-0193 |
| DOI: | 10.1080/00150199808015029 |
| Popis: | The structurally modulated phases in LiTlSO4 single crystal are investigated by means of X-ray diffraction. The crystal structure of Phase I in LiTlSO4 was decided to be isomorphous to that of Phase I (normal phase, space group Pmcn, Z = 4) in LiRbSO4 and LiNH4SO4 by X-ray structural analysis at 320 K. It was found that the satellite reflections with the modulation wavenumber q ∼ 0·3 a * appeared in Phase II’(298–267 K) on a cooling run. In Phases II(267–250 K) and III (below 250 K), the modulation wavenumbers were assigned as q = 1/4a * and q = 1/6a * + 1/2b *, respectively. The unit cell volumes of Phases II and III were four times and six times larger than that of Phase I, respectively. It was also found that Phase II did not appear on a heating run from Phase III. The ratio b/a of the basic unit cell size was 1·732 in Phase III as if it were a hexagonal system. |
| Databáze: | OpenAIRE |
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