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Yoneda, Yasuhiro; Takeda, Hiroaki*; Tsurumi, Takaaki*
JPS Conference Proceedings (Internet), 1, p.012103_1 - 012103_4, 2014/03
BiWO is the simplest member of the Aurivillius family of (BiO)(ABO) with one oxygen octahedron sandwiched between two BiO layers (m=1). We report the high-energy synchrotron X-ray diffraction study of ferroelectric BiWO at low temperatures, and a new phase transition was found around 200 K. The mechanism of this phase transition was examined by atomic pair-distribution function (PDF) method.
Yoneda, Yasuhiro; Kohara, Shinji*; Takeda, Hiroaki*; Tsurumi, Takaaki*
Japanese Journal of Applied Physics, 51(9), p.09LE06_1 - 09LE06_6, 2012/09
Times Cited Count:15 Percentile:51.2(Physics, Applied)Local structure analysis of BiWO was performed by high-energy X-ray atomic pair-distribution function (PDF) analysis. We found a deviation between local and average structures owing to the different coherence length between BiO and WO layers. Bi atoms were displaced toward the -axis of the orthorhombic structure. The local off-center shift of Bi atoms coupled with thermal factor and negrected in the average structure. The coherence length of BiO layer increased with increasing temperature and splead in the whole crystal when the average structure changed from to structure.
Yoneda, Yasuhiro; Kohara, Shinji*; Han, J. S.*; Takeda, Hiroaki*; Tsurumi, Takaaki*
no journal, ,
BiWO of a bismuth layered compound is expected as non-lead system ferroelectric. The Curie point is in about 1000C. Therefore, it was thought that it became possible to synthesize below the Curie point, and the sample of a single domain was obtained easily in crystal breeding by the flux method and the thin film making by the PLD method. However, a lot of observations not thought about were found with a single domain as for the BiWO crystal actually made. Then, it is a purpose of this experiment to perform high-temperature X-ray diffraction of BiWO, and to verify the phase transition system again. As a result of the experiment, it has been understood that additional structural phase transition exists also below the Curie point. The domain configuration changes by the existence of another phase transition caused during cooling afterwards even if the crystal is promoted below the Curie point at the high temperature.