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by high-energy X-ray diffractionYoneda, Yasuhiro; Ohara, Koji*; Nagata, Hajime*
no journal, ,
KNbO has been a candidate for the end member of a non-Pb ferroelectric materials. We performed local structure analysis of KNbO bulk ceramics by high-energy synchrotron X-ray measurements. It has recently established that temperature-driven structural phase transitions in several perovskite ferroelectric materials (PbTiO, BaTiO, and NaNbO) believed to be purely displacive, have a significant order-disorder component. We performed the local structure analysis in a wide-temperature range to observe order-disorder feature of KNbO. The lowest temperature structure of KNbO is rhombohedral, and we found that the local rhombohedral distortion maintained in the high-temperature cubic phase.
Yoneda, Yasuhiro; Ohara, Koji*
no journal, ,
Atomic pair-distribution function (PDF) is one of the local structure analysis techniques. In SPring-8, one can be performed PDF measurements at bending magnet beamlines owing to its high critical energy. We performed a round robin test by using two bending magnet beamlines for PDF analysis. We concluded that the same data sets can be obtained from both beamlines for the conventional local structure analysis. On the other hand, the results of Rietveld analysis are different owing to the resolution of the incident X-ray beam.