Phonon properties of nanosized bismuth layered ferroelectric material—Bi2WO6

Nanosized Bi₂WO₆ was synthesized by a mild hydrothermal crystallization process. This method allowed obtaining plate‐like crystallites of very small thickness (down to 3 nm). The effect of particle size on the structure and properties of Bi₂WO₆ was studied by X‐ray diffraction (XRD), transmission electron microscopy, and Raman and infrared spectroscopies. It has been shown that the orthorhombic distortion decreases with decreasing particle size, but the structure of the smallest crystallites is still orthorhombic. Raman studies have also revealed a very strong intensity decrease for those modes that appear mainly for incident and scattered light polarized perpendicular to the layers. This behavior has been attributed to a decrease in the orthorhombic distortion and a plate‐like shape of the nanocrystallites. Copyright © 2009 John Wiley & Sons, Ltd.