Synthesis and phonon properties of nanosized Aurivillius phase of Bi2MoO6

Nanosized crystallites Bi₂MoO₆ of a platelet shape were synthesized by a mild hydrothermal crystallization process. The effect of particle size on the structure and properties of Bi₂MoO₆ was studied by X‐ray diffraction, transmission electron microscopy, as well as Raman and infrared (IR) spectroscopies. Moreover, temperature‐dependent Raman spectra were collected for bulk and nanocrystalline Bi₂MoO₆. These studies showed that the thickness of the smallest crystallites is about 8–11 nm. Raman and IR studies have revealed that the damping and the intensity of Raman and IR bands are significantly modified with decreasing particle size and temperature. Moreover, some bands experience significant shifts both towards lower and higher wavenumbers. The obtained results indicate that, similar to the isostructural Bi₂WO₆, the orthorhombic distortion decreases with decreasing particle size. However, the structure of nanocrystalline Bi₂MoO₆ remains orthorhombic and noncentrosymmetric, and the structural changes are not the same as those observed in Bi₂WO₆. Copyright © 2010 John Wiley & Sons, Ltd.