Structural and thermal characterization of the γ″ polymorph of Bi2MoO6

Among the different polymorphic phases of the Bi₂MoO₆ system, the intermediate γ″ compound has been characterized within a metastable state by high temperature X-ray diffraction and Raman spectroscopy. The transition γ ? γ″ is found to be partially displacive and partially reconstructive. In the context of the ferroelectricity of γ, the nature of the paraelectric phase is discussed with the help of space group considerations and Buerger's theory of phase transitions.