Study of the dehydration process of uranyl difluoride hydrates stable under usual conditions of temperature, pressure and atmospheric moisture

The dehydration of the uranyl difluoride hydrate stable under usual conditions of temperature, pressure and atmospheric moisture has been investigated by controlled transformation rate thermal analysis, controlled thermogravimetry and by variable temperature X-ray diffraction under controlled atmosphere. The importance of the residual water vapor above the sample has been demonstrated. It was possible to distinguish three steps in the dehydration of uranyl difluoride hydrate. These steps are: the dehydration of the solid solution usually named β, the transformation of β to the usually named α, and the loss of water from phase α. The range of existence of the two solid solutions α and β have been defined.