ABSTRACT
This chapter discusses on the three-component clay-salt-water system. As a continuation of the extensive investigation of the three-component clay-salt-water system, neutron and X-ray diffraction experiments are used to investigate freezing cycles between -5 and +5°C for the model system consisting of butylammonium vermiculite, butylammonium chloride and water. The X-ray diffractometer used was ideal for the investigation, as both the transition from the gel phase to the crystalline phase of the clay and the formation of ice was observed. The temperature where both the freezing transition and the gel-crystalline phase transition occurred was the same in the clay colloid system. Hence, it was concluded to be the ordinary freezing point of the soaking solution. The importance of the butylammonium vermiculite system as a model system for charged colloids lies mainly in the identification of the crystalline, or tactoid, phase with the primary minimum state and the identification of the gel phase with the secondary minimum state.
