How do the useful and interesting properties of clays come about?
In practice it is the interactions with water, which occur both on the scale of the crystal structure and on that of the micron-sized particles. Our aim is to understand how the hydration and solvation mechanisms interrelate to affect the properties of the clays. To do this, we use synchrotron x-ray diffraction while controlling the sample environment. The silicate lamellae of swelling clays are bound together by cations which permit water to enter the interlayer space (see figure at top). This microscopic intercalation increases the c lattice constant, which can be directly measured by x-ray diffraction. However, clays form plate-shaped micron-scale particles. Because of this morphology, bulk clays are porous, and so hydration necessarily also depends upon the percolation of water through the material. It has not always been easy to distinguish these two mechanisms in bulk hydration studies so far.
