Synchrotron based transmission x-ray microscopy reveals smectite fine structure in an aqueous environment

The unusual behaviour of smectites, the ability to change volume when wetted (swelling) or dried (shrinking), make soil containing smectites very unstable and hazardous for the building industry due to foundation movement and poor slope stability. These macroscopic properties are dominated by the structural arrangement of its finest fraction. In this work we show utilisation of a new technique called transmission x-ray microscopy (TXM) based on the synchrotron photon source. This technique enables, for the first time, the study in three dimensions, of smectite gel arranged in voluminous cellular structure and it modification by adding Al13 Keggin macro-molecule [Al13(O)4(OH)24(H2O)12] 7+ . All these observations were conducted in the natural aqueous environment.