X-ray studies of interlayer water absorption and mesoporous water transport in a weakly hydrated clay.

摘要: The swelling of layered smectite clay particles consists a change in the interlayer repetition distance ($d$-spacing) as function temperature and humidity. For synthetic sodium fluorohectorite, hydrodynamically stable hydration states with zero, one two intercalated monolayers water have previously been reported, discrete jumps $d$-spacing at transitions between states. Keeping fixed varying ambient relative humidity, we find small reproducible changes also within These are monotonous order magnitude smaller than shift that is typical transition reproducibility reliability this humidity controlled $d$-shift enables us to use $d$ measure local surrounding particles. We provide an example application observation: imposing gradient over quasi-one-dimensional temperature-controlled sample, using x-ray diffraction record $d$-spacing, able extract profiles along sample length. Their time evolution describes transport through mesoporous space inside clay. An analysis measured based on Boltzmann transformation, under certain simplifying assumptions, yields diffusive behavior either normal or possibly weakly anomalous.