A new model for the description of the structural disorder in natural kaolinite materials is proposed, based on the stacking of two 1:1 layers and their enantiomorphs, and encompassing previously proposed models. The layers, where randomly stacked along the c axis (using probabflistic functions nested in recursive algorithms), correctly describe the observed powder diffraction patterns of natur...

It is surprisingly difficult to freeze water. Almost all ice that forms under "mild" conditions (temperatures > -40 degrees C) requires the presence of a nucleating agent--a solid particle that facilitates the freezing process--such as clay mineral dust, soot or bacteria. In a computer simulation, the presence of such ice nucleating agents does not necessarily alleviate the difficulties associa...

Density functional theory calculations and classical molecular dynamics simulations have been used to investigate the structure and dynamics of water molecules on kaolinite surfaces and confined in the interlayer of a halloysite model of nanometric dimension. The first technique allowed us to accurately describe the structure of the tetrahedral-octahedral slab of kaolinite in vacuum and in inte...

-Dehydration-induced luminescence (DIL), the emission of light from a clay paste upon dehydration, was characterized experimentally for a colloidal kaolinite. The relationship between total photon count of the emitted light and film thickness is linear up to a thickness of 30/~m. The photon emission was obtained over a critical range of water contents (25-60%) of the oven-dry clay, and the kine...

This study focuses on the role played by interparticle and interlayer porosities, preferred orientation of particles water diffusion in dual-porosity clayey media (i.e., swelling clay minerals). For this purpose, we use Na-vermiculite, a that does not exhibit osmotic therefore allows clear discrimination between porosities. Two samples were prepared with an equal proportion porosities 0.25 each...

The mineral fraipontite has been studied by using a combination of scanning electron microscopy with energy dispersive analysis and vibrational spectroscopy (infrared and Raman). Fraipontite is a member of the 1:1 clay minerals of the kaolinite-serpentine group. The mineral contains Zn and Cu and is of formula (Cu,Zn,Al)₃(Si,Al)₂O₅(OH)₄. Qualitative chemical analysis of fraipontite shows an alu...