The effect of different plasma gas environments on vermiculite layer

Vermiculite was treated with argon, air, water vapour and hydrogen radio frequency plasmas at room temperature for few minutes. As a general rule, plasma gasses induced various layer modifications. Chemical analyses evidenced a significant decrease in the interlayer cation content, especially for hydrogen and water vapour treated specimens. X-ray diffraction showed both a decrease of peak intensity and a halving of (001) reflection, thus suggesting the formation of layer defects along the layer stacking direction and onto (00l) planes as well. Thermal analysis showed modifications of the temperature-activated reactions induced by the plasma treatments. Finally Fourier Transformed Infra-Red spectroscopy (FTIR) showed that different bonding of H2O occurred after the treatment, in particular for vermiculite treated with hydrogen plasma.