Decrease of interlamellar spacing of silica samples induced by external pressure

Lamellar silica and cadmium or mercury derivative-doped samples were synthesized by neutral amine route through the sol–gel process. These samples showed a decrease of the interlamellar d-space promoted only by an increase of the externally applied pressure on the samples. For a constant external pressure the observed decrease has a linear behavior as a function of time. The undoped lamellar silica, when pressed under 760 mPa for 45 min, exhibited a decrease of the interlamellar distance of 16%. The obtained results suggested that under an increased external pressure, cadmium is forced to change its coordination environment, to adjust to a most stable structure.