Decrease of interlamellar spacing of silica samples induced by external pressure

Lamellar silica and cadmium or mercury derivative-doped samples were synthe sized by neutral amine route through the sol-gel process. These samples sho wed a decrease of the interlamellar ii-space promoted only by an increase o f the externally applied pressure on the samples. For a constant external p ressure the observed decrease has a linear behavior as a function of time. The undoped lamellar silica, when pressed under 760 mPa for 45 min, exhibit ed a decrease of the interlamellar distance of 16%. The obtained results su ggested that under an increased external pressure, cadmium is forced to cha nge its coordination environment, to adjust to a most stable structure. (C) 2000 Elsevier Science B.V. All rights reserved.