Mechanically induced structural modifications in metal-doped lamellar silica

Lamellar silica samples were synthesized by a neutral amine process and structural modifications were induced by copper nitrate or sulfate addition. The lamellar silica showed three diffraction peaks at 2 theta values of 3.8, 7.3 and 11.5 degrees, due to the 001, 002 and 003 diffraction planes. Addition of copper nitrate or sulfate affected the structure of the starting matrices as demonstrated by X-ray diffraction patterns. Both metal-doped lamellar silicas were mechanically induced to react in the solid state with potassium bromide, to give products which exhibited significant structural modifications. The thermal stability of the lamellar silica samples increased by addition of copper salts. Thus, the precursor lamellar silica and the corresponding nitrate and sulfate metal-doped samples started to degrade at 105 degrees C, 130 degrees C and 230 degrees C, respectively. Structural and thermal measurements on these samples exhibited an increased resistance to decomposition, however, the nitrate and sulfate anions caused remarkable structural modifications in the synthesized matrices. (C) 2000 Elsevier Science B.V. All rights reserved.