Mechanically induced structural modifications in metal-doped lamellar silica

Lamellar silica samples were synthesized by a neutral amine process and str uctural modifications were induced by copper nitrate or sulfate addition. T he 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. Addi tion of copper nitrate or sulfate affected the structure of the starting ma trices as demonstrated by X-ray diffraction patterns. Both metal-doped lame llar silicas were mechanically induced to react in the solid state with pot assium bromide, to give products which exhibited significant structural mod ifications. The thermal stability of the lamellar silica samples increased by addition of copper salts. Thus, the precursor lamellar silica and the co rresponding nitrate and sulfate metal-doped samples started to degrade at 1 05 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 s tructural modifications in the synthesized matrices. (C) 2000 Elsevier Scie nce B.V. All rights reserved.