Spectroscopic characterization of sol-gel silica obtained by electron irradiation

In the present work, the gelation of tetraethoxysilane (TEOS) was carried o ut using electron irradiation. The electron source used was a 2 MeV Van de Graaff electron accelerator. Two samples were gelled; for the first one (Si O2-1), a solution of TEOS was irradiated with a total dose of 324 kGy. Afte rwards, NH4OH was added, and the gelation occurred instantaneously. The sec ond sample (SiO2-2), was prepared using a solution of TEOS, but in this cas e the ammonium hydroxide was added to the solution before irradiation. FTIR spectroscopy results show a significant energy band shift for the pre-hydr oxylized TEOS irradiated sample. The presence of room temperature stable OH - species was also established by EPR techniques in the SiO2-2 irradiated s ample. An unusually high acidity was observed in both samples. (C) 1999 Els evier Science B.V. All rights reserved.