shows the FT-IR spectrum of precipitated SiO2. The IR band at 3437 cm-1 is due to the stretching vibration of H2O molecules. Correspondingly, the IR band at 1632 cm-1 is due to the bending vibration of H2O molecules. The shoulder at 3246 cm-1 could be assigned to the stretching vibrations of Si-OH groups in the structure of amorphous SiO2. The presence of the Si-OH group is proved as bonded water. The very strong and broad IR band at 1111 cm-1 with a shoulder at 1188 cm-1 is usually assigned to the TO and LO modes of the Si-O-Si asymmetric stretching vibrations. The IR band at 956 cm-1 can be assigned to silanol groups. In the case of alkali silicate glasses, this band is assigned to Si-O- stretching vibrations. The IR band at 800 cm-1 can be assigned to Si-O-Si symmetric stretching vibrations, whereas the IR band at 474 cm-1 is due to O-Si-O bending vibrations. Murphy and Greytak (1979) assigned the IR band at 380 cm-1 to the Si-OH wagging mode. In the present work, the IR band at 380 to 377 cm-1 is recorded as a shoulder at 378 cm-1.