Abstract:

 By calculating commercial silica at 1500℃ or adding sodium oxalate and calcinating at 850℃, α-cristobalite was obtained. The Raman and IR spectra of amorphous silica and α-cristobalite were studied. The Raman and IR spectra showed obvious changes. While amorphous silica transformed to α-cristobalite. The peak positions and peak shape changed, and new vibration mode appeared in the crystal phase. For amorphous silica, the Raman spectrum has a broad band between 210-515 cm- 1 and two weak peaks at 793 and 966 cm -1. After phase transition, the broad band split into two strong peaks at 416 and 231 cm-1, and the positions of weak peaks changed. The IR spectrum of SiO2 has two strong peaks at about 1100 and 480 cm-1 and a weak peak at 800 cm-1. For α-cristobalite, a strong new peak appeared at 620 cm-1, and the adsorption at 800 cm-1 increased considerably. α-cristobalite also has two adsorption peaks in far-infrared.

Key words: Amorphous silica, α-cristobalite, IR and Raman spectroscopy