Vibration spectroscopy on transformation of amorphous silica to α-cristobalite

By calcinating commercial silica at 1500 degrees C or adding sodium oxalate and calcinating at 850 degrees C, alpha-cristobalite was obtained. The Raman and IR spectra of amorphous silica and alpha-cristobalite were studied. The Raman and IR spectra showed obvious changes. While amorphous silica transformed to alpha-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 alpha-cristobalite, a strong new peak appeared at 620 cm(-1), and the adsorption at 800 cm(-1) increased considerably. alpha-cristobalite also has two adsorption peaks in far-infrared.