Optical and Micro-Raman Characterization of Fused Mullite Prepared from Beach Sand Sillimanite

Abstract

Plasma-fused mullite compounds were prepared from beach sand sillimanite with varying sillimanite and alumina ratio (60:40 = MU1, 65:35 = MU2, and 75:25 = MU3) within five minutes of thermal plasma treatment. The X-ray diffraction (XRD) and micro-Raman studies indicate the presence of corundum phase in MU1 and MU2 compounds, whereas no signature of corundum phase is evident in MU3. This observation confirms that sillimanite and alumina taken in the ratio 75:25 (MU3) are exactly in the appropriate proportion for the complete conversion of mullite. The bulk density is higher in fused MU3 as compared to other two compositions. The optical band gap measured using UV-Visible spectrophotometer for this composition is found to be 3.37 eV.

Keywords:

• Mullite
• Optical
• Plasma melting
• Raman
• Refractory
• XRD

ACKNOWLEDGMENT

The authors are grateful to Director, IMMT (CSIR), Bhubaneswar, India, for providing research support.