Influence of sintering temperature and pH on the phase transformation, particle size and anti-reflective properties of RHA nano silica powders

Nano silica powders were synthesized from rice husk ash, the most silica-rich raw material, using alkaline extraction followed by acid precipitation. The phase transformation during sintering, the influence of sintering temperature and pH on the particle size and anti-reflective properties of nano silica were investigated. The results showed that the amorphous SiO2 sintered at 600 degrees C were transformed to a cristobalite structures completely during the sintering process at 800 degrees C and 1100 degrees C. With the increasing sintering temperature and pH, the particle size distributions (d(50)) were increased respectively in the range of 62-84, 192-240, and 283-329nm at sintering temperatures of 600 degrees C, 800 degrees C, and 1100 degrees C. When the sintering temperatures were increased at 1100 degrees C, 98.15% and 96.84% of transmittances were obtained respectively at the highest and lowest points of the anti-reflection band and could be used for anti-reflective applications.