The synthesis of a high value-added product, gahnite ferroan nano composite, from a mixture of fly ash silica and ZnO is a low-cost and non-expensive technique. The XRD pattern clearly reveals the synthesized product from fly ash after leaching is a product of high-purity gahnite ferroan composite. The grains are mostly cubical in shape. The optical band gap of powdered gahnite ferroan nano composite is 3.37 eV, which acts as a UV protector. However, the bulk sample shows that the 500 to 700 nm wavelength of visible light is absorbed, and UV light is allowed to pass through. So, the bulk sample acts as a band pass filter of UV light which can be used in many optical applications for conducting UV-irradiation activity. Dielectric permittivity and dielectric loss increase with a rise in temperature. The increase in the ac conductivity at higher temperatures denotes the negative temperature coefficient resistance (NTCR) behavior of the material.

A chemical reactor is designed and developed to synthesize silica nano-powders by oxidation of tetraethyl orthosilicate (TEOS) using a three-port diffusion flame burner. Nano-silica powders were successfully synthesized. The particle size of the silica powders were confirmed by AFM and TEM techniques. Scanning electron microscopy (SEM) reveals that as-synthesized silica powders are in agglomerated condition. Phase analysis using XRD shows that the nano-silica in as-prepared condition is in amorphous form. However, during subsequent heattreatment, it becomes crystalline.

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