A new solution route to silicates. Part 3: Aqueous sol-gel synthesis of willemite and potassium antimony silicate

Willemite, α-Zn2SiO4, and KSbOSiO4 (KSS) were prepared by an aqueous sol-gel process, starting from a H2Si2O5 solution as silicon source. Willemite was obtained free from impurities, in a teflon-lined bomb at 473 K under autogenous pressure. In the case of KSS, the same procedure results in a clear solution which gives, by evaporation at room temperature, an amorphous gel. Orthorhombic KSS crystallizes from this gel at 1273 K.