Low temperature synthesis of forsterite from hydromagnesite and fumed silica mixture

Forsterite was prepared via solid-state reaction by using hydromagnesite (basic magnesia carbonate) and fumed silica, aiming at completing the reaction 2MgO+SiO2→Mg2SiO4 at low calcination temperature. The phase development and morphology evolution of the hydromagnesite and hydromagnesite–fumed silica mixture during heat treatment were characterized by means of scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) nitrogen-gas adsorption method, and X-ray powder diffraction (XRD). A diffusion distance of less than 300 nm for Mg2+ and Si4+ for forsterite formation was obtained because the formed high reactivity MgO with the nanosheet structure of its parental hydromagnesite and the fumed silica with particle size of less than 100 nm were homogeneously mixed. Monolithic forsterite was synthesized after calcination of the hydromagnesite–fumed silica mixture at 1100 °C.