Well-Defined Hexagonal Platy Particles of Brucite, Brucite/Silica Core Shell, and Hollow Silica Particle

Abstract

Abstract Well-defined Mg(OH)2 (brucite) hexagonal platy particles with the lateral size of 80 nm were prepared by precipitation from an aqueous solution of magnesium chloride using a flow reactor with controlled pressure injection. The brucite particles were coated with a thin silica layer by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) catalyzed by ammonium hydroxide to obtain Mg(OH)2@SiO2 core-shell nanoparticle. The heat treatment of the Mg(OH)2@SiO2 in air at 500 °C resulted in the transformation of brucite to periclase MgO. The Mg(OH)2 and MgO cores were removed from Mg(OH)2@SiO2 and MgO@SiO2 core-shell particles by etching with hydrochloric acid to obtain hollow silica particles with a lateral size range of 6 to 12 nm. Meanwhile, heat treatment of the Mg(OH)2@SiO2 at 1000 °C resulted in the transformation of brucite to periclase and forsterite.