Synthesis of nano magnesium oxide: a study on a magnesium sulfate-ammonium citrate chelation system

To efficiently utilize low-cost magnesium sulfate heptahydrate resources by developing MgO ceramics with superior properties, a novel synthesis route was proposed, involving the preparation of [Mg(NH₃)₃]²⁺ complexes through the reaction of magnesium sulfate heptahydrate with ammonium citrate, followed by calcination to obtain MgO nanoparticles. These nanoparticles were subsequently sintered to fabricate MgO ceramics. The impact of calcination temperature on the phase structure, chemical composition, and morphology of MgO nanoparticles was systematically investigated, and the mechanical properties of the resulting ceramics were comprehensively evaluated. In this study, magnesium sulfate was used as the raw material and ammonium citrate as the chelating agent, and the complex was generated at 120 °C. After calcination at 1000 °C, high-purity MgO nanoparticles with a regular shape, an average particle size of 109 nm, and a lattice spacing of 0.39 nm were successfully obtained. After sintering, the MgO ceramics exhibited a bulk density of 3.41 g cm⁻³, demonstrating the feasibility and potential of this new approach for producing high-quality MgO ceramics from abundant magnesium sulfate heptahydrate resources.