Synthesis of pure nanocrystalline magnesium silicate powder

Pure nanocrystalline forsterite (Mg₂SiO₄) powder was synthesized by mechanical activation technique followed by subsequent annealing. The starting materials were talc [Mg₃Si₄O ₁₀(OH)₂], magnesium carbonate (MgCO₃), and magnesium oxide (MgO) powders. To produce forsterite, two mixtures were prepared including talc and magnesium carbonate (first mixture) as well as talc and magnesium oxide powders (second mixture). First, both mixtures were milled by a planetary ball mill, and then annealed at 1000 and 1200°C for 1 h. Differential thermal analysis (DTA), X-ray diffraction (XRD), atomic absorption spectrometry (AAS), transition electron microscopy (TEM), and scanning electron microscopy (SEM) techniques were utilized to characterize the initial and synthesized powders. A pure nanocrystalline forsterite with a mean crystallite size of 40 nm was obtained after 10 h ball milling of the first mixture and subsequent annealing at 1000 °C for 1 h. On the contrary, after 5 h of mechanical activation of the second mixture and subsequent annealing at 1000°C for 1 h, pure nanocrystalline forsterite was synthesized with 60 nm mean crystallite size.