Mechanically activated synthesis of single crystalline MgO nanostructures

One-dimensional (1D) MgO structures were successfully synthesized via carbothermic reduction of mechanically activated mixture of MgO and graphite. Mechanical activation of source materials before carbothermic reduction can substantially enhance the formation of MgO products at a temperature (1000 °C) relatively lower than that required in previous approaches (≥1200 °C). However, the morphology of MgO formed is dependent on the degree of mechanical activation and the condition of the subsequent carbothermic reduction. Two distinctive morphologies were found for MgO products synthesized using our method: single crystalline nanorods with rectangular cross-sections whose diameters range from 50 to 100 nm, and microfibers (∼5 μm in diameter) with and without branching. The synthesized products were systematically studied by XRD, SEM, TEM, and EDS. The results show that the nucleation and growth process of these morphologies seem to be a vapor–solid mechanism.

Research highlights▶ The effect of source material on the morphology of products (MgO nanostructures) was studied for the first time in this area of research. ▶ We investigate effects of the degree of mechanical activation during carbothermic reduction on the nature of the MgO products. ▶ Two distinctive morphologies were found for MgO products synthesized using our method: single crystalline nanorods with rectangular cross-sections whose diameters range from 50 to 100 nm, and microfibers (∼5 μm in diameter) with and without branching. ▶ We successfully synthesized MgO products at a temperature (1000 °C) relatively lower than that required in previous approaches (≥1200 °C). ▶ A mechanism based on the vapor–solid growth process is proposed for the formation of these morphologies.