Solid-State Reaction Synthesis of MgAl₂O₄ Spinel from MgO-Al₂O₃ Composite Particles Prepared via Electrostatic Adsorption

This paper presents the formation of magnesium aluminate spinel using composite particles prepared via electrostatic adsorption (ESA). Scanning electron microscopy (SEM) images confirmed the presence of Al2O3-MgO composite particles. A mixture of Al2O3 and MgO raw materials was also prepared by using the conventional bead-milling method for comparison. The samples sintered at elevated temperatures were characterized through X-ray diffraction, SEM, and relative density measurements. Additionally, the lattice parameter and strain of the samples were determined using the Nelson-Riley function and the Williamson-Hall equation. A pure spinel phase formed in the ESA-derived sample sintered at 1400 degrees C, while the MgO structure remained in the conventionally prepared sample sintered at 1600 degrees C. The densities of samples sintered at 1450 degrees C or higher exceeded 90%. The lattice strain of the prepared samples was inversely proportional to the sintering temperature, attributed to the formation of large grains at higher temperatures. However, the sample sintered at 1600 degrees C for 8 h exhibited the highest strain of 0.0074 because the crystals grew in a certain direction.