Growth of magnesium aluminate nanocrystallites

Nanocrystalline magnesium aluminate was synthesized with the coprecipitation method. Its growing behaviors as a function of temperature were studied with synchrotron X-ray diffraction (XRD) and Raman spectroscopy. It is found that the particle growth was greatly inhibited at temperatures below 1000°C due to the hydroxide precursor reactants. Above 1000°C, magnesium aluminate nanoparticles start to grow fast. After two hours annealing at 1200°C, the grain size changes by multiple folds, suggesting that oriented attachment may occur. Above 1200 °C, the grain size changes in various directions are much smaller than the average grain size, indicating the oriented attachment mechanisms become inactive in the growth of MgAl₂O ₄ nanoparticles with sizes larger than 42 nm.