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 MgAl2O4 nanoparticles with sizes larger than 42 nm.