Fig. 10 shows the SEM micrographs of the gained a-Al2O3
powders from precursors with different amounts of a-Al2O3 seed.
From the XRD analysis, we know that the pure a-Al2O3 can be
obtained from Al-3 until the calcination temperature reached to
1100 C. However, the pure a-Al2O3 from Al-7, Al-8 can be gained at
1000 C. The a-Al2O3 from Al-3 (Fig. 10a) has relatively larger
grains with seriously hard aggregation than the a-Al2O3 powders
with various amount of additives (Fig. 10b–d). Fig. 11 shows the
TEM micrographs of a-Al2O3 from different precursors. The Al2O3
from Al-3 had two kinds of particle size, which was caused by