FIGURE 2 SEM planar image and EDS spectra of dark grey AlN powder sample: (a) SEM image; (b) and (c) EDS spectra of square areas 1 and 2 in Figure a, respectively
The surface morphology of the dark grey AlN powder sample is shown in Figure 2a. The AlN particles are mostly spherical, where a portion agglomerate to form big secondary particles. EDS tests show that the smooth particle contain only Al and N elements (Figure 2b), corresponding to pure AlN particles. In contrast, the rougher particles contain higher C and O contents, along with the Al and N elements (Figure 2c). In these samples, C and O impurities exist, due to the incomplete synthesis of AlN.
Mesophase