The nanosized particles with an average size of 10–30 nm could
be seen more clearly using transmission electronic microscopy
(Fig. 3a). The EDS corresponding to the black particles (see Fig.
3a) is given in Fig. 3b. It can be seen that only two elements are
found: lead and aluminum (as shown in Fig. 3b). Based on Al–Pb
binary phase diagram, there is no intermetallic compound between
Al and Pb, indicating the particles shown in Fig. 2a and Fig. 3a are
lead phase which is a reaction product between BPOp and Al.The
existence and particle size of Pb phase are in good agreement with
XRD results. Furthermore, the gray region near certain lead particles
was analysed using selected area electron diffraction (SAED)
methods. The diffraction ring (shown in the inset of Fig. 3a) conforms
to Ba3Al2O6 compound (marked by the arrow in Fig. 3a).
However, there is no peak of Ba3Al2O6 compound in the XRD pattern.
It might be due to little volume fraction as well as lower scattering
factor of the compound.