Mg-doped Zn spheres, the higher growth temperature can produce
a larger diameter of the Mg-doped Zn spheres. Secondly, the
Mg-doped Zn spheres experienced an oxidation and the Mg-doped
ZnO product was formed on the quartz substrate after introducing
gas into the furnace. For the small diameter of Mg-doped Zn
spheres at 750 C, the inside and outside experienced an oxidation
at one time, resulting in the Mg-doped ZnO nanoparticles on the
quartz substrate after introducing gas into the furnace, as shown
in Fig. 2(a). With the increase of the diameter, the outside layer
of the Mg-doped Zn spheres was firstly oxidized after introducing
air into the furnace. The inner Mg-doped Zn spheres was further
vaporized and deposited on and in the existing Mg-doped ZnO
layers. In this step, the substrate temperature is the key point to