Annealing effects in ZnO and ZnO–SnO2 powders during grinding

We report on the differences in the defect structure of ZnO particles that take place at the grinding of powders of pure ZnO and mixture ZnO–SnO2. The defect structure formed was studied by electron paramagnetic resonance (EPR). The results demonstrate that a sequential two-stage thermal process contributes to the defect structure during prolonged mechanical treatment (MT). In the first stage of MT a collective process of break up of individual ZnO particles occurs and the defect structure is caused by hyper-rapid thermal defects annealing (HRTDA) of the particles. The second stage of the process of defect formation is associated with annealing effects caused by the sample heat accumulation.