Coincidence Doppler broadening of the positron annihilation technique was employed to identify the defects in thermally annealed 'as-received' ZnO and thermally annealed ball-milled nanocrystalline ZnO. Results indicate that a significant amount of O vacancy was created in ZnO due to annealing at about 500C and above. The results also indicate that the Zn vacancy created during the ball milling process could be easily removed by annealing the sample at about 500C and above. The defect characterization had also been correlated with the magnetic properties of ZnO.

Defect Studies in Annealed ZnO by Positron Annihilation Spectroscopy. Sanyal, D., Roy, T.K., Chakrabarti, M., Dechoudhury, S., Bhowmick, D., Chakrabarti, A.: Journal of Physics - Condensed Matter, 2008, 20[4], 045217