Methods of introducing interstitial zinc into single crystals of zinc oxide were described which involve heating the crystals in zinc vapor followed by rapid quenching. The interstitial zinc atoms acted as donors with a low ionization energy and they were detected by the extra conductivity which they imparted to the crystals. At 180 to 350C, the diffusion coefficient of the donor obeyed:

Di = 5.3 x 10-4exp[-0.55(eV)/kT]

From these results the parabolic rate constant for the oxidation of metallic zinc may be calculated and the results were in good agreement with previous observations. The results of the high temperature diffusion of radioactive zinc into zinc oxide were less easy to understand and it may be that interstitial zinc was not involved in this process. Evidence was advanced that the defects were interstitial zinc atoms and not oxygen vacancies. The donors normally present in zinc oxide were not interstitial zinc atoms, but may be chemical impurities

Interstitial Zinc in Zinc Oxide. Thomas, D.G.: Journal of Physics and Chemistry of Solids, 1957, 3[3-4], 229-37