Hydrogen is found to diffuse into and increase the conductivity of single ZnO crystals. The diffusion rates have been obtained, as well as the temperature and pressure dependencies of the quantity of hydrogen in the crystal. This quantity is found to be influenced by the electrons already in the crystal. It is thought likely that hydroxyl groups are formed from the hydrogen and oxide ions. The donor center has an ionization energy of 0.04 ev.

Experimental values for the solubility of carbon in nickel in the range 700°C to 1300°C yield the equation lnS=2.480−4,880/T, where S is the solubility in grams of carbon per 100 grams of nickel. Values obtained for the diffusion coefficient in the same range fit the equation lnD=0.909−20,200/T, where D is in cm2 per second. These results are of some interest in the problem of the activation of thermionic oxide coated cathodes, and the experimental method used to measure the diffusion coefficients is related to phenomena occurring in vacuum tubes. To extend the usefulness of the results in this direction, rates of reaction between diffused carbon and barium oxide coatings on nickel have been measured. It was found that the rates are diffusion limited over a wide range of conditions of interest.

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Low voltage electron diffraction and pumping speed measurements have been used to study the reactions of oxygen with clean Si (111) and (100) surfaces in the temperature range between 600° and 1000°C and the oxygen pressure range between 7×10−9 and 1×10−4 mm Hg. The results support the contention that a wide region in which Si is atomically clean exists in this range. Measurements of steady states yield an activation energy of about 90 kcal/mol for the clean-up process. The results also suggest a practical method for producing pure coatings of SiO2 by a technique similar to, but with several advantages over, the familiar Si+SiO2 reaction process.

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