The Hydrogen Diffusion Rate Discontinuities of Palladium

Citation

Hassler, Gerald L. (1933) The Hydrogen Diffusion Rate Discontinuities of Palladium. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/fada-y381. https://resolver.caltech.edu/CaltechTHESIS:10082024-221240517

Abstract

The structure of sensitive properties of palladium metal are found to change discontinuously in such a way that the hydrogen concentration and the rate or hydrogen diffusion alter suddenly at a reproducible geometric series or hydrogen pressures. The data of two low pressure concentration studies and a number of low pressure diffusion rate studies are tabulated and plotted so as to show the discontinuities. The best set of values for the critical pressure, obtained by plotting a curve of "breaks", is: 2.6, 5,3, 10.6, 21.3, 42.5, 85, 170, 340, and 620 microns of mercury. A collection or absorption and diffusion rate data from the literature suggests an extension of this series to complete hydrogen saturation (Pd₄ H₂) at 350 millimeters of mercury.

A tentative statistical theory is proposed of the penetration or ionised atoms Into a crystal which has an intrinsic secondary structure. The theory predicts the concentration isotherm in terms of the transmission discontinuities. It describes a secondary structure which has finer spacing tor each successive higher concentration step and enables a calculation or the value of each spacing.

Several microphotographs or the palladium surface are shown. Measurements of the photographs are compared with the spacings predicted by the theory.

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