Production of palladium-silver thin film alloys and measurements of phase diagrams of the palladium(1-x)silver(x)hydrogen system

PdAg Alloy thin films of different compositions were fabricated by crosscondensation of two atomic fluxes on temperature controlled quartz crystal substrates. The fluxes were generated by thermal evaporation of pure materials produced by two electron-beam-guns (e-guns). The process took place under clean high vacuum conditions. Film thickness, growth rate and composition were precisely computer-controlled utilizing three quartz crystal mass monitors (QCM) and a combination of shutters. Criteria for quality of the films were accuracy and homogeneity of thickness and alloy composition. Hydrogen pressure and temperature were carefully controlled for the performance of the hydrogen cycling process in order to study the interaction of hydrogen with the metal alloy thin film structures.; All process variables were automatically monitored and controlled to eliminate inaccuracies inherent in manual control. Software and hardware were developed for repeatability of the process parameters and variables to ensure reproduction of the evaporation and hydrogen-cycling processes.; Phase diagrams consisting of pressure concentration relations from repeated hydrogen cycling processes were measured using the QCM technique. Results on palladium hydride obtained using the volumetric technique were combined with results from the QCM on similar systems for the development of an empirical method to extract the stress effect inherent in the QCM produced by the expansion of the volume of the palladium host lattice upon hydrogen adsorption. As a consequence bulk behavior of the phase diagrams for thin films thicker than 2500 A were predicted.; The results describe the evolution of the phase diagrams of palladium thin films as their thicknesses approach bulk. The evolution of features of the phase diagrams as the incorporation of silver in the palladium host structure changes from 0 to 30% is also described. A reduction of the hydrogen solubility of the PdAg structure occurs as the silver composition increases. These results are in good agreement with bulk results done by others.