ABSORPTION DESORPTION OF DEUTERIUM AT PD95-PERCENT-RH5-PERCENT ALLOY .1. ENVIRONMENT AND TEMPERATURE EFFECTS

The gas phase and electrolytic loading of Pd95%-Rh5% alloy with deuter ium were investigated. Gas loading was carried out isochorically under 900 mbar D-2, by decreasing the temperature from 900 degrees C to 20 degrees C. Although some D-2 was absorbed from high temperatures downw ards, most of the absorption was measured at 20 degrees C, at which th e [D]/[Me] (deuterium to metal atom) ratio exceeded the value typical for pure Pd. When the alloy deuterides were heated from 20 degrees C t o 900 degrees C, they where found to decompose for temperatures below 100 degrees C, but some deuterium was still absorbed at high temperatu res. The electrolytic insertion of deuterium was carried out potentios tatically in alkaline D2O electrolytes, the amount of deuterium loaded being determined by anodic extraction afterwards. The maximum [D]/[Me ] ratios thus achieved at 25 degrees C, which exceeded those obtained by gas loading, were found to increase with the alkalinity of the elec trolyte. With electrolytic insertion at 90 degrees C, alloy deuterides of large [D]/[Me] ratio could be obtained which, in the electrolytic environment, showed a thermal decomposition rate much slower than that tested in gas phase desorption experiments.