Temperature coefficient of resistivity at compositions approaching PdH

Measurements have been made of the temperature coefficient of resistivity, lambda, versus hydrogen concentration, H/Pd, at very high concentrations in the Pd-II system. Unusually high hydrogen compositions were achieved using an electrochemical loading procedure which allowed stable Pd-H systems to be obtained. It is well known that increasing the H/Pd concentrations leads to three different phases (alpha, alpha + beta, beta), respectively, in th e Pd-H system; the phase is thought to end in an asymptotic limit. Possible evidence that a new phase (gamma) exists, bordering the beta phase at comp ositions H/Pd > 0.9 is reported and discussed. (C) 2000 Elsevier Science B. V. All rights reserved.