Strain Effects in the X-ray Determination of Lattice Parameters in Pd-H_x

Abstract

X-ray lattice parameter determinations for the β-phase in Pd-H_x have revealed a variation in a(x), the lattice parameter, that depends on the method of preparation. Samples loaded to a concentration of x > 0.6, by avoiding the mixed phase region, have a lattice parameter slightly lower than samples loaded to the same concentration by passing through the mixed phase region. The difference is thought to result from unrelieved strain produced as a result of the α → β phase change. These results point to a significant correction of the a(x) data of Schirber and Morosin¹, which have become widely used for determining hydrogen concentrations from lattice parameter measurements. A full account of these experiments is being published elsewhere.