A low-temperature X-ray diffraction study of Pd and some Pd-H alloys

The lattice parameter of Pd has been measured between room temperature and 6K and has been found to be a smooth function of temperature over this range. An investigation of the X-ray diffraction patterns of some beta phase Pd-H alloys and a mixed ( alpha + beta ) phase alloy and of their dependence on cooling through the 50K region, where anomalies in a number of physical properties of beta -phase Pd-H are known to occur, showed no discernible effect on the state of strain of the Pd lattice, i.e., no indication of homogeneous lattice strain in excess of 2.5*10 -5 , nor evidence of line broadening indicative of inhomogeneous strains. Some consequences of this result for mechanisms which have been suggested to account for these anomalies are considered.