In situ measurement of elastic properties of PdHx, PdDx, and PdTx

The Young's modulus E of palladium hydride PdHx, deuteride PdDx and tritide PdTx were measured for studying the effect of both hydrogen stoichiometry x and isotope nature. A special technique based on optical detection of flexural modes of a palladium cylindrical microcantilever was adapted to in situ measurements to guarantee the sample homogeneity during the hydriding process. A 10% decrease in E was found between pure polycrystalline palladium and hydride phases. The non linear dependence observed with the H content was discussed in terms of lattice expansion, phonons and electronic properties. Sensitivity of the technique enables to distinguish an isotope effect on E