Concentration and temperature dependence of the electrical resistivity of quenched PdH_x

Abstract

The hydrogen concentration dependence of the electrical resistivity rho (x) of rapidly cooled PdHx samples is investigated at 4.2K and 77.4K for 0<or=x<or=0.015. The resistivity data show that the hydrogen atoms are homogeneously distributed in the host metal up to a concentration x approximately=0.005. In this regime drho /dx=25 mu Omega cm. This value is reproduced by a simple model where scattering between electron states on the Gamma sheet on the Fermi surface and between states on the Gamma sheet and the d band jungle-gym is taken into account. This model leads to a maximum in rho (x) at x=0.4 for temperatures above the critical temperature Tc=566K of the PdHx system. Below Tc (especially at 4.2K) the concentration dependence of rho is dominated by the segregation in the alpha and alpha ' phases for 0<or=x<or=0.65. In this concentration range the experimental data can be described by assuming a random distribution of dilute alpha phase spheres in the alpha ' phase PdHx matrix.