Diffusivity and solubility of oxygen in solid palladium

Abstract

The solid solubility c(O) of oxygen in palladium in equilibrium with gaseous oxygen has been determined from absorption-desorption experiments for temperatures T of 1123 and 1173 K and oxygen partial pressures p(O2) between 2.7 x 10(3) and 4.0 x 10(4) Pa. The relationship between c(O), p(O2) and T is given by c(O) = a root p(O2) exp(-Delta H(s)/RT), where R = 8.314 JK(-1) mol(-1) is the universal gas constant, Delta H(s) = - 13.55 kJ/mol denotes the heat of solution of oxygen in palladium and the constant a amounts to 4.26 x 10(-5) at.%/root Pa or 6.41 x 10(-8) wt%/root Pa. The diffusion coefficient D(O) of oxygen in solid palladium has been determined by incomplete isothermal internal oxidation of Pd-Fe alloys using the data on the oxygen solubility in palladium. The temperature dependence of D(O) obeys the Arrhenius equation D(O) = D(0)exp(-E(d)/RT) with pre-exponential factor D(0) = 2.33 x 10(-7) m(2)/s and activation energy of diffusion of oxygen in palladium, E(d) = 102.76 kJ/mol