Diffusivity and solubility of oxygen in solid palladium

The solid solubility cO 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 × 103 and 4.0 × 104 Pa. The relationship between cO, p_O₂ and T is given by cO = a√ p_O₂ exp ( - Hₛ /RT) , where R = 8.314 JK−1 mol−1 is the universal gas constant, ΔHs = −13.55 kJ/mol denotes the heat of solution of oxygen in palladium and the constant a amounts to 4.26 × 10- 5 \,at.% /√Pa or 6.41 × 10- 8 \,wt% /√Pa . The diffusion coefficient DO 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 DO obeys the Arrhenius equation DO = D 0 exp(−Ed/RT) with pre-exponential factor D 0 = 2.33 × 10−7 m2/s and activation energy of diffusion of oxygen in palladium, Ed = 102.76 kJ/mol