The diffusion of H at pressures down to 10-8torr was investigated by using mass spectroscopy. At pressures of 0.6 to 380torr, and temperatures ranging from 200 to 400C, the diffusivity was described by:

D (cm2/s) = 5.7 x 10-3 exp[-5.7(kcal/g-atom)/RT]

At pressures of 5 x 10-2 to 3 x 10-4torr, the permeability could be expressed by:

P (cm2/s torr½) = 1.80 x 10-3 exp[-3.745(kcal/g-atom)/RT]

J.A.Balovnev: Zhurnal Fizika Khimii, 1974, 48[3], 719-20

Figure 30

Diffusivity of H in Pd

(a: 50%CO2, b: 10%CO, c: 50%CO)