カソード分極下におけるジルコニウム内部での水素と重水素の拡散

抄録

The diffusion behaviour of hydrogen and deuterium in Zr during cathodic discharge was studied by direct measurement of their concentrations. These were estimated by a volumetric measurement of the chemical dissolution of the metal hydride layer and a d-d fusion method of deuteron bombardment to the metal layer including deuterium. The diffusion behaviour was analysed with a simple push model that the diffusing hydrogen or deuterium atom interact directly with another hydrogen or deuterium atom composed hydride or deuteride. The activation energy of diffusion for hydrogen and deuterium in their hydride layer showed the same value of 49.0 kJ /mol and they were almost the same as in other papers. But the diffusion coefficients of hydrogen (D_DH) and deuterium (D_HD) showed a big difference; the ratio of D_DH⁄D_HD=14.4 is extremely large compared with another value of nearly 3 obtained using a conventional diffusion model. The reason for the big difference is considered as follows. The diffusion process can be divided into several stages of the fundamental process. They are the discharge of the hydrogen ion from the solution to metal surface adsorption, the dissolution to metal from the surface, the diffusion through the hydride layer and the combination with the metal atom. The ratio of D_DH⁄D_HD for this model has a value of less than 4. But in the case of the push model in which the hydrogen atoms interacts with each other, the ratio becomes 11.3.