AB INITIO STUDY OF THE INFLUENCE OF PRESSURE ON THE HYDROGEN DIFFUSION BEHAVIOR IN ZIRCONIUM HYDROGEN SOLID SOLUTION

We studied stress dependence of hydrogen diffusion behavior in zirconium by using density functional theory. Hydrogen solution energy was examined as a function of stress and we found that tensile stress leads to increase in hydrogen solution energy because it induces lattice expansion. Similarly, stress promotes increasing of partial molar volume of hydrogen and anisotropic stress along z direction has the largest impact on it. From the investigation of potential energy curves of hydrogen diffusion, we investigated activation energy and diffusion constant from T site to O site and O site to O site, respectively. The activation energy for hydrogen diffusion is decreased by stress, which induces lattice expansion perpendicular to. diffusion path. Diffusion constant is increased by stress, which increases diffusion path length.