Investigating the Diffusion Properties of Hydrogen in Zr–Ti Alloys by First-Principles Calculations

Zr/Ti-based alloys are high-quality hydrogen storage materials, which are formed by adding other transition metals or even rare earth metals into zirconium and titanium metals in a certain proportion, and have a wide application prospect. In order to find Zr–Ti alloy materials with excellent hydrogen absorption performance, the transport properties of H in Zr–Ti alloy were studied. The first-principles calculation is used to calculate the formation energy of H at different gaps in Zr7Ti29 alloy, and the gap stability of H is discussed. It found that H can stably exist in Zr7Ti29 and is more inclined to occupy the tetrahedral gap. Then, the microscopic diffusion mechanism is discussed, the diffusion energy barrier between the adjacent gaps of H in Zr7Ti29 is calculated, and the optimal diffusion paths are obtained by considering different diffusion sizes and paths. By comparing the diffusion barrier of H among the elemental Zr, elemental Ti, and Zr7Ti29, we found that H is more active in Zr7Ti29. Finally, the diffusion coefficient of H in Zr7Ti29 and Zr18Ti36 was calculated; the results show that the diffusion coefficient of H is larger in Zr7Ti29.