Surface Topography and Deuterium Retention of Polycrystalline Tungsten and Nanocrystalline Tungsten Film Exposed to Deuterium Plasma

In this work, polycrystalline tungsten prepared by powder sintering and naonocrystalline tungsten film deposited by magnetron sputtering were simultaneously exposed to deuterium plasma with energy of 78 eV and fluence of 3.9 × 10²⁴ m⁻² at 450 K. The morphologies of both samples before and after deuterium plasma exposure were measured by scanning electron microscopy. Then, the deuterium retention of both samples was determined by thermal desorption spectroscopy. After irradiation, a few blisters were observed on polycrystalline tungsten, but no sign of surface modification was detected on nanocrystalline tungsten film. In addition, the deuterium retention is higher in nanocrystalline tungsten film than in polycrystalline tungsten. The fact that nanocrystalline tungsten film deposited by magnetron sputtering has a larger density of grain boundaries and native defects are responsible for no blistering and high retention in comparison with the polycrystalline tungsten.