Thermal desorption of hydrogen in damaged materials and its implication for defect characterization

Abstract

Defects are ubiquitous in materials and their characterization is essential to materials development and deployment, but an immensely challenging task. Here, we advocate that thermal desorption spectroscopy (TDS) of hydrogen (H) can be used as a microscope to probe irradiation defect configurations in nuclear materials. Although TDS is widely used to measure the desorption of H in damaged materials during isochronal annealing, its utility to characterize defect configurations is rather limited. In this work, taking H retention and desorption in pre-damaged tungsten (W) as an example, we demonstrate the potential of TDS to probe vacancies in W by means of first-principles based multiscale modeling. We show that TDS of H, combined with multiscale modeling, can provide information on vacancy size, concentration and distribution in pre-damaged W, with simulated TDS results closely consenting to experimental observations. In addition, we clarify the key factors in affecting the peak temperature of TDS and reveal that the de-trapping attempt frequency of H from the vacancy cluster and vacancy clustering during annealing could have a profound effect on H desorption, which has been always neglected previously. The present study highlights the importance of TDS of H towards a quantitative assessment of vacancies in damaged materials.