Density-functional theory calculation of hydrogen solubility in cubic silicon carbide at finite temperatures

Abstract

An ab initio framework using density-functional theory has been developed to predict hydrogen solubility in both pristine and defective \b{eta}-SiC. This study is motivated by the critical need for accurate hydrogen permeation models in fusion reactor designs, where predicting hydrogen permeation through tritium permeation barrier (TPB) materials is essential. Although silicon carbide is one of the leading candidates for TPBs, experimental permeation values vary widely due to differences between ideal single crystals and real, defect-containing materials. First principles calculations are employed to quantify the effects of interstitials, vacancies, and nonstoichiometric (amorphous) structures on hydrogen behavior in \b{eta}-SiC. Our results show that hydrogen solubility is significantly enhanced in carbon-rich nonstoichiometric amorphous structures and silicon vacancies compared to hydrogen occupying interstitial sites in pure \b{eta}-SiC.