Observation of Hydrogen Permeation into Molybdenum Disulfide Crystal

Abstract

Permeation of hydrogen into the molybdenum disulfide crystal (MoS₂) in the hydrogen atmosphere is investigated from a view point of gas release by cleavage. MoS₂ crystals are exposed to H₂ or D₂ gas at temperatures between RT and 600°C, followed by the cleavage at the same temperatures after evacuation of H₂ or D₂ gas. The dependence of amount of outgassing on the exposed temperature shows similar tendency in H₂ and D₂ except maximum outgassing temperature. The concentration of hydrogen in the bulk increases at the temperature of 400 or 500°C due to permeation from the surface to the bulk. Beyond the temperatures the concentration in the bulk decreases due to thermal desorption. Regardless of the exposure to D₂ gas, many D atoms are detected. The concentration of dissociated hydrogen atoms in MoS₂ depends on the exposure temperatures.