Influence of biaxial strain on thermodynamical properties of hydrogen in (001) oriented Mo/V superlattices

The influence of the strain state on the thermodynamics of hydrogen in quasi-two-dimensional V layers embedded in three Mo/V superlattices is reported in the temperature range 140-300°C. The enthalpy change in the two lower strained V layers was found to be low in the low concentration range and approached the disordered V bulk value through an attractive hydrogen-hydrogen (H-H) interaction. For the most strained V layer the enthalpy change was larger in the low concentration range and decreased with a repulsive H-H interaction. The entropy change for the hydrogen in the V layers in the three superlattices was found to be much higher than that for V bulk and approached the bulk β-phase value. This indicates a less energetically favourable interstitial site for the hydrogen to occupy. © 2003 Elsevier B.V. All rights reserved.