Critical behavior of hydrogen in Nb/Ta superlattices

Abstract

We present an in situ x-ray scattering study showing the existence of the lattice-gas lattice-liquid phase transition for H dissolved in Nb/Ta superlattices where it is found that critical fluctuations with wavelengths shorter than the superlattice periodicity are suppressed. Since fluctuations of only long wavelengths develop, phase separation into gas and liquid phases cannot occur. These results demonstrate that the coherent phase transition is sensitive to the microscopic properties of the H-H interaction.