X-Ray Measurement of the Coupling between Static and Thermal Displacements around Hydrogen in Niobium

Abstract

The authors report x-ray measurements of the attenuation of integrated Bragg intensities which is attributed to the static Debye-Waller factor, $\mathrm{exp}(\ensuremath{-}2L)$, due to hydrogen in Nb single crystals in the homogeneous $\ensuremath{\alpha}$ phase. For small hydrogen concentrations, the dependence of $2L$ versus the scattering vector, $\stackrel{\ensuremath{\rightarrow}}{\mathrm{K}}$, can be explained by the nonlinear coupling between static and thermal displacements around point defects. Detailed information about both types of displacements of the Nb atoms nearest to the interstitial hydrogen atom has been obtained.