The Debye-Waller factor due to static displacement around hydrogen in niobium

Abstract

Hydrogen dissolved in niobium in the high temperature α phase decreases the Bragg intensity by producing static displacements, which can be described by a static Debye-Waller factor (DWF), of the niobium atoms from their average lattice sites. The relative integrated intensity of Bragg reflections from single-crystal NbH c was measured. The corresponding static DWF decreased with the concentration ( c < 0.2 hydrogen atoms per niobium atom) and the order of the reflection, as predicted by theory. For small scattering vectors the static DWF is primarily determined by the displacements of the niobium atoms closest to the hydrogen impurity. Therefore the attenuation of the low order Bragg reflections was used to determine the displacements of these niobium atoms ( u 1 = 0.1 A ̊ ). The measurement of the static DWF appears to be a simple and useful method for the determination of displacements located near impurities and other lattice defects.