The structure of the λ‐phase of niobium‐deuterium

Lambda phases of NbDx (0.78?x?0.84), which exist below 220 K, have been studied by neutron and electron diffraction. The observed modulated structure can be described as a deuteron concentration wave in a slightly distorted bcc Nb matrix. The wave‐vector is parallel to <001≳, and the wavelength varies from 16.0 A to 21.4 A, increasing with increasing concentration.