Hydrogen redistribution in the solid solutions ZrV 2D x, 2.2≤ x≤2.7 : I. Interconnection between hydrogen-ordered phases: intermediate phase instead of phase separation

Abstract

We have studied, by means of neutron powder diffraction, the temperature evolution of the hydrogen solid solutions ZrV 2D x in the intermediate range, 2.18≤ x≤2.73, separating two hydrogen-ordered phases, ZrV 2D ≤2 with k =(1/2, 1/2, 1/2) and ZrV 2D ≥2.8 with k =(0, 0, 1− δ). Instead of ordinary phase separation, we have found an uncommon phase. This phase is a kind of a disordered one and, simultaneously, it keeps a modulation of hydrogen density with the same k as for the ordered phase, one or another. Under favourable conditions this modulation transforms into the regular ordered phase.