Short-range-ordering of deuterium in α-TaD0.55

Elastic neutron scattering technique has been employed to study the short-range-ordering of deuterium atoms in α-TaD0.55 in the temperature range 65-80degC. The intensity distribution of 1/2 1/2 0 type diffuse pseudo-Bragg reflections in observed. Intensities of the 1/2 1/2 0 type diffuse reflection are not much temperature dependent as in the case of those observed in α-VD0.5 and α-NbHx = 0.05 - 0.6. Warren-Cowely's short range order parameter and the short range displacement are calculated. The existence of almost spherical microdomains having a β2-TaD0.5 type structure with a diameter of about 1.2 nm is concluded from the present neutron diffraction work. (author)