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-TaD 0.55 in the temperature range 6S-80 o C. The intensity distribution of 1/2 1/2 0 type diffuse pseudo-Bragg reflections is 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-VD 0.5 and α-NbH x =0.05-0.6. Warren-Cowley's short range order parameter and the short range displacement are calculated