Abstract
The deuteron magnetic resonance of tantalum deuterides exhibits spectra of unexpectedly large asymmetry parameter, which suggests the existence of atomic displacement of tantalum. The asymmetry parameter is maximum at a stoichiometric composition of Ta2D, and decreases as x in Ta2D1+x increases. This suggests that the difference in the deuterium population between the 2a and 2d interstices, which is the origin of the atomic displacement of tantalum, becomes smaller. The relation between the atomic displacement, Δ, and the asymmetry parameter, η, is calculated by using a simple electrostatic model and under the condition that the deuterium atoms jump rapidly between the 2a and 2d positions. Comparison of the calculated and the observed concentration dependence of η shows that the β type hydride in which one deuterium exists in the 2za and x deuterium in the 2d, is stable at least up to x=0.6.
