Interstitial D sites in D-doped samples of the A-15 compound, Ti3IrDx, with x equal to 0.70 or 3.63 (Pm¯3n), were studied by using neutron diffraction techniques. In the case of x = 0.70, the D-occupation of 6-fold d-positions (6d positions) was confirmed; as in the case of other H- and D-doped A-15 compounds. Complete and unique occupation of these positions yielded an x-value of 3. Thus, it was found (for a sample with x = 3.63) that there was an additional occupation of 24k (or nearly 24k) positions. The results suggested the operation of a structural mechanism that successively replaced 6d positions with 2 adjacent and simultaneously occupied 24k positions in order to permit x-values of more than 3.

K.Cornell, H.Wipf, U.Stuhr, A.V.Skripov: Solid State Communications, 1997, 101[8], 569-73