Rietveld refinement of the A3B (D019) and A2B (B82) phases in Ti–Sn and Ti–Ga alloys

The structures of A3B (D019) and A2B (B82) phases have been investigated using Rietveld refinement of XRD data. The analyzed chemistry of individual phases has been used to determine the site occupancy of initial models. The shifts in Ti atoms corresponding to 6(h) Wyckoff positions have been calculated in both the Ti3Sn and Ti3Ga phases. This is related to the presence of symmetry elements in D019 structure which in turn allows local shift due to different site occupancies resulting in different potentials. The nature of atomic shift is opposite in Ti3Sn and Ti3Ga phases. The site occupancy patterns of A3B (Ti3Sn, Ti3Ga) and A2B (Ti2Sn and Ti2Ga) are different due to unlike chemical compositions.