Crystal structures of the Al-Ti-Pt τ 5 and τ 6 phases solved by zonal precession electron diffraction Academic Article uri icon


  • Abstract The earlier reported Al–Ti–Pt phases τ 5 and τ 6 were studied using Precession Electron Diffraction (PED) and Convergent Beam Electron Diffraction (CBED). Their atomic models were proposed applying Direct Methods to the PED zonal data. The τ 5-phase (FeCr- type, P4 2/mnm, a= 9.702 and c= 5.023 Å) can be described by the formula Al 2 Ti 5 Pt 3, positioning 18 Ti, eight Pt and four Al atoms at five unique atomic positions in the unit cell. The τ 6-phase (P2 1 3, a= 6.8477 Å) can be described by the formula Al 3 Ti 5 Pt 2. Its unit cell consists of 20 atoms at 12b and two 4a atomic positions occupied by Ti, Pt and Al atoms, respectively. Due to deviation from the stoichiometry, the τ 6-phase can be related to a defect variant of the Au 4 Al-type structure. The structures of the studied phases are presented as the stacking of coordination polyhedra.

publication date

  • February 5, 2015