title: Resolving the structure of TiBe12.
abstract: There has been considerable controversy regarding the structure of TiBe12, which is variously reported as hexagonal and tetragonal. Lattice dynamics simulations based on density functional theory (DFT) show the tetragonal phase space group I4/mmm to be more stable over all temperatures, while the hexagonal phase exhibits an imaginary phonon mode, which, if followed, would lead to the cell adopting the tetragonal structure. We then report the predicted ground state elastic constants and temperature dependence of the bulk modulus and thermal expansion for the tetragonal phase.
authors.affiliation: Centre for Nuclear Engineering, Department of Materials, Imperial College, London SW7 2AZ, England.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Jackson
authors.affiliation: School of EEandT, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Burr
authors.affiliation: Centre for Nuclear Engineering, Department of Materials, Imperial College, London SW7 2AZ, England.
authors.forename: Robin W
authors.initials: RW
authors.lastname: Grimes
keywords: beryllide; density functional theory; lattice dynamics; quasi-harmonic; thermal expansion