title: Simulation study of negative thermal expansion in yttrium tungstate Y2W3O12.
abstract: A simulation study of negative thermal expansion in Y2W3O12 was carried out using calculations of phonon dispersion curves through the application of density functional perturbation theory. The mode eigenvectors were mapped onto flexibility models and results compared with calculations of the mode Grüneisen parameters. It was found that many lower-frequency phonons contribute to negative thermal expansion in Y2W3O12, all of which can be described in terms of rotations of effectively rigid WO4 tetrahedra and Y-O rods. The results are strikingly different from previous phonon studies of higher-symmetry materials that show negative thermal expansion.
authors.affiliation: School of Physics and Astronomy and Materials Research Institute, Queen Mary University of London, Mile End Road, London, E1 4NS, UK. CrystalMaker Software Ltd, Centre for Innovation & Enterprise, Oxford University Begbroke Science Park, Woodstock Road, Begbroke, Oxfordshire, OX5 1PF, UK. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK.
authors.forename: Leila H N
authors.initials: LH
authors.lastname: Rimmer
authors.forename: Martin T
authors.initials: MT
authors.lastname: Dove