Novel rattling of K atoms in aluminium-doped defect pyrochlore tungstate

Simple item page
dc.contributor.authorShoko, Een_AU
dc.contributor.authorKearley, GJen_AU
dc.contributor.authorPeterson, VKen_AU
dc.contributor.authorMutka, Hen_AU
dc.contributor.authorKoza, MMen_AU
dc.contributor.authorYamaura, Jen_AU
dc.contributor.authorHiroi, Zen_AU
dc.contributor.authorThorogood, GJen_AU
dc.date.accessioned2016-10-26T03:39:45Zen_AU
dc.date.available2016-10-26T03:39:45Zen_AU
dc.date.issued2014-07-04en_AU
dc.date.statistics2016-10-26en_AU
dc.description.abstractRattling dynamics have been identified as fundamental to superconductivity in defect pyrochlore osmates and aluminium vanadium intermetallics, as well as low thermal conductivity in clathrates and filled skutterudites. Combining inelastic neutron scattering (INS) measurements and ab initio molecular dynamics (MD) simulations, we use a new approach to investigate rattling in the Al-doped defect pyrochlore tungstates: AAl0.33W1.67O6 (A = K, Rb, Cs). We find that although all the alkali metals rattle, the rattling of the K atoms is unique, not only among the tungstates but also among the analogous defect osmates, KOs2O6 and RbOs2O6. Detailed analysis of the MD trajectories reveals that two unique features set the K dynamics apart from the rest, namely, (1) quasi one-dimensional local diffusion within a cage, and (2) vibration at a range of frequencies. The local diffusion is driven by strongly anharmonic local potentials around the K atoms exhibiting a double-well structure in the direction of maximum displacement, which is also the direction of local diffusion. On the other hand, vibration at a range of frequencies is a consequence of the strong anisotropy in the local potentials around the K atoms as revealed by directional magnitude spectra. We present evidence to show that it is the smaller size rather than the smaller mass of the K rattler which leads to the unusual dynamics. Finally, we suggest that the occurrence of local diffusion and vibration at a range of frequencies in the dynamics of a single rattler, as found here for the K atoms, may open new possibilities for phonon engineering in thermoelectric materials. © 2014, IOP Publishing Ltd.en_AU
dc.identifier.citationShoko, E., Kearley, G. J., Peterson, V. K., Mutka, H., Koza, M. M., Yamaura, J., Hiooi, Z., & Thorogood, G. J. (2014). Novel rattling of K atoms in aluminium-doped defect pyrochlore tungstate. Journal of Physics: Condensed Matter, 26(30), 5401-5401. doi:10.1088/0953-8984/26/30/305401en_AU
dc.identifier.govdoc7442en_AU
dc.identifier.issn1361-648Xen_AU
dc.identifier.issue30en_AU
dc.identifier.journaltitleJournal of Physics: Condensed Matteren_AU
dc.identifier.pagination5401en_AU
dc.identifier.urihttp://dx.doi.org/10.1088/0953-8984/26/30/305401en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/7906en_AU
dc.identifier.volume26en_AU
dc.language.isoenen_AU
dc.publisherIOP Scienceen_AU
dc.subjectPyrochloreen_AU
dc.subjectAluminiumen_AU
dc.subjectSuperconductivityen_AU
dc.subjectAtomsen_AU
dc.subjectPhononsen_AU
dc.subjectThermoelectric materialsen_AU
dc.titleNovel rattling of K atoms in aluminium-doped defect pyrochlore tungstateen_AU
dc.typeJournal Articleen_AU
Files
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Journal Articles