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Local structure in Ag3[Co(CN)6]: colossal thermal expansion, rigid unit modes and argentophilic interactions

Conterio, Michael J.; Goodwin, Andrew L.; Tucker, Matthew G.; Keen, David A.; Dove, Martin T.; Peters, Lars; Evans, John S.O.

Authors

Michael J. Conterio

Andrew L. Goodwin

Matthew G. Tucker

David A. Keen

Martin T. Dove

Lars Peters



Abstract

Local structure in the colossal thermal expansion material Ag3[Co(CN)6] is studied here using a combination of neutron total scattering and reverse Monte Carlo (RMC) analysis. We show that the large thermal variations in cell dimensions occur with minimal distortion of the [Co(CN)6 ] coordination polyhedra, but involve significant flexing of the Co–CN–Ag–NC–Co linkages. We find real-space evidence in our RMC configurations for the importance of low-energy rigid unit modes (RUMs), particularly at temperatures below 150 K. Using a reciprocal-space analysis we present the phonon density of states at 300 K and show that the lowest-frequency region is dominated by RUMs and related modes. We also show that thermal variation in the energies of Ag...Ag interactions is evident in both the Ag partial pair distribution function and in the Ag partial phonon density of states. These findings are discussed in relation to the thermodynamic properties of the material.

Citation

Conterio, M. J., Goodwin, A. L., Tucker, M. G., Keen, D. A., Dove, M. T., Peters, L., & Evans, J. S. (2008). Local structure in Ag3[Co(CN)6]: colossal thermal expansion, rigid unit modes and argentophilic interactions. Journal of Physics: Condensed Matter, 20(25), Article 255225. https://doi.org/10.1088/0953-8984/20/25/255225

Journal Article Type Article
Online Publication Date May 22, 2008
Publication Date 2008-06
Deposit Date May 6, 2013
Journal Journal of Physics: Condensed Matter
Print ISSN 0953-8984
Electronic ISSN 1361-648X
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 20
Issue 25
Article Number 255225
DOI https://doi.org/10.1088/0953-8984/20/25/255225