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Science 8 February 2008:
Vol. 319. no. 5864, pp. 794 - 797
DOI: 10.1126/science.1151442
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Reports

Colossal Positive and Negative Thermal Expansion in the Framework Material Ag3[Co(CN)6]

Andrew L. Goodwin,1* Mark Calleja,2 Michael J. Conterio,1 Martin T. Dove,1 John S. O. Evans,3 David A. Keen,4,5 Lars Peters,3 Matthew G. Tucker4

We show that silver(I) hexacyanocobaltate(III), Ag3[Co(CN)6], exhibits positive and negative thermal expansion an order of magnitude greater than that seen in other crystalline materials. This framework material expands along one set of directions at a rate comparable to the most weakly bound solids known. By flexing like lattice fencing, the framework couples this to a contraction along a perpendicular direction. This gives negative thermal expansion that is 14 times larger than in ZrW2O8. Density functional theory calculations quantify both the low energy associated with this flexibility and the role of argentophilic (Ag+...Ag+) interactions. This study illustrates how the mechanical properties of a van der Waals solid might be engineered into a rigid, useable framework.

1 Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK.
2 Cambridge eScience Centre, Wilberforce Road, Cambridge CB3 0WA, UK.
3 Department of Chemistry, University Science Laboratories, University of Durham, South Road, Durham DH1 3LE, UK.
4 ISIS Facility, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX, UK.
5 Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.

* To whom correspondence should be addressed. E-mail: alg44{at}cam.ac.uk

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
eScience for molecular-scale simulations and the eMinerals project.
E.K.H Salje, E Artacho, K.F Austen, R.P Bruin, M Calleja, H.F Chappell, G.-T Chiang, M.T Dove, I Frame, A.L Goodwin, et al. (2009)
Phil Trans R Soc A 367, 967-985
   Abstract »    Full Text »    PDF »
Large negative linear compressibility of Ag3[Co(CN)6].
A. L. Goodwin, D. A. Keen, and M. G. Tucker (2008)
PNAS 105, 18708-18713
   Abstract »    Full Text »    PDF »


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