ANSTO Publications Online >
Journal Publications >
Journal Articles >

Please use this identifier to cite or link to this item: http://apo.ansto.gov.au/dspace/handle/10238/4520

Title: Scrutinizing negative thermal expansion in MOF-5 by scattering techniques and ab initio calculations
Authors: Lock, N
Christensen, M
Wu, Y
Peterson, VK
Thomsen, MK
Piltz, RO
Ramirez-Cuesta, AJ
McIntyre, GJ
Noren, K
Kutteh, R
Kepert, CJ
Kearley, GJ
Iversen, BB
Keywords: SCATTERING
THERMAL EXPANSION
METALS
VALENCE
ADSORPTION
NEUTRONS
Issue Date: 14-Sep-2012
Publisher: Royal Society of Chemistry
Citation: Lock, N., Christensen, M., Wu, Y., Peterson, V.K., Thomsen, M.K., Piltz, R.O., Ramirez-Cuesta, A.J., McIntyre, G.J., Noren, K., Kutteh, R., Kepert, C.J., Kearley, G.J., Iversen, B.B. (2012). Dalton Transactions, 42(6), 1996-2007.
Abstract: Complementary experimental techniques and ab initio calculations were used to determine the origin and nature of negative thermal expansion (NTE) in the archetype metal-organic framework MOF-5 (Zn4O(1,4-benzenedicarboxylate)3). The organic linker was probed by inelastic neutron scattering under vacuum and at a gas pressure of 175 bar to distinguish between the pressure and temperature responses of the framework motions, and the local structure of the metal centers was studied by X-ray absorption spectroscopy. Multi-temperature powder- and single-crystal X-ray and neutron diffraction was used to characterize the polymeric nature of the sample and to quantify NTE over the large temperature range 4-400 K. Ab initio calculations complement the experimental data with detailed information on vibrational motions in the framework and their correlations. A uniform and comprehensive picture of NTE in MOF-5 has been drawn, and we provide direct evidence that the main contributor to NTE is translational transverse motion of the aromatic ring, which can be dampened by applying a gas pressure to the sample. The linker motion is highly correlated rather than local in nature. The relative energies of different framework vibrations populated in MOF-5 are suggested by analysis of neutron diffraction data. We note that the lowest-energy motion is a librational motion of the aromatic ring which does not contribute to NTE. The libration is followed by transverse motion of the linker and the carboxylate group. These motions result in unit-cell contraction with increasing temperature. © 2012, Royal Society of Chemistry
URI: http://dx.doi.org/10.1039/C2DT31491F
http://apo.ansto.gov.au/dspace/handle/10238/4520
ISSN: 1477-9226
Appears in Collections:Journal Articles

Files in This Item:

There are no files associated with this item.

Items in APO are protected by copyright, with all rights reserved, unless otherwise indicated.

 

Valid XHTML 1.0! DSpace Software Copyright © 2002-2010  Duraspace - Feedback