Negative X-ray expansion in cadmium cyanide
Open Access
- 12 February 2021
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Mater. Horiz.
- Vol. 8 (5), 1446-1453
- https://doi.org/10.1039/d0mh01989e
Abstract
Cadmium cyanide, Cd(CN)2, is a flexible coordination polymer best studied for its strong and isotropic negative thermal expansion (NTE) effect. Here we show that this NTE is actually X-ray-exposure dependent: Cd(CN)2 contracts not only on heating but also on irradiation by X-rays. This behaviour contrasts that observed in other beam-sensitive materials, for which X-ray exposure drives lattice expansion. We call this effect ‘negative X-ray expansion’ (NXE) and suggest its origin involves an interaction between X-rays and cyanide ‘flips’; in particular, we rule out local heating as a possible mechanism. Irradiation also affects the nature of a low-temperature phase transition. Our analysis resolves discrepancies in NTE coefficients reported previously on the basis of X-ray diffraction measurements, and we establish the ‘true’ NTE behaviour of Cd(CN)2 across the temperature range 150–750 K. The interplay between irradiation and mechanical response in Cd(CN)2 highlights the potential for exploiting X-ray exposure in the design of functional materials.Keywords
Funding Information
- Leverhulme Trust (RPG-2015-292)
- H2020 Marie Skłodowska-Curie Actions (641887)
- H2020 European Research Council (788144)
This publication has 50 references indexed in Scilit:
- Rational Design of Materials with Extreme Negative Compressibility: Selective Soft-Mode Frustration in KMn[Ag(CN)2]3Journal of the American Chemical Society, 2011
- Radiation damage in macromolecular crystallography: what is it and why should we care?Acta crystallographica. Section D, Structural biology, 2010
- A beginner's guide to radiation damageJournal of Synchrotron Radiation, 2009
- Observation of X-ray-induced phase transition phenomenon of cesium manganese hexacyanoferrateJournal of Physics: Conference Series, 2009
- Electronic structure, bonding and phonon modes in the negative thermal expansion materials of Cd(CN)2and Zn(CN)2Journal of Physics: Condensed Matter, 2008
- X-ray Illumination Induced Fe(II) Spin Crossover in the Prussian Blue Analogue Cesium Iron HexacyanochromateJournal of the American Chemical Society, 2006
- When X-rays modify the protein structure: radiation damage at workTrends in Biochemical Sciences, 2005
- X-ray-induced disordering of the dimerization pattern and apparent low-temperature enhancement of lattice symmetry in spinelPhysical Review B, 2002
- Structural changes, clustering, and photoinduced phase segregation inPhysical Review B, 1998
- 113Cd NMR studies of Hofmann-type clathrates and related compounds: Evidence for two room temperature orientational glassesCanadian Journal of Chemistry, 1990