Identifying the Role of Terahertz Vibrations in Metal-Organic Frameworks: From Gate-Opening Phenomenon to Shear-Driven Structural Destabilization

DOI: 10.1103/PhysRevLett.113.215502
PMID: 25479503

Authors: Matthew Ryder (Department of Engineering Science, University of Oxford) , Bartolomeo Civalleri (University of Turin) , Thomas Bennett (Department of Materials Science and Metallurgy, University of Cambridge) , Sebastian Henke (Department of Materials Science and Metallurgy, University of Cambridge) , Svemir Rudic (ISIS Facility, Rutherford Appleton Laboratory) , Gianfelice Cinque (Diamond Light Source) , Felix Fernandez-alonso (ISIS Facility, Rutherford Appleton Laboratory) , Jin-chong Tan (Department of Engineering Science, University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Letters , VOL 113 (21)

State: Published (Approved)
Published: November 2014
Diamond Proposal Number(s): 8236 , 9388

Abstract: We present an unambiguous identification of low-frequency terahertz vibrations in the archetypal imidazole-based metal-organic framework (MOF) materials: ZIF-4, ZIF-7, and ZIF-8, all of which adopt a zeolite-like nanoporous structure. Using inelastic neutron scattering and synchrotron radiation far-infrared absorption spectroscopy, in conjunction with density functional theory (DFT), we have pinpointed all major sources of vibrational modes. Ab initio DFT calculations revealed the complex nature of the collective THz modes, which enable us to establish detailed correlations with experiments. We discover that low-energy conformational dynamics offers multiple pathways to elucidate novel physical phenomena observed in MOFs. New evidence demonstrates that THz modes are intrinsically linked, not only to anomalous elasticity underpinning gate-opening and pore-breathing mechanisms, but also to shear-induced phase transitions and the onset of structural instability.

Subject Areas: Physics, Materials


Instruments: B22-Multimode InfraRed imaging And Microspectroscopy