Abstract
Emerging nanoporous materials, such as metal-organic frameworks (MOFs), are promising low-k dielectrics central to next-generation electronics and high-speed communication. Hitherto, the dielectric characterization of MOFs is scarce, with very limited experimental data for guiding new materials design and synthesis. Herein we demonstrate the efficacy of high-resolution synchrotron infrared (IR) specular reflectance experiments to study the dynamic dielectric properties of a flexible MOF structure: bistable MIL-53(Al) that exhibits switching between a large pore (LP) and a narrow pore (NP) architecture. We show that the ratio of LP:NP content of a polycrystalline sample can be changed via increased mechanical stress applied for pelletizing the MIL-53(Al) powder. We quantify the frequency-dependent dielectric constants over ∼1 to 120 THz, identifying all dielectric transitions as a function of stress and phase mixtures, showing how porosity modifies MOF's dielectric properties.
Original language | English |
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Pages (from-to) | 5035-5040 |
Number of pages | 6 |
Journal | Journal of Physical Chemistry Letters |
Volume | 8 |
Issue number | 20 |
DOIs | |
State | Published - Oct 19 2017 |
Externally published | Yes |
Funding
We acknowledge the Diamond Light Source for the provision of beamtime SM14902 at B22 MIRIAM. K.T. thanks the Balliol College Scholarship for supporting his postgraduate studies. J.C.T. thanks the Engineering and Physical Sciences Research Council (EPSRC) for research funding (EP/N014960/1). M.R.R. acknowledges the EPSRC DTA and STFC CMSD Award (13-05) for postgraduate funding; M.R.R. also thanks the EPSRC for a Doctoral Prize Fellowship. A.K.C. thanks the Samsung GRO for postgraduate funding. We thank the Research Complex at Harwell (RCaH), Oxfordshire, for access to the advanced materials characterization suite. We are grateful to Dr. Gavin Stenning and Dr. Marek Jura (R53 Materials Characterization Lab) at the ISIS Rutherford Appleton Laboratory for the X-ray characterization facilities.