E02-JEM ARM 300CF
I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[16983, 19130, 20195, 21979, 22395, 20038]
Open Access
Abstract: Characterization of nanoscale changes in the atomic structure of amorphous materials is a profound challenge. Established X-ray and neutron total scattering methods typically provide sufficient signal quality only over macroscopic volumes. Pair distribution function analysis using electron scattering (ePDF) in the scanning transmission electron microscope (STEM) has emerged as a method of probing nanovolumes of these materials, but inorganic glasses as well as metal–organic frameworks (MOFs) and many other materials containing organic components are characteristically prone to irreversible changes after limited electron beam exposures. This beam sensitivity requires ‘low-dose’ data acquisition to probe inorganic glasses, amorphous and glassy MOFs, and MOF composites. Here, we use STEM-ePDF applied at low electron fluences (10 e-/Å2) combined with unsupervised machine learning methods to map changes in the short-range order with ca. 5 nm spatial resolution in a composite material consisting of a zeolitic imidazolate framework glass agZIF-62 and a 0.67([Na2O]0.9[P2O5])-0.33([AlO3/2][AlF3]1.5) inorganic glass. STEM-ePDF enables separation of MOF and inorganic glass domains from atomic structure differences alone, showing abrupt changes in atomic structure at interfaces with interatomic correlation distances seen in X-ray PDF preserved at the nanoscale. These findings underline that the average bulk amorphous structure is retained at the nanoscale in the growing family of MOF glasses and composites, a previously untested assumption in PDF analyses crucial for future non-crystalline nanostructure engineering.
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Oct 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Louis
Longley
,
Courtney
Calahoo
,
René
Limbach
,
Yang
Xia
,
Joshua M.
Tuffnell
,
Adam F.
Sapnik
,
Michael F.
Thorne
,
Dean S.
Keeble
,
David A.
Keen
,
Lothar
Wondraczek
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Metal-organic framework (MOF) glasses have become a subject of interest as a distinct category of melt quenched glass, and have potential applications in areas such as ion transport and sensing. In this paper we show how MOF glasses can be combined with inorganic glasses in order to fabricate a new family of materials composed of both MOF and inorganic glass domains. We use an array of experimental techniques to propose the bonding between inorganic and MOF domains, and show that the composites produced are more mechanically pliant than the inorganic glass itself.
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Nov 2020
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Recently, there has been growing interest in the amorphous states of metal–organic frameworks (MOFs). Particular focus has been given to melt-quenched MOF glasses. In this work, to improve our understanding of the factors influencing melting, the thermal response of four closely related zeolitic imidazolate frameworks (ZIFs) was studied. Electron withdrawing ligands were found to lower both the melting and glass transition temperatures, providing a promising strategy for improving the processability of MOFs in the liquid state. Crucially, dense frameworks appear to be essential for melting, with their presence also initiating the melting of open pore frameworks. This opens up the rich polymorphic landscape of ZIFs to the preparation of novel MOF liquids and glasses.
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May 2020
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[16983, 19130, 20195, 21979]
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Aug 2019
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E02-JEM ARM 300CF
I15-1-X-ray Pair Distribution Function (XPDF)
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Jingwei
Hou
,
Christopher W.
Ashling
,
Sean M.
Collins
,
Andraž
Krajnc
,
Chao
Zhou
,
Louis
Longley
,
Duncan N.
Johnstone
,
Philip
Chater
,
Shichun
Li
,
Marie-Vanessa
Coulet
,
Philip L.
Llewellyn
,
François-Xavier
Coudert
,
David
Keen
,
Paul A.
Midgley
,
Gregor
Mali
,
Vicki
Chen
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[171151, 19130, 16983]
Open Access
Abstract: The majority of research into metal-organic frameworks (MOFs) focuses on their crystalline nature. Recent research has revealed solid-liquid transitions within the family, which we use here to create a class of functional, stable and porous composite materials. Described herein is the design, synthesis, and characterisation of MOF crystal-glass composites, formed by dispersing crystalline MOFs within a MOF-glass matrix. The coordinative bonding and chemical structure of a MIL-53 crystalline phase are preserved within the ZIF-62 glass matrix. Whilst separated phases, the interfacial interactions between the closely contacted microdomains improve the mechanical properties of the composite glass. More significantly, the high temperature open pore phase of MIL-53, which spontaneously transforms to a narrow pore upon cooling in the presence of water, is stabilised at room temperature in the crystal-glass composite. This leads to a significant improvement of CO2 adsorption capacity.
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Jun 2019
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I15-1-X-ray Pair Distribution Function (XPDF)
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Jiayang
Zhang
,
Louis
Longley
,
Hao
Liu
,
Christopher W.
Ashling
,
Philip A.
Chater
,
Kevin A.
Beyer
,
Karena W.
Chapman
,
Haizheng
Tao
,
David A.
Keen
,
Thomas D.
Bennett
,
Yuanzheng
Yue
Diamond Proposal Number(s):
[171151]
Abstract: A pronounced enthalpy release occurs around 1.38 Tg in the prototypical metal-organic framework glass formed from ZIF-4 [Zn(C3H3N2)2], but there is no sign for any crystallization (i.e., long-range ordering) taking place. This behavior is in strong contrast to that for other families of melt-quenched glasses.
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Feb 2019
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I22-Small angle scattering & Diffraction
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Louis
Longley
,
Sean M.
Collins
,
Shichun
Li
,
Glen J.
Smales
,
Ilknur
Erucar
,
Ang
Qiao
,
Jingwei
Hou
,
Cara M.
Doherty
,
Aaron W.
Thornton
,
Anita J.
Hill
,
Xiao
Yu
,
Nicholas J.
Terrill
,
Andrew J.
Smith
,
Seth M.
Cohen
,
Paul A.
Midgley
,
David A.
Keen
,
Shane G.
Telfer
,
Thomas
Bennett
Diamond Proposal Number(s):
[18236]
Open Access
Abstract: Recent demonstrations of melting in the metal–organic framework (MOF) family have created interest in the interfacial domain between inorganic glasses and amorphous organic polymers. The chemical and physical behaviour of porous hybrid liquids and glasses is of particular interest, though opportunities are limited by the inaccessible melting temperatures of many MOFs. Here, we show that the processing technique of flux melting, ‘borrowed’ from the inorganic domain, may be applied in order to melt ZIF-8, a material which does not possess an accessible liquid state in the pure form. Effectively, we employ the high-temperature liquid state of one MOF as a solvent for a secondary, non-melting MOF component. Differential scanning calorimetry, small- and wide-angle X-ray scattering, electron microscopy and X-ray total scattering techniques are used to show the flux melting of the crystalline component within the liquid. Gas adsorption and positron annihilation lifetime spectroscopy measurements show that this results in enhanced, accessible porosity to a range of guest molecules in the resultant flux melted MOF glass.
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Feb 2019
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I15-1-X-ray Pair Distribution Function (XPDF)
I22-Small angle scattering & Diffraction
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Chao
Zhou
,
Louis
Longley
,
Andraž
Krajnc
,
Glen J.
Smales
,
Ang
Qiao
,
Ilknur
Erucar
,
Cara M.
Doherty
,
Aaron W.
Thornton
,
Anita J.
Hill
,
Christopher W.
Ashling
,
Omid T.
Qazvini
,
Seok J.
Lee
,
Philip A.
Chater
,
Nicholas J.
Terrill
,
Andrew J.
Smith
,
Yuanzheng
Yue
,
Gregor
Mali
,
David A.
Keen
,
Shane G.
Telfer
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[18236]
Open Access
Abstract: To date, only several microporous, and even fewer nanoporous, glasses have been produced, always via post synthesis acid treatment of phase separated dense materials, e.g. Vycor glass. In contrast, high internal surface areas are readily achieved in crystalline materials, such as metal-organic frameworks (MOFs). It has recently been discovered that a new family of melt quenched glasses can be produced from MOFs, though they have thus far lacked the accessible and intrinsic porosity of their crystalline precursors. Here, we report the first glasses that are permanently and reversibly porous toward incoming gases, without post-synthetic treatment. We characterize the structure of these glasses using a range of experimental techniques, and demonstrate pores in the range of 4 – 8 Å. The discovery of MOF glasses with permanent accessible porosity reveals a new category of porous glass materials that are elevated beyond conventional inorganic and organic porous glasses by their diversity and tunability.
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Nov 2018
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[171151]
Abstract: In this work, we explore the thermodynamic evolution in a melt-quenched metal–organic framework glass, formed from ZIF-62 upon heating to the melting point (Tm), and subsequent enthalpy relaxation. The temperature dependence of the difference in Gibbs free energy between the liquid and crystal states of ZIF-62 in the temperature range from the glass transition temperature (Tg) to Tm is found to be weaker than those of other types of glasses, e.g., metallic glasses. Additionally, we find that the stretched exponent of the enthalpy relaxation function in the glass varies significantly (β = 0.44–0.76) upon changing the extent of sub-Tg annealing, compared to metallic and oxide glasses with similar Tgs, suggesting a high degree of structural heterogeneity. Pair distribution function results suggest no significant structural changes during the sub-Tg relaxation in ZIF-62 glass.
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Jun 2018
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I15-1-X-ray Pair Distribution Function (XPDF)
I22-Small angle scattering & Diffraction
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Louis
Longley
,
Sean
Collins
,
Chao
Zhou
,
Glen J.
Smales
,
Sarah E.
Norman
,
Nick J.
Brownbill
,
Christopher W.
Ashling
,
Philip A.
Chater
,
Robert
Tovey
,
Carola-Bibiane
Schönlieb
,
Thomas F.
Headen
,
Nicholas J.
Terrill
,
Yuanzheng
Yue
,
Andrew J.
Smith
,
Frédéric
Blanc
,
David
Keen
,
Paul A.
Midgley
,
Thomas
Bennett
Diamond Proposal Number(s):
[171151, 18236]
Open Access
Abstract: The liquid and glass states of metal–organic frameworks (MOFs) have recently become of interest due to the potential for liquid-phase separations and ion transport, alongside the fundamental nature of the latter as a new, fourth category of melt-quenched glass. Here we show that the MOF liquid state can be blended with another MOF component, resulting in a domain structured MOF glass with a single, tailorable glass transition. Intra-domain connectivity and short range order is confirmed by nuclear magnetic resonance spectroscopy and pair distribution function measurements. The interfacial binding between MOF domains in the glass state is evidenced by electron tomography, and the relationship between domain size and Tg investigated. Nanoindentation experiments are also performed to place this new class of MOF materials into context with organic blends and inorganic alloys.
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Jun 2018
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