E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[20198]
Open Access
Abstract: Intentionally disordered metal–organic frameworks (MOFs) display rich functional behaviour. However, the characterisation of their atomic structures remains incredibly challenging. X-ray pair distribution function techniques have been pivotal in determining their average local structure but are largely insensitive to spatial variations in the structure. Fe-BTC (BTC = 1,3,5-benzenetricarboxylate) is a nanocomposite MOF, known for its catalytic properties, comprising crystalline nanoparticles and an amorphous matrix. Here, we use scanning electron diffraction to first map the crystalline and amorphous components to evaluate domain size and then to carry out electron pair distribution function analysis to probe the spatially separated atomic structure of the amorphous matrix. Further Bragg scattering analysis reveals systematic orientational disorder within Fe-BTC’s nanocrystallites, showing over 10° of continuous lattice rotation across single particles. Finally, we identify candidate unit cells for the crystalline component. These independent structural analyses quantify disorder in Fe-BTC at the critical length scale for engineering composite MOF materials.
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May 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Open Access
Abstract: Membranes with ultrahigh permeance and practical selectivity could greatly decrease the cost of difficult industrial gas separations, such as CH4/N2 separation. Advanced membranes made from porous materials, such as metal–organic frameworks, can achieve a good gas separation performance, although they are typically formed on support layers or mixed with polymeric matrices, placing limitations on gas permeance. Here an amorphous glass foam, agfZIF-62, wherein a, g and f denote amorphous, glass and foam, respectively, was synthesized by a polymer-thermal-decomposition-assisted melting strategy, starting from a crystalline zeolitic imidazolate framework, ZIF-62. The thermal decomposition of incorporated low-molecular-weight polyethyleneimine evolves CO2, NH3 and H2O gases, creating a large number and variety of pores. This greatly increases pore interconnectivity but maintains the crystalline ZIF-62 ultramicropores, allowing ultrahigh gas permeance and good selectivity. A self-supported circular agfZIF-62 with a thickness of 200–330 µm and area of 8.55 cm2 was used for membrane separation. The membranes perform well, showing a CH4 permeance of 30,000–50,000 gas permeance units, approximately two orders of magnitude higher than that of other reported membranes, with good CH4/N2 selectivity (4–6).
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May 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Mohamed. A.
Ali
,
Wessel M. W.
Winters
,
Moushira A.
Mohamed
,
Dezhi
Tan
,
Guojun
Zheng
,
Rasmus S. K.
Madsen
,
Oxana V.
Magdysyuk
,
Maria
Diaz-Lopez
,
Biao
Cai
,
Nan
Gong
,
Yijue
Xu
,
Ivan
Hung
,
Zhehong
Gan
,
Sabyasachi
Sen
,
Hong-Tao
Sun
,
Thomas D.
Bennett
,
Xiaofeng
Liu
,
Yuanzheng
Yue
,
Jianrong
Qiu
Diamond Proposal Number(s):
[30401]
Abstract: Glassy metal coordination compounds (MCC) [e.g., metal-organic framework (MOF), coordination polymer, and metal inorganic-organic complex (MIOC)] are emerging members of the hybrid glass family. So far, a limited number of crystalline MCCs can be converted into glasses by the melt-quenching. Here, we report a universal wet-chemistry method, by which the super-sized supramolecular MIOC glasses can be synthesized from non-meltable MOFs. Alcohol and acid were used as agents to inhibit crystallization. The MIOC glasses demonstrate unique features including high transparency, shaping capability, and anisotropic network. Directional photoluminescence with a large polarization ratio (~47%) was observed from samples doped with organic dyes. This crystallization-suppressing approach enables fabrication of MCC glasses, which cannot be achieved by conventional vitrification methods, and thus allows for exploring new MCC glasses possessing photonic functionalities.
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Feb 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Alice M.
Bumstead
,
Celia
Castillo-Blas
,
Ignas
Pakamore
,
Michael F.
Thorne
,
Adam F.
Sapnik
,
Ashleigh M.
Chester
,
Georgina
Robertson
,
Daniel J. M.
Irving
,
Philip A.
Chater
,
David A.
Keen
,
Ross S.
Forgan
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: The chemistries that can be incorporated within melt-quenched zeolitic imidazolate framework (ZIF) glasses are currently limited. Here we describe the preparation of a previously unknown purine-containing ZIF which we name ZIF-UC-7. We find that it melts and forms a glass at one of the lowest temperatures reported for 3D hybrid frameworks.
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Dec 2022
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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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I11-High Resolution Powder Diffraction
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Michael F.
Thorne
,
Celia
Castillo Blas
,
Lauren N.
Mchugh
,
Alice M.
Bumstead
,
Georgina
Robertson
,
Adam F.
Sapnik
,
Chloe S.
Coates
,
Farheen N.
Sayed
,
Clare P.
Grey
,
David A.
Keen
,
Martin
Etter
,
Ivan
Da Silva
,
Krunoslav
Užarević
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[28349]
Open Access
Abstract: The structure of a new ZIF-8 polymorph with quartz topology (qtz) is reported. This qtz-[Zn(mIm)2] phase was obtained by mechanically amorphising crystalline ZIF-8, before heating the resultant amorphous phase to between 282 and 316 °C. The high temperature phase structure was obtained from X-ray powder diffraction, and its thermal behaviour, CO2 gas sorption properties and dye adsorption ability were investigated.
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Sep 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[20038]
Open Access
Abstract: The rational design of disordered frameworks is an appealing route to target functional materials. However, intentional realisation of such materials relies on our ability to readily characterise and quantify structural disorder. Here, we use multivariate analysis of pair distribution functions to fingerprint and quantify the disorder within a series of compositionally identical metal–organic frameworks, possessing different crystalline, disordered, and amorphous structures. We find this approach can provide powerful insight into the kinetics and mechanism of structural collapse that links these materials. Our methodology is also extended to a very different system, namely the melting of a zeolitic imidazolate framework, to demonstrate the potential generality of this approach across many areas of disordered structural chemistry.
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Apr 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Alice M.
Bumstead
,
Ignas
Pakamore
,
Kieran D.
Richards
,
Michael F.
Thorne
,
Sophia S.
Boyadjieva
,
Celia
Castillo-Blas
,
Lauren N.
Mchugh
,
Adam F.
Sapnik
,
Dean S.
Keeble
,
David A.
Keen
,
Rachel C.
Evans
,
Ross S.
Forgan
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Abstract: Melt-quenched metal–organic framework (MOF) glasses have gained significant interest as the first new category of glass reported in 50 years. In this work, an amine-functionalized zeolitic imidazolate framework (ZIF), denoted ZIF-UC-6, was prepared and demonstrated to undergo both melting and glass formation. The presence of an amine group resulted in a lower melting temperature compared to other ZIFs, while also allowing material properties to be tuned by post-synthetic modification (PSM). As a prototypical example, the ZIF glass surface was functionalized with octyl isocyanate, changing its behavior from hydrophilic to hydrophobic. PSM therefore provides a promising strategy for tuning the surface properties of MOF glasses.
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Feb 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[20038]
Open Access
Abstract: Four novel dicyanamide-containing hybrid organic-inorganic ABX3 structures are reported, and the thermal behaviour of a series of nine perovskite and non-perovskite [AB(N(CN)2)3] (A = (C3H7)4N, (C4H9)4N, (C5H11)4N; B = Co, Fe, Mn). Structure-property relationships are investigated by varying both A-site organic and B-site transition metal cations. In particular, increasing the size of the A-site cation from (C3H7)4N → (C4H9)4N → (C5H11)4N was observed to result in a decrease in Tm through an increase in ΔSf. Consistent trends in Tm with metal replacement are observed with each A-site cation, with Co < Fe < Mn. The majority of the melts formed were found to recrystallise partially upon cooling, though glasses could be formed through a small degree of organic linker decomposition. Total scattering methods are used to provide a greater understanding of the melting mechanism
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Jan 2022
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E02-JEM ARM 300CF
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Jingwei
Hou
,
Peng
Chen
,
Atul
Shukla
,
Andraž
Krajnc
,
Tiesheng
Wang
,
Xuemei
Li
,
Rana
Doasa
,
Luiz H. G.
Tizei
,
Bun
Chan
,
Duncan N.
Johnstone
,
Rijia
Lin
,
Tobias U.
Schülli
,
Isaac
Martens
,
Dominique
Appadoo
,
Mark
S'Ari
,
Zhiliang
Wang
,
Tong
Wei
,
Shih-Chun
Lo
,
Mingyuan
Lu
,
Shichun
Li
,
Ebinazar B.
Namdas
,
Gregor
Mali
,
Anthony K.
Cheetham
,
Sean M.
Collins
,
Vicki
Chen
,
Lianzhou
Wang
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[21980, 25140]
Abstract: Lead halide perovskite (LHP) semiconductors show exceptional optoelectronic properties. Barriers for their applications, however, lie in their polymorphism, instability to polar solvents, phase segregation, and susceptibility to the leaching of lead ions. We report a family of scalable composites fabricated through liquid-phase sintering of LHPs and metal-organic framework glasses. The glass acts as a matrix for LHPs, effectively stabilizing nonequilibrium perovskite phases through interfacial interactions. These interactions also passivate LHP surface defects and impart bright, narrow-band photoluminescence with a wide gamut for creating white light-emitting diodes (LEDs). The processable composites show high stability against immersion in water and organic solvents as well as exposure to heat, light, air, and ambient humidity. These properties, together with their lead self-sequestration capability, can enable breakthrough applications for LHPs.
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Oct 2021
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