E02-JEM ARM 300CF
|
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.
|
Oct 2021
|
|
I19-Small Molecule Single Crystal Diffraction
|
Open Access
Abstract: The guest-dependent flexibility of the pillared-layered metal-organic framework (MOF), Zn2bdc2dabco·X(guest), where guest = EtOH, DMF or benzene, has been examined by high-pressure single crystal X-ray diffraction. A pressure-induced structural phase transition is found for the EtOH- and DMF-included frameworks during compression in a hydrostatic medium of the guest species, which is dependent upon the nature and quantity of the guest in the channels. The EtOH-included material undergoes a phase transition from P4/mmm to C2/m at 0.69 GPa, which is accompanied by a change in the pore shape from square to rhombus via super-filling of the pores. The DMF-included material undergoes a guest-medaited phase transition from I4/mcm to P4/mmm at 0.32 GPa via disordering of the DMF guest. In contrast, the benzene-included framework features a structure with rhombus-shaped channels at ambient pressure and shows direct compression as well as negative linear compressibility parallel to the long diagonal of the channels under hydrostatic pressure. These results demonstrate the large influence of guest molecules on the phase behavior of flexible MOFs. Thus, guest-mediated framework flexibility is useful to engineering MOFs with bespoke pore shapes and compressibility.
|
Sep 2021
|
|
I09-Surface and Interface Structural Analysis
|
Anna
Regoutz
,
Alex M.
Ganose
,
Lars
Blumenthal
,
Christoph
Schlueter
,
Tien-Lin
Lee
,
Gregor
Kieslich
,
Anthony K.
Cheetham
,
Gwilherm
Kerherve
,
Ying-Sheng
Huang
,
Ruei-San
Chen
,
Giovanni
Vinai
,
Tommaso
Pincelli
,
Giancarlo
Panaccione
,
Kelvin H. L.
Zhang
,
Russell G.
Egdell
,
Johannes
Lischner
,
David O.
Scanlon
,
David J.
Payne
Diamond Proposal Number(s):
[12673]
Abstract: Theory and experiment are combined to gain an understanding of the electronic properties of OsO2, a poorly studied metallic oxide that crystallizes in the rutile structure. Hard and soft valence-band x-ray photoemission spectra of OsO2 single crystals are in broad agreement with the results of density-functional-theory calculations, aside from a feature shifted to high binding energy of the conduction band. The energy shift corresponds to the conduction electron plasmon energy measured by reflection electron energy loss spectroscopy. The plasmon satellite is reproduced by many-body perturbation theory.
|
Feb 2019
|
|
I15-Extreme Conditions
|
Diamond Proposal Number(s):
[12370]
Open Access
Abstract: We investigate the pressure-dependent mechanical behaviour of the zeolitic imidazolate framework ZIF-4 (M(im)2; M2+ = Co2+ or Zn2+, im− = imidazolate) with high pressure, synchrotron powder X-ray diffraction and mercury intrusion measurements. A displacive phase transition from a highly compressible open pore (op) phase with continuous porosity (space group Pbca, bulk modulus ∼1.4 GPa) to a closed pore (cp) phase with inaccessible porosity (space group P21/c, bulk modulus ∼3.3–4.9 GPa) is triggered by the application of mechanical pressure. Over the course of the transitions, both ZIF-4 materials contract by about 20% in volume. However, the threshold pressure, the reversibility and the immediate repeatability of the phase transition depend on the metal cation. ZIF-4(Zn) undergoes the op–cp phase transition at a hydrostatic mechanical pressure of only 28 MPa, while ZIF-4(Co) requires about 50 MPa to initiate the transition. Interestingly, ZIF-4(Co) fully returns to the op phase after decompression, whereas ZIF-4(Zn) remains in the cp phase after pressure release and requires subsequent heating to switch back to the op phase. These variations in high pressure behaviour can be rationalised on the basis of the different electron configurations of the respective M2+ ions (3d10 for Zn2+ and 3d7 for Co2+). Our results present the first examples of op–cp phase transitions (i.e. breathing transitions) of ZIFs driven by mechanical pressure and suggest potential applications of these functional materials as shock absorbers, nanodampers, or in mechanocalorics.
|
Jan 2018
|
|
I19-Small Molecule Single Crystal Diffraction
|
Shijing
Sun
,
Zeyu
Deng
,
Yue
Wu
,
Fengxia
Wei
,
Furkan
Halis Isikgor
,
Federico
Brivio
,
Michael W.
Gaultois
,
Jianyong
Ouyang
,
Paul D.
Bristowe
,
Anthony K.
Cheetham
,
Gregor
Kieslich
Diamond Proposal Number(s):
[14165]
Abstract: We investigate the variable temperature (100–450 K) and high-pressure (p = ambient − 0.74 GPa) crystal chemistry of the black perovskite formamidinium lead iodide, [(NH2)2CH]PbI3, using single crystal X-ray diffraction. In both cases we find a phase transition to a tetragonal phase. Our experimental results are combined with first principles calculations, providing information about the electronic properties of [(NH2)2CH]PbI3 as well as the most probable orientation of the [(NH2)2CH]+ cations.
|
Jun 2017
|
|
I19-Small Molecule Single Crystal Diffraction
|
Diamond Proposal Number(s):
[8521]
Abstract: Eleven novel coordination compounds, composed of chrysazin (1,8-dihydroxyanthraquinone) and different first-row transition metals (Fe, Co, Ni, Cu), were synthesised and the structures determined by single-crystal X-ray diffraction. The synthetic trends were investigated using high-throughput synthesis under systematic variation of concentration and reagent stoichiometry: for complexes containing Co, Ni or Cu crystallisation was improved by low ligand[thin space (1/6-em)]:[thin space (1/6-em)]metal ratios, while the effect of concentration depended on the metal used. The compounds crystallise as discrete clusters, apart from two, which contain long Cu–O bonds which may allow the two compounds to be considered one-dimensional coordination polymers. One of these compounds shows a distance between aryl rings of less than 3.26 Å, which is shorter than that in graphite, suggesting applications as an organic–inorganic semiconductor. The compound was found to be insulating by single-crystal and powder AC-impedance measurements, and this result is discussed with reference to the electronic structure calculated using density-functional theory.
|
May 2016
|
|
B18-Core EXAFS
|
Thomas
Bennett
,
Yuanzheng
Yue
,
Peng
Li
,
Ang
Qiao
,
Haizheng
Tao
,
Neville
Greaves
,
Tom
Richards
,
Giulio
Lampronti
,
Simon
Redfern
,
Frédéric
Blanc
,
Omar K.
Farha
,
Joseph T.
Hupp
,
Anthony K.
Cheetham
,
David
Keen
Diamond Proposal Number(s):
[14249]
Open Access
Abstract: Crystalline solids dominate the field of metal-organic frameworks (MOFs), with access to the liquid and glass states of
matter usually prohibited by relatively low temperatures of thermal decomposition. In this work, we give due consideration
to framework chemistry and topology to expand the phenomenon of the melting of three-dimensional MOFs, linking
crystal chemistry to framework melting temperature and kinetic fragility of the glass-forming liquids. Here we show that
melting temperatures can be lowered by altering the chemistry of the crystalline MOF state, which provides a route to
facilitate the melting of other MOFs. The glasses formed upon vitrification are chemically and structurally distinct from
the three other existing categories of melt-quenched glasses (inorganic non-metallic, organic and metallic), and retain the
basic metal-ligand connectivity of crystalline MOFs, which connects their mechanical properties to starting chemical
composition. The transfer of functionality from crystal to glass points towards new routes to tunable, functional hybrid
glasses.
|
Feb 2016
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Diamond Proposal Number(s):
[9661]
Abstract: Understanding the driving forces controlling crys-tallization is essential for the efficient synthesis and design ofnew materials,particularly metal–organic frameworks(MOFs), where mild solvothermal synthesis often allowsaccess to various phases from the same reagents.Using high-energy in situ synchrotron X-ray powder diffraction, wemonitor the crystallization of lithium tartrate MOFs,observingthe successive crystallization and dissolution of three compet-ing phases in one reaction. By determining rate constants andactivation energies,wefully quantify the reaction energylandscape,gaining important predictive power for the choice ofreaction conditions.Different reaction rates are explained bythe structural relationships between the products and thereactants;larger changes in conformation result in higheractivation energies.The methods we demonstrate can easily beapplied to other materials,opening the door to agreaterunderstanding of crystallization in general.
|
Feb 2016
|
|
I19-Small Molecule Single Crystal Diffraction
|
Abstract: Dense formate frameworks with a perovskite-like architecture exhibit multiferroic behavior and tunable mechanical properties. In such materials, interactions between the protonated amine and the metal–formate cavity have a large impact on the mechanical properties. We use complementary single-crystal X-ray diffraction and 1H solid state nuclear magnetic resonance spectroscopy to investigate amine–cavity interactions in [NH3NH2]Zn(HCOO)3. The results suggest that these interactions can be described as salt bridges similar to those in proteins and artificially synthesized helical polymers, where ionic interactions and hydrogen bonds are present at the same time. Nanoindentation and high-pressure single-crystal X-ray diffraction were used to study the mechanical properties of [NH3NH2]Zn(HCOO)3, yielding elastic moduli of E001 = 26.5 GPa and E110 = 24.6 GPa and a bulk modulus of K = 19 GPa. The mechanical properties suggest that, despite the relatively low packing density of [NH3NH2]Zn(HCOO)3, the amine–cavity interactions strengthen the framework significantly in comparison with related materials.
|
Jan 2016
|
|
I19-Small Molecule Single Crystal Diffraction
|
Diamond Proposal Number(s):
[8580]
Abstract: The mechanical properties of calcium fumarate trihydrate, a 1D coordination polymer considered for use as a calcium source for food and beverage enrichment, have been determined via nanoindentation and high-pressure X-ray diffraction with single crystals. The nanoindentation studies reveal that the elastic modulus (16.7–33.4 GPa, depending on crystallographic orientation), hardness (1.05–1.36 GPa), yield stress (0.70–0.90 GPa), and creep behavior (0.8–5.8 nm/s) can be rationalized in view of the anisotropic crystal structure; factors include the directionality of the inorganic Ca–O–Ca chain and hydrogen bonding, as well as the orientation of the fumarate ligands. High-pressure single-crystal X-ray diffraction studies show a bulk modulus of ∼20 GPa, which is indicative of elastic recovery intermediate between small molecule drug crystals and inorganic pharmaceutical ingredients. The combined use of nanoindentation and high-pressure X-ray diffraction techniques provides a complementary experimental approach for probing the critical mechanical properties related to tableting of these dietary supplements.
|
Nov 2015
|
|
