Achieving high battery performance from low-cost, easily synthesisable electrode materials is crucial for advancing energy storage technologies. Metal organic frameworks (MOFs) combining inexpensive transition metals and organic ligands are promising candidates for high-capacity cathodes. Iron-chloranilate-water frameworks are herein reported to be produced in aqueous media under mild conditions.
View Article and Find Full Text PDFVan der Waals (vdW) magnets offer unique opportunities for exploring magnetism in the 2D limit. Metal-organic magnets (MOM) are of particular interest as the functionalisation of organic ligands can control their physical properties. Here, we demonstrate tuning of mechanical and magnetic function of a noncollinear vdW ferromagnet, NiCl(btd) (btd = 2,1,3-benzothiadiazole), through creating solid-solutions with the oxygen-substituted analogue ligand 2,1,3-benzoxadiazole (bod).
View Article and Find Full Text PDFSpin liquids are a paradigmatic example of a nontrivial state of matter. The search for new spin liquids is a key interdisciplinary challenge. Geometrical frustration-where the geometry of the net that the spins occupy precludes the generation of a simple ordered state-is a particularly fruitful way to generate these intrinsically disordered states.
View Article and Find Full Text PDFMetal thiocyanates were some of the first pseudohalide compounds to be discovered and adopt a diverse range of structures. This review describes the structures, properties, and syntheses of the known binary and ternary metal thiocyanates. It provides a categorization of their diverse structures and connects them to the structures of atomic inorganic materials.
View Article and Find Full Text PDFVan der Waals (vdW) magnets both allow exploration of fundamental 2D physics and offer a route toward exploiting magnetism in next generation information technology, but vdW magnets with complex, noncollinear spin textures are currently rare. We report here the syntheses, crystal structures, magnetic properties and magnetic ground states of four bulk vdW metal-organic magnets (MOMs): FeCl(pym), FeCl(btd), NiCl(pym), and NiCl(btd), pym = pyrimidine and btd = 2,1,3-benzothiadiazole. Using a combination of neutron diffraction and bulk magnetometry we show that these materials are noncollinear magnets.
View Article and Find Full Text PDFWe report the magnetic structure and properties of a thiocyanate-based honeycomb magnet [Na(OH)]Mn(NCS) which crystallises in the unusual low-symmetry trigonal space group 3̄. Magnetic measurements on powder samples show this material is an antiferromagnet (ordering temperature = 18.1(6) K) and can be described by nearest neighbour antiferromagnetic interactions = -11.
View Article and Find Full Text PDFTwo-dimensional metal-organic nanosheets (MONs) have emerged as attractive alternatives to their three-dimensional metal-organic framework (MOF) counterparts for heterogeneous catalysis due to their greater external surface areas and higher accessibility of catalytically active sites. Zr MONs are particularly prized because of their chemical stability and high Lewis and Brønsted acidities of the Zr clusters. Herein, we show that careful control over modulated self-assembly and exfoliation conditions allows the isolation of the first example of a two-dimensional nanosheet wherein Zr clusters are linked by dicarboxylate ligands.
View Article and Find Full Text PDFRoom-temperature magnetically switchable materials play a vital role in current and upcoming quantum technologies, such as spintronics, molecular switches, and data storage devices. The increasing miniaturization of device architectures produces a need to develop analytical tools capable of precisely probing spin information at the single-particle level. In this work, we demonstrate a methodology using negatively charged nitrogen vacancies (NV) in fluorescent nanodiamond (FND) particles to probe the magnetic switching of a spin crossover (SCO) metal-organic framework (MOF), [Fe(1,6-naphthyridine)(Ag(CN))] material (), and a single-molecule photomagnet [X(18-crown-6)(HO)]Fe(CN)·2HO, where X = Eu and Dy (materials and , respectively), in response to heat, light, and electron beam exposure.
View Article and Find Full Text PDFSpin-active nanomaterials play a vital role in current and upcoming quantum technologies, such as spintronics, data storage and computing. To advance the design and application of these materials, methods to link size, shape, structure, and chemical composition with functional magnetic properties at the nanoscale level are needed. In this work, we combine the power of two local probes, namely, Nitrogen Vacancy (NV) spin-active defects in diamond and an electron beam, within experimental platforms used in electron microscopy.
View Article and Find Full Text PDFMetal-organic frameworks (MOFs) are a rapidly growing class of materials that offer great promise in various applications. However, the synthesis remains challenging: for example, a range of crystal structures can often be accessed from the same building blocks, which complicates the phase selectivity. Likewise, the high sensitivity to slight changes in synthesis conditions may cause reproducibility issues.
View Article and Find Full Text PDFWe review comprehensive observations of electromagnetic ion cyclotron (EMIC) wave-driven energetic electron precipitation using data collected by the energetic electron detector on the Electron Losses and Fields InvestigatioN (ELFIN) mission, two polar-orbiting low-altitude spinning CubeSats, measuring 50-5000 keV electrons with good pitch-angle and energy resolution. EMIC wave-driven precipitation exhibits a distinct signature in energy-spectrograms of the precipitating-to-trapped flux ratio: peaks at >0.5 MeV which are abrupt (bursty) (lasting ∼17 s, or ) with significant substructure (occasionally down to sub-second timescale).
View Article and Find Full Text PDFAMX compounds are structurally diverse, a notable example being the post-perovskite structure which adopts a two-dimensional framework with corner- and edge-sharing octahedra. Few molecular post-perovskites are known and of these, none have reported magnetic structures. Here we report the synthesis, structure and magnetic properties of molecular post-perovskites: CsNi(NCS), a thiocyanate framework, and two new isostructural analogues CsCo(NCS) and CsMn(NCS).
View Article and Find Full Text PDFCrystalline materials are often considered to have rigid periodic lattices, while soft materials are associated with flexibility and nonperiodicity. The continuous evolution of metal-organic frameworks (MOFs) has erased the boundaries between these two distinct conceptions. Flexibility, disorder, and defects have been found to be abundant in MOF materials with imperfect crystallinity, and their intricate interplay is poorly understood because of the limited strategies for characterizing disordered structures.
View Article and Find Full Text PDFTwo-coordinate transition metal complexes are exciting candidates for single-molecule magnets (SMMs) because their highly axial coordination environments lead to sizeable magnetic anisotropy. We report a series of five structurally related two-coordinate Fe(II) -terphenyl complexes (4-R-2,6-XylCH)Fe [R = Bu (1), SiMe (2), H (3), Cl (4), CF (5)] where, by changing the functionalisation of the -substituent (R), we alter their magnetic function. All five complexes are field-induced single-molecule magnets, with relaxation rates that are well-described by a combination of direct and Raman mechanisms.
View Article and Find Full Text PDFMetal-organic frameworks (MOFs) can be constructed using conventional molecular linkers or polymeric linkers (polyMOFs), but the relationship and relative properties of these related materials remain understudied. As an intermediate between these two extremes, a library of oligomeric ligand precursors (dimers, trimers) was used to prepare a series of oligomeric-linker MOFs (oligoMOFs) based on the prototypical IRMOF-1 system. IRMOF-1 was found to be remarkably tolerant to a wide variety of oligomeric linkers, the use of which greatly enhanced the MOF yield and prevented framework interpenetration.
View Article and Find Full Text PDFThe structures of Zr and Hf metal-organic frameworks (MOFs) are very sensitive to small changes in synthetic conditions. One key difference affecting the structure of UiO MOF phases is the shape and nuclearity of Zr or Hf metal clusters acting as nodes in the framework; although these clusters are crucial, their evolution during MOF synthesis is not fully understood. In this paper, we explore the nature of Hf metal clusters that form in different reaction solutions, including in a mixture of DMF, formic acid, and water.
View Article and Find Full Text PDFWe report four new A-site vacancy ordered thiocyanate double double perovskites, , A = K, NH , CH(NH) (MeNH ) and C(NH) (Gua), including the first examples of thiocyanate perovskites containing organic A-site cations. We show, using a combination of X-ray and neutron diffraction, that the structure of these frameworks depends on the A-site cation, and that these frameworks possess complex vacancy-ordering patterns and cooperative octahedral tilts distinctly different from atomic perovskites. Density functional theory calculations uncover the energetic origin of these complex orders and allow us to propose a simple rule to predict favoured A-site cation orderings for a given tilt sequence.
View Article and Find Full Text PDFBackground: Engagement with conventional weight management group programmes is low.
Objective: To understand participant experience of accessing an adapted programme via videoconference.
Participants: Adults with obesity (BMI ≥ 35kg/m ), referred to an NHS Dietetics service in Wales, were offered a group videoconference weight management programme as an optional alternative to in-person groups.
The Electron Loss and Fields Investigation with a Spatio-Temporal Ambiguity-Resolving option (ELFIN-STAR, or heretoforth simply: ELFIN) mission comprises two identical 3-Unit (3U) CubeSats on a polar (∼93 inclination), nearly circular, low-Earth (∼450 km altitude) orbit. Launched on September 15, 2018, ELFIN is expected to have a >2.5 year lifetime.
View Article and Find Full Text PDFUnderstanding the effect of chemical composition on the strength of magnetic interactions is key to the design of magnets with high operating temperatures. The magnetic divalent first-row transition metal (TM) thiocyanates are a class of chemically simple layered molecular frameworks. Here, we report two new members of the family, manganese(II) thiocyanate, Mn(NCS), and iron(II) thiocyanate, Fe(NCS).
View Article and Find Full Text PDFDefect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the subnanometer imaging used to observe individual defects.
View Article and Find Full Text PDFWe report the structures of six new divalent transition metal hexathiocyanatobismuthate frameworks with the generic formula , M = Mn, Co, Ni and Zn. These frameworks are defective analogues of the perovskite-derived trivalent transition metal hexathiocyanatobismuthates M[Bi(SCN)]. The defects in these new thiocyanate frameworks order and produce complex superstructures due to the low symmetry of the parent structure, in contrast to the related and more well-studied cyanide Prussian Blue analogues.
View Article and Find Full Text PDFWe present an open-source program free to download for academic use with a full user-friendly graphical interface for performing flexible and robust background subtraction and dipole fitting on magnetization data. For magnetic samples with small moment sizes or sample environments with large or asymmetric magnetic backgrounds, it can become necessary to separate background and sample contributions to each measured raw voltage measurement before fitting the dipole signal to extract magnetic moments. Originally designed for use with pressure cells on a Quantum Design MPMS3 SQUID magnetometer, SquidLab is a modular object-oriented platform implemented in Matlab with a range of importers for different widely available magnetometer systems (including MPMS, MPMS-XL, MPMS-IQuantum, MPMS3, and S700X models) and has been tested with a broad variety of background and signal types.
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