(RPhP)[Mn(dca)]: A Family of Glass-Forming Hybrid Organic-Inorganic Materials.

ABX-type hybrid organic-inorganic structures have recently emerged as a new class of meltable materials. Here, by the use of phenylphosphonium derivatives as A cation, we study liquid- and glass-forming behavior of a new family of hybrid structures, (RPhP)[Mn(dca)] (R = Me, Et, Ph; dca = dicyanamide). These new compounds melt at 196-237 °C () and then vitrify upon cooling to room temperature, forming glasses.

High ammonia adsorption in copper-carboxylate materials: host-guest interactions and crystalline-amorphous-crystalline phase transitions.

We report the high NH uptake in a series of copper-carboxylate materials, namely MFM-100, MFM-101, MFM-102, MFM-126, MFM-127, MFM-190(F), MFM-170, and Cu-MOP-1a. At 273 K and 1 bar, MFM-101 shows an exceptional uptake of 21.9 mmol g.

Structural Evolution in Disordered Rock Salt Cathodes.

Li-excess Mn-based disordered rock salt oxides (DRX) are promising Li-ion cathode materials owing to their cost-effectiveness and high theoretical capacities. It has recently been shown that Mn-rich DRX LiMnMO ( ≥ 0.5, M are hypervalent ions such as Ti and Nb) exhibit a gradual capacity increase during the first few charge-discharge cycles, which coincides with the emergence of spinel-like domains within the long-range DRX structure coined as "δ phase".

Observation of a Reversible Order-Order Transition in a Metal-Organic Framework - Ionic Liquid Nanocomposite Phase-Change Material.

Metal-organic framework (MOF) composite materials containing ionic liquids (ILs) have been proposed for a range of potential applications, including gas separation, ion conduction, and hybrid glass formation. Here, an order transition in an IL@MOF composite is discovered using CuBTC (copper benzene-1,3,5-tricarboxylate) and [EMIM][TFSI] (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide). This transition - absent for the bare MOF or IL - provides an extended super-cooling range and latent heat at a capacity similar to that of soft paraffins, in the temperature range of ≈220 °C.

Seeing the Unseen: The Structural Influence of the Lone Pair Electrons in PbWO.

Pair distribution function (PDF) analysis of the scheelite-type material PbWO reveals previously unidentified short-range structural distortions in the PbO polyhedra and WO tetrahedra not observed in the similarly structured CaWO. These local distortions are a result of the structural influence of the Pb 6s lone pair electrons. These are not evident from the Rietveld analysis of synchrotron X-ray or neutron powder diffraction data, nor do they strongly influence the X-ray PDF (XPDF).

Tetrahedra Rotational and Displacive Disorder in the Scheelite-Type Oxide CsReO.

Scheelite-type metal oxides are a notable class of functional materials, with applications including ionic conductivity, photocatalysis, and the safe storage of radioactive waste. To further engineer these materials for specific applications, a detailed understanding of how their properties can change under different conditions is required─not just in the long-range average structure but also in the short-range local structure. This paper outlines a detailed investigation of the metal oxide CsReO, which exhibits an uncommon orthorhombic pseudo-scheelite-type structure at room temperature.

Intercalated Water Drives Anomalous Thermal Expansion in the Tetragonal Zircon Structured Bismuth Vanadate BiVO Photocatalyst.

The thermal transformation of the tetragonal-zircon (tz-) to tetragonal-scheelite (ts-)BiVO was studied by in situ synchrotron X-ray diffraction, thermogravimetric analysis, and Fourier-transformed infrared spectroscopy. Upon heating, the tetragonal zircon polymorph of BiVO (tz-BiVO) transitioned to the ts-polymorph between 693-773 K. Above 773 K, single phase ts-BiVO was observed before transitioning to the monoclinic fergusonite (mf-) polymorph upon cooling.

Local Order in Liquid Gallium-Indium Alloys.

Liquid metals such as eutectic Ga-In alloys have low melting points and low toxicity and are used in catalysis and micro-robotics. This study investigates the local atomic structure of liquid gallium-indium alloys by a combination of density measurements, diffraction data, and Monte-Carlo simulation via the empirical potential structure refinement approach. A high- shoulder observed in liquid Ga is related to structural rearrangements in the second coordination shell.

Noncovalent bonding assessment by pair distribution function.

Noncovalent interactions are essential in the formation and properties of a diverse range of materials. However, reliably identifying noncovalent interactions remains challenging using conventional methods such as X-ray diffraction, especially in nanocrystalline, poorly crystalline or amorphous materials which lack long-range lattice periodicity. Here, we demonstrate the accurate determination of deviations in the local structure and tilting of aromatic rings during the temperature-induced first order structural transition in the 1 : 1 adduct of 4,4'-bipyridinium squarate (BIPY:SQA) from the low temperature form HAZFAP01 to high temperature HAZFAP07 by X-ray pair distribution function.

Formation of a meltable purinate metal-organic framework and its glass analogue.

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.

Tetrahedral Displacive Disorder in the Scheelite-Type Oxide RbReO.

Oxides exhibiting the scheelite-type structure are an important class of functional materials with notable applications in photocatalysis, luminescence, and ionic conductivity. Like all materials, understanding their atomic structure is fundamental to engineering their physical properties. This study outlines a detailed structural investigation of the scheelite-type oxide RbReO, which exhibits a rare long-range phase transition from 4/ to 4/ upon heating.

Multivariate analysis of disorder in metal-organic frameworks.

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.

Principles of melting in hybrid organic-inorganic perovskite and polymorphic ABX structures.

Four novel dicyanamide-containing hybrid organic-inorganic ABX structures are reported, and the thermal behaviour of a series of nine perovskite and non-perovskite [AB(N(CN))] (A = (CH)N, (CH)N, (CH)N; B = Co, Fe, Mn) is analyzed. 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 (CH)N → (CH)N → (CH)N was observed to result in a decrease in through an increase in Δ .

Correlating Local Structure and Sodium Storage in Hard Carbon Anodes: Insights from Pair Distribution Function Analysis and Solid-State NMR.

Hard carbons are the leading candidate anode materials for sodium-ion batteries. However, the sodium-insertion mechanisms remain under debate. Here, employing a novel analysis of operando and ex situ pair distribution function (PDF) analysis of total scattering data, supplemented by information on the local electronic structure provided by operando Na solid-state NMR, we identify the local atomic environments of sodium stored within hard carbon and provide a revised mechanism for sodium storage.

Frustrated flexibility in metal-organic frameworks.

Stimuli-responsive flexible metal-organic frameworks (MOFs) remain at the forefront of porous materials research due to their enormous potential for various technological applications. Here, we introduce the concept of frustrated flexibility in MOFs, which arises from an incompatibility of intra-framework dispersion forces with the geometrical constraints of the inorganic building units. Controlled by appropriate linker functionalization with dispersion energy donating alkoxy groups, this approach results in a series of MOFs exhibiting a new type of guest- and temperature-responsive structural flexibility characterized by reversible loss and recovery of crystalline order under full retention of framework connectivity and topology.

Stepwise collapse of a giant pore metal-organic framework.

Defect engineering is a powerful tool that can be used to tailor the properties of metal-organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal-linker bonds, generating additional coordinatively unsaturated metal sites, and ultimately causes amorphisation.

Mixed hierarchical local structure in a disordered metal-organic framework.

Amorphous metal-organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe-BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood.

Non-equilibrium metal oxides via reconversion chemistry in lithium-ion batteries.

Binary metal oxides are attractive anode materials for lithium-ion batteries. Despite sustained effort into nanomaterials synthesis and understanding the initial discharge mechanism, the fundamental chemistry underpinning the charge and subsequent cycles-thus the reversible capacity-remains poorly understood. Here, we use in operando X-ray pair distribution function analysis combining with our recently developed analytical approach employing Metropolis Monte Carlo simulations and non-negative matrix factorisation to study the charge reaction thermodynamics of a series of Fe- and Mn-oxides.

Correction: X-ray pair distribution function analysis and electrical and electrochemical properties of cerium doped LiLaNbO garnet solid-state electrolyte.

Correction for 'X-ray pair distribution function analysis and electrical and electrochemical properties of cerium doped Li5La3Nb2O12 garnet solid-state electrolyte' by Bo Dong et al., Dalton Trans., 2020, 49, 11727-11735, DOI: 10.

X-ray pair distribution function analysis and electrical and electrochemical properties of cerium doped LiLaNbO garnet solid-state electrolyte.

Garnet solid state electrolytes have been considered as potential candidates to enable next generation all solid state batteries (ASSBs). To facilitate the practical application of ASSBs, a high room temperature ionic conductivity and a low interfacial resistance between solid state electrolyte and electrodes are essential. In this work, we report a study of cerium doped Li5La3Nb2O12 through X-ray pair distribution function analysis, impedance spectroscopy and electrochemical testing.

Temperature reversible synergistic formation of cerium oxyhydride and Au hydride: a combined XAS and XPDF study.

In situ studies on the physical and chemical properties of Au in inverse ceria alumina supported catalysts have been conducted between 295 and 623 K using high energy resolved fluorescence detection X-ray absorption near edge spectroscopy and X-ray total scattering. Precise structural information is extracted on the metallic Au phase present in a 0.85 wt% Au containing inverse ceria alumina catalyst (ceria/Au/alumina).

Halogenated Metal-Organic Framework Glasses and Liquids.

The synthesis of four novel crystalline zeolitic imidazolate framework (ZIF) structures using a mixed-ligand approach is reported. The inclusion of both imidazolate and halogenated benzimidazolate-derived linkers leads to glass-forming behavior by all four structures. Melting temperatures are observed to depend on both electronic and steric effects.

Average and Local Structure of Apatite-Type Germanates and Implications for Oxide Ion Conductivity.

Materials with the apatite structure have a range of important applications in which their function is influenced by details of their local structure. Here, we describe an average and local structural study to probe the origins of high-temperature oxide ion mobility in La(GeO)O and LaBi(GeO)O oxygen-excess materials, using the low-conductivity interstitial oxide-free LaSr(GeO)O as a benchmark. For La and LaBi, we locate the interstitial oxygen, O, responsible for conductivity by Rietveld refinement and relate the 6/ to 1̅ phase transitions on cooling to oxygen ordering.

Synthesis and Properties of a Compositional Series of MIL-53(Al) Metal-Organic Framework Crystal-Glass Composites.

Metal-organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room-temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy.