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The temperature-induced depolarisation of (100-x-y)Na0.5Bi0.5TiO3-xBaTiO3-yK0.5Na0.5NbO3 ceramics has been investigated using polarisation-electric field (P-E) loops, current density-electric field loops, dielectric measurements, thermally stimulated depolarisation current measurements, and x-ray diffraction. The depolarisation temperature (Td) values were measured using the thermally stimulated depolarisation current on each furnace to allow the comparison of results between techniques. Td closely agreed with the values determined from the dielectric anomalies resulting from the ferroelectric to relaxor transition (TF-R). Tddetermined using pinching of P-E loops was 2-9K higher, and as the maximum applied electric field was increased, the value of Td increased. The pinching of the loop was shown not to be from an antiferroelectric structure; pinching occurs as the induced ferroelectric phase becomes unstable and returns to its unpoled relaxor state. This is the tuning of the transition from the poled non-ergodic state to the ergodic relaxor state with the applied electric field. Above Td, the P-E loops return to a relaxor state before a reverse field is applied, giving the appearance of a classic antiferroelectric P-E loop. [ABSTRACT FROM AUTHOR]

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points. [ABSTRACT FROM AUTHOR]

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points. [ABSTRACT FROM AUTHOR]

The symmetry of the intermediate high-temperature phase of PbHfO3 has been determined unambiguously to be orthorhombic using a combination of high-resolution X-ray diffraction and birefringence imaging microscopy measurements of crystal plates. While lattice parameter measurements as a function of temperature in the intermediate phase are consistent with either orthorhombic or tetragonal symmetry, domain orientations observed in birefringence imaging microscopy measurements utilizing the Metripol system are only consistent with orthorhombic symmetry with the unit cell in the rhombic orientation of the pseudocubic unit cell. [ABSTRACT FROM AUTHOR]

A study of vapour transport equilibrated crystals of LiTaO3 shows periodic fringes that change with temperature. The origin of these fringes and their behaviour is explained in terms of domains with slanted walls. Micro-Raman measurements have been used to determine the Li2O concentration through the crystals, and by comparison with the observed fringe pattern the variation of birefringence with Li2O content has been determined. [ABSTRACT FROM AUTHOR]

The article discusses a birefringence imaging microscopic study of LiTaO3 and LiTaxNb1-xO3 crystals with near-zero birefringence at room temperature. It revealed that periodic self-organized birefringent stripes often formed in directions consistent with the type of cleavage planes in both types of crystal. It also showed that a microscopic strain influences the stabilization of the periodicity of these stripes.

An optimised synthesis of the metal-organic framework (MOF) UiO-66(Ce) is reported using a modulator-free route, yielding ~5 g of material with high crystallinity and 22 % ligand defect. Two methods are developed for loading gold nanoparticles onto the MOF. The first uses a double-solvent method to introduce HAuCl 4 onto UiO-66(Ce), followed by reduction under 5 % H 2 in N 2 , while the second is a novel one-pot method where HAuCl 4 is added to the synthesis mixture, forming Au nanoparticles within the pores of the UiO-66(Ce) during crystallisation. Analysis using powder X-ray diffraction (PXRD), nitrogen adsorption isotherms, transmission electron microscopy and small-angle X-ray scattering (SAXS) reveals that the two-step double-solvent method yields gold crystallites on the external surface of the MOF particles that are visible by PXRD. In contrast, the one-pot method forms smaller gold crystallites, with a distribution of sizes centred on ~4 nm diameter as seen by SAXS, with evidence from PXRD for the smallest particles being present within the MOF structure. The Au-loaded UiO-66(Ce) materials are evaluated for the catalytic oxidation of vanillyl alcohol to vanillin at 60 °C. Our findings indicate that incorporating Au nanoparticles via the one-pot synthesis method, enhances redox activity, achieving 43 % conversion and 90 % selectivity towards vanillin., (© 2024 The Authors. Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

Prussian blue is known for its high affinity for thallium and other univalent metal cations and has been used as a treatment for radiocaesium and thallium/radiothallium poisoning. While Prussian blue nanoparticles (PBNPs) show potential for binding radioactive thallium for further use in nuclear medicine applications, the inclusion mechanism remains elusive. Understanding the interaction between PBNPs and 201 Tl is essential for identifying the physicochemical and radiochemical properties required for optimal in vivo performance. In this work, we evaluated the binding mechanism between Tl and PBNPs with different coatings and core shapes. Combining PBNPs with [ 201 Tl] thallium(I) chloride provided high radiolabelling yields and radiochemical stabilities under physiological conditions. Comprehensive characterisation by different X-ray techniques confirmed that Tl ions are located in the interstitial sites within the crystal structure, maintaining the integrity of the iron (Fe) 4p electronic distribution and inducing local modifications in the nearby C-N ligands. Additionally, this inclusion does not impact the core or the shell of the nanoparticles but does alter their ionic composition. The PB ionic network undergoes significant changes, with a substantial drop in K + content, confirming that Tl + ions replace K + and occupy additional spaces within the crystal structure. These results open new opportunities in nuclear medicine applications with 201 Tl-PBNPs where the size, shape and composition of the particles can be specifically tuned depending on the desired biological properties without affecting the radiochemical performance as a vehicle for 201 Tl.

Control of phase separation of VO 4 3- and rare earth precursors in reverse microemulsions afforded ∼35 nm YVO 4 nanoparticles with functionalisable ∼7 ± 3 nm nanopores. Doping by Eu 3+ allowed luminescent probing of interfacial crystallisation while xylenol orange absorption showed molecular encapsulation in particle cavities. This provides potential multifunctional systems combining UV-Vis-NIR luminescence and (photo)active molecules for optical sensing.

An effective approach is reported to enhance the stability of inverted organo-tin halide perovskite photovoltaics based on capping the cathode with a thin layer of bismuth. Using this simple approach, unencapsulated devices retain up to 70% of their peak power conversion efficiency after up to 100 h testing under continuous one sun solar illumination in ambient air and under electrical load, which is exceptional stability for an unencapsulated organo-tin halide perovskite photovoltaic device tested in ambient air. The bismuth capping layer is shown to have two functions: First, it blocks corrosion of the metal cathode by iodine gas formed when those parts of the perovskite layer not protected by the cathode degrade. Second, it sequesters iodine gas by seeding its deposition on top of the bismuth capping layer, thereby keeping it away from the electro-active parts of the device. The high affinity of iodine for bismuth is shown to correlate with the high polarizability of bismuth and the prevalence of the (012) crystal face at its surface. Bismuth is ideal for this purpose, because it is environmentally benign, non-toxic, stable, cheap, and can be deposited by simple thermal evaporation at low temperature immediately after deposition of the cathode., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Atherosclerosis is often described as a single disease entity; however, the morphology of each plaque is unique to the individual. The field currently lacks a technique that can discriminate stable from unstable plaques, to identify those at risk of a thromboembolic event. Small- and wide-angle X-ray scattering (SAXS/WAXS) holds the potential to be able to identify key materials present in a plaque, such as cholesterol species, collagen, low-density lipoproteins (LDLs), and hydroxyapatite. Protocols have been established for the preparation of excised human atherosclerotic tissue that are investigated herein. This includes the fixing, sectioning, and substrate selection of the sample. Through several sample preparation methods, vast improvements have been made to sample-to-noise ratio and background subtraction., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

We report the polymerisation-induced self-assembly of poly(lauryl methacrylate)-graft-poly(benzyl methacrylate) copolymers during reversible addition-fragmentation chain transfer (RAFT) grafting from polymerisation in a backbone-selective solvent. Electron microscopy images suggest the phase separation of grafts to result in a network of spherical particles, due to the ability of the branched architecture to freeze chain entanglements and to bridge core domains. Small-angle X-ray scattering data suggest the architecture promotes the formation of multicore micelles, the core morphology of which transitions from spheres to worms, vesicles, and inverted micelles with increasing volume fraction of the grafts. A time-resolved SAXS study is presented to illustrate the formation of the inverted phase during a polymerisation. The grafted architecture gives access to unusual morphologies and provides exciting new handles for controlling the polymer structure and material properties., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The composition of atmospheric aerosols varies with time, season, location, and environment. This affects key aerosol properties such as hygroscopicity and reactivity, influencing the aerosol's impact on the climate and air quality. The organic fraction of atmospheric aerosol emissions often contains surfactant material, such as fatty acids. These molecules are known to form three-dimensional nanostructures in contact with water. Different nanostructures have marked differences in viscosity and diffusivity that are properties whose understanding is essential when considering an aerosol's atmospheric impact. We have explored a range of nanostructures accessible to the organic surfactant oleic acid (commonly found in cooking emissions), simulating variation that is likely to happen in the atmosphere. This was achieved by changing the amount of water, aqueous phase salinity and by addition of other commonly coemitted compounds: sugars and stearic acid (the saturated analogue of oleic acid). The nanostructure was observed by both synchrotron and laboratory small/wide angle X-ray scattering (SAXS/WAXS) and found to be sensitive to the proxy composition. Additionally, the spacing between repeat units in these nanostructures was water content dependent (i.e., an increase from 41 to 54 Å in inverse hexagonal phase d -spacing when increasing the water content from 30 to 50 wt %), suggesting incorporation of water within the nanostructure. A significant decrease in mixture viscosity was also observed with increasing water content from ∼10 4 to ∼10 2 Pa s when increasing the water content from 30 to 60 wt %. Time-resolved SAXS experiments on levitated droplets of this proxy confirm the phase changes observed in bulk phase mixtures and demonstrate that coexistent nanostructures can form in droplets. Aerosol compositional and subsequent nanostructural changes could affect aerosol processes, leading to an impact on the climate and urban air pollution.

The air tolerant precatalyst, [Rh(L)(NBD)]Cl ( [1]Cl ) [L = κ 3 -( i Pr 2 PCH 2 CH 2 ) 2 NH, NBD = norbornadiene], mediates the selective synthesis of N -methylpolyaminoborane, (H 2 BNMeH) n , by dehydropolymerization of H 3 B·NMeH 2 . Kinetic, speciation, and DFT studies show an induction period in which the active catalyst, Rh(L)H 3 ( 3 ), forms, which sits as an outer-sphere adduct 3·H 3 BNMeH 2 as the resting state. At the end of catalysis, dormant Rh(L)H 2 Cl ( 2 ) is formed. Reaction of 2 with H 3 B·NMeH 2 returns 3 , alongside the proposed formation of boronium [H 2 B(NMeH 2 ) 2 ]Cl. Aided by isotopic labeling, Eyring analysis, and DFT calculations, a mechanism is proposed in which the cooperative "PNHP" ligand templates dehydrogenation, releasing H 2 B═NMeH (Δ G ‡ calc = 19.6 kcal mol -1 ). H 2 B═NMeH is proposed to undergo rapid, low barrier, head-to-tail chain propagation for which 3 is the catalyst/initiator. A high molecular weight polymer is formed that is relatively insensitive to catalyst loading ( M n ∼71 000 g mol -1 ; Đ , of ∼ 1.6). The molecular weight can be controlled using [H 2 B(NMe 2 H) 2 ]Cl as a chain transfer agent, M n = 37 900-78 100 g mol -1 . This polymerization is suggested to arise from an ensemble of processes (catalyst speciation, dehydrogenation, propagation, chain transfer) that are geared around the concentration of H 3 B·NMeH 2 . TGA and DSC thermal analysis of polymer produced on scale (10 g, 0.01 mol % [1]Cl ) show a processing window that allows for melt extrusion of polyaminoborane strands, as well as hot pressing, drop casting, and electrospray deposition. By variation of conditions in the latter, smooth or porous microstructured films or spherical polyaminoboranes beads (∼100 nm) result.

We show that particle size, morphology, nanocrystallinity, surface area, and defect density of (Y,Eu)VO 4 structures can be tuned by one-pot colloidal conversion of rare earth hydroxycarbonates in water/ethylene glycol (EG) suspensions. Using small angle X-ray scattering, transmission electron microscopy and dynamic light scattering, we show how volume fractions of EG direct the amorphous to crystalline conversion at 1 atm/95 °C by controlling size and aggregation of hydroxycarbonate precursors. A template effect due to a Kirkendall-type conversion occurs for low EG contents, yielding solids with high densities of oxygen defects, as demonstrated by O 2 uptakes in thermogravimetry and X-ray photoelectron spectroscopy profiles. Starting from small and aggregated hydroxycarbonates high-porosity (Y,Eu)VO 4 nanoparticles were produced with expanded unit cells and short-range (<100 Å) crystalline ordering. We explored the effects of synthesis on the textural, microstructure, and defects of (Y,Eu)VO 4 solids, which were further correlated to the spectroscopic profiles of Eu 3+ -activated samples. We show that the ratios between Eu 3+ 5 D 0 internal quantum yields and particle diameters can be directly correlated to the particle surface areas, opening new perspectives for theoretical detailing of f-f luminescence in YVO 4 solids, and enabling accurate tuning of structure and applicability of colloidal vanadate nanoparticles for sensing and catalysis applications.

The structure and molecular order in the thermotropic ionic liquid crystal (ILC), [choline][geranate(H)octanoate], an analogue of Choline And GEranate (CAGE), which has potential for use as a broad-spectrum antimicrobial and transdermal and oral delivery agent, were investigated by magic-angle spinning (MAS) nuclear magnetic resonance (NMR), polarizing optical microscopy, small-angle X-ray scattering (SAXS), and mass spectrometry. Mass spectrometry and the 1 H NMR chemical shift reveal that CAGE-oct is a dynamic system, with metathesis (the exchange of interacting ions) and hydrogen exchange occurring between hydrogen-bonded/ionic complexes such as [(choline)(geranate)(H)(octanoate)], [(choline)(octanoate) 2 (H)], and [(choline)(geranate) 2 (H)]. These clusters, which are shown by mass spectrometry to be significantly more stable than expected for typical electrostatic ion clusters, involve hydrogen bonding between the carboxylic acid, carboxylate, and hydroxyl groups, with rapid hydrogen bond breaking and re-formation observed to average the 1 H chemical shifts. The formation of a partial bilayer liquid crystal (LC) phase was identified by SAXS and polarizing optical microscopy at temperatures below ∼293 K. The occurrence of this transition close to room temperature could be utilized as a potential temperature-induced "switch" of the anisotropic properties for particular applications. The presence of an isotropic component of approximately 23% was observed to coexist with the LC phase, as detected by polarizing optical microscopy and quantified by both 1 H- 13 C dipolar-chemical shift correlation (DIPSHIFT) and 1 H double-quantum (DQ) MAS NMR experiments. At temperatures above the LC-to-isotropic transition, intermediate-range order (clustering of polar and nonpolar domains), a feature of many ILs, persists. Site-specific order parameters for the LC phase of CAGE-oct were obtained from the MAS NMR measurement of the partially averaged 13 C- 1 H dipolar couplings ( D CH ) by cross-polarization (CP) build-up curves and DIPSHIFT experiments, and 1 H- 1 H dipolar couplings ( D HH ) by double-quantum (DQ) build-up curves. The corresponding order parameters, S CH and S HH , are in the range 0-0.2 and are lower compared to those for smectic (i.e., layered) phases of conventional nonionic liquid crystals, resembling those of lamellar phases formed by lyotropic surfactant-solvent systems.