Origin of Polarization in Bismuth Sodium Titanate-Based Ceramics.

The classical view of the structural changes that occur at the ferroelectric transition in perovskite-structured systems, such as BaTiO, is that polarization occurs due to the off-center displacement of the B-site cations. Here, we show that in the bismuth sodium titanate (BNT)-based composition 0.2(BaSrTiO)-0.

Structure-Property Relationships for the Electronic Applications of Bis-Adduct Isomers of Phenyl-C Butyric Acid Methyl Ester.

Higher adducts of a fullerene, such as the bis-adduct of PCBM (bis-PCBM), can be used to achieve shallower molecular orbital energy levels than, for example, PCBM or C Substituting the bis-adduct for the parent fullerene is useful to increase the open-circuit voltage of organic solar cells or achieve better energy alignment as electron transport layers in, for example, perovskite solar cells. However, bis-PCBM is usually synthesized as a mixture of structural isomers, which can lead to both energetic and morphological disorder, negatively affecting device performance. Here, we present a comprehensive study on the molecular properties of 19 pure bis-isomers of PCBM using a variety of characterization methods, including ultraviolet photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, single crystal structure, and (time-dependent) density functional theory calculation.

Pillared Vanadium Molybdenum Disulfide Nanosheets: Toward High-Performance Cathodes for Magnesium-Ion Batteries.

If magnesium-ion batteries (MIBs) are to be seriously considered for next-generation energy storage, then a number of major obstacles need to be overcome. The lack of reversible cathode materials with sufficient capacity and cycle life is one of these challenges. Here, we report a new MIB cathode constructed of vertically stacked vanadium molybdenum sulfide (VMS) nanosheets toward addressing this challenge.

Structure and Conductivity in LISICON Analogues within the LiGeO-LiMoO System.

New solid electrolytes are crucial for the development of all-solid-state lithium batteries with advantages in safety and energy densities over current liquid electrolyte systems. While some of the best solid-state Li-ion conductors are based on sulfides, their air sensitivity makes them less commercially attractive, and attention is refocusing on air-stable oxide-based systems. Among these, the LISICON-structured systems, such as LiZnGeO and LiVGeO, have been relatively well studied.

Highly porous phosphate-based glasses for controlled delivery of antibacterial Cu ions prepared sol-gel chemistry.

Mesoporous glasses are a promising class of bioresorbable biomaterials characterized by high surface area and extended porosity in the range of 2 to 50 nm. These peculiar properties make them ideal materials for the controlled release of therapeutic ions and molecules. Whilst mesoporous silicate-based glasses (MSG) have been widely investigated, much less work has been done on mesoporous phosphate-based glasses (MPG).

Local Structure in α-BIMEVOXes (ME = Ge, Sn).

The BIMEVOXes are among the best oxide ion conductors at low and intermediate temperatures. Their high conductivity is associated with local defect structure. In this work, the local structures of two BIMEVOX compositions, BiVGeO and BiVSnO, are examined using total neutron and X-ray scattering methods, with both compositions exhibiting the ordered α-phase at 25 °C and the disordered γ-phase at 700 °C.

Antiferroelectric-like Behavior in a Lead-Free Perovskite Layered Structure Ceramic.

Antiferroelectric (AFE) materials have been intensively studied due to their potential uses in energy storage applications and energy conversion. These materials are characterized by double polarization-electric field (-) hysteresis loops and nonpolar crystal structures. Unusually, in the present work, SrLaTaTiO (STLT32), SrLaTaTiO (STLT36), and SrCaTaO (SCT15), lead-free perovskite layered structure (PLS) materials, are shown to exhibit AFE-like double - hysteresis loops despite maintaining a polar crystal structure.

Phyto-inspired Cu/Bi oxide-based nanocomposites: synthesis, characterization, and energy relevant investigation.

A modified and sustainable approach is reported in this research for the synthesis of a spherical-shaped CuO-BiO electrode material for electrochemical studies. Aqueous extract derived from the plant L. (Amaranthaceae) (AVL) was used as a reducing agent for morphological control of the synthesis of CuO-BiO nanocomposites.

Grain Size Effects in Mn-Modified 0.67BiFeO-0.33BaTiO Ceramics.

Grain size can have significant effects on the properties of electroceramics for dielectric, piezoelectric, and ferroelectric applications. Here, we systematically investigate the effect of grain size on the structure and properties of Mn-modified 0.67BiFeO-0.

Structural Evolution in BiNbO.

The sequence of transitions between different phases of BiNbO has been thoroughly investigated and clarified using thermal analysis, high-resolution neutron diffraction, and Raman spectroscopy. The theoretical optical phonon modes of the α-phase have been calculated. Based on thermoanalytical data supported by density functional theory (DFT) calculations, the β-phase is proposed to be metastable, while the α- and γ-phases are stable below and above 1040 °C, respectively.

Effect of substituting non-polar chains with polar chains on the structural dynamics of small organic molecule and polymer semiconductors.

The processability and optoelectronic properties of organic semiconductors can be tuned and manipulated via chemical design. The substitution of the popular alkyl side chains by oligoethers has recently been successful for applications such as bioelectronic sensors and photocatalytic hydrogen evolution. Beyond the differences in polarity, the carbon-oxygen bond in oligoethers is likely to render the system softer and more prone to dynamical disorder that can be detrimental to charge transport for example.

Terahertz Reading of Ferroelectric Domain Wall Dielectric Switching.

Ferroelectric domain walls (DWs) are important nanoscale interfaces between two domains. It is widely accepted that ferroelectric domain walls work idly at terahertz (THz) frequencies, consequently discouraging efforts to engineer the domain walls to create new applications that utilize THz radiation. However, the present work clearly demonstrates the activity of domain walls at THz frequencies in a lead-free Aurivillius phase ferroelectric ceramic, CaRbCeBiNbO, examined using THz-time-domain spectroscopy (THz-TDS).

Mesoporous Phosphate-Based Glasses Prepared via Sol-Gel.

In the present study, a mesoporous phosphate-based glass (MPG) in the PO-CaO-NaO system was synthesized, for the first time, using a combination of sol-gel chemistry and supramolecular templating. A comparison between the structural properties, bioactivity, and biocompatibility of the MPG with a non-porous phosphate-based glass (PG) of analogous composition prepared via the same sol-gel synthesis method but in the absence of a templating surfactant is also presented. Results indicate that the MPG has enhanced bioactivity and biocompatibility compared to the PG, despite having a similar local structure and dissolution properties.

Determining phase transitions of layered oxides via electrochemical and crystallographic analysis.

The chemical diffusion coefficient in LiNiMnCoO was determined via the galvanostatic intermittent titration technique in the voltage range 3 to 4.2 V. Calculated diffusion coefficients in these layered oxide cathodes during charging and discharging reach a minimum at the open-circuit voltage of 3.

Solution-Processed Epitaxial Growth of Arbitrary Surface Nanopatterns on Hybrid Perovskite Monocrystalline Thin Films.

Semiconductor surface patterning at the nanometer scale is crucial for high-performance optical, electronic, and photovoltaic devices. To date, surface nanostructures on organic-inorganic single-crystal perovskites have been achieved mainly through destructive methods such as electron-beam lithography and focused ion beam milling. Here, we present a solution-based epitaxial growth method for creating nanopatterns on the surface of perovskite monocrystalline thin films.

Conformational Analysis of [60]PCBM via Second-Order Proton NMR Spin-Spin Coupling Effects.

The H NMR spectrum of phenyl C butyric acid methyl ester ([60]PCBM) was recorded at high resolution (600 MHz). All of the H resonances expected of the -symmetric molecule were observed. The spin-spin couplings in the H NMR spectrum were not as expected at first order.

Mesoporous Strontium-Doped Phosphate-Based Sol-Gel Glasses for Biomedical Applications.

Mesoporous phosphate-based glasses have great potential as biomedical materials being able to simultaneously induce tissue regeneration and controlled release of therapeutic molecules. In the present study, a series of mesoporous phosphate-based glasses in the PO-CaO-NaO system, doped with 1, 3, and 5 mol% of Sr, were prepared using the sol-gel method combined with supramolecular templating. A sample without strontium addition was prepared for comparison.

Preparation of an Anti-Aggregation Silica/Zinc/Graphene Oxide Nanocomposite with Enhanced Adsorption Capacity.

Nanomaterials play a significant role in adsorption treatment of dye wastewater, but irreversible aggregation of nanoparticles poses a significant problem. In this work, nanomesoporous zinc-doped silicate (NMSZ) was prepared by an in situ method. To prevent agglomeration, NMSZ was covalently bonded to graphene oxide (GO) sheets to form a nano-silica/zinc/graphene oxide composite (GO-NMSZ), aimed at removal of cationic dye methylene blue (MB).

Defect structure in δ-BiPbYO.

A detailed study of the defect structure in a di-substituted δ-BiO type phase, δ-BiPbYO, is presented. Using a combination of conventional Rietveld analysis of neutron diffraction data, reverse Monte Carlo (RMC) analysis of total neutron scattering data and molecular dynamics (MD) simulations, both average and local structures have been characterized. δ-BiPbYO represents a model system for the highly conducting δ-BiO type phases, in which there is a higher nominal vacancy concentration than in the unsubstituted parent compound.

Structural Identification of 19 Purified Isomers of the OPV Acceptor Material bisPCBM by C NMR and UV-Vis Absorption Spectroscopy and High-Performance Liquid Chromatography.

The molecular structures of 19 purified isomers of bis-phenyl-C-butyric acid methyl ester were identified by a combination of C NMR and UV-vis absorption spectroscopies and high-performance liquid chromatography (HPLC) retention time analysis. All 19 isomers are dicyclopropafullerenes (none are homofullerenes). There were seven isomers with C molecular point-group symmetry, four with C , six with C, one with C, and one with C symmetry.

The role of aluminium and silicon in the setting chemistry of glass ionomer cements.

A model of the setting chemistry of glass-ionomer cements (GICs) is proposed based on 27Al and 29Si solid state nuclear magnetic resonance spectroscopy data on three GICs. All the precursor glasses are found to contain three aluminium species viz.: four, five and six-coordinate aluminium environments as well as four-bridging silicate tetrahedra.

Quenching of IR luminescence of erbium, neodymium, and ytterbium beta-diketonate complexes by ligand C-H and C-D bonds.

The effect of CH and CD quenching on the luminescence lifetime of Er(3+) Nd(3+) and Yb(3+) in the Cs[Ln(HFA)(4)] system has been quantified, and we have shown that for Er(3+) ions the quenching is dominated by the nearest neighbor CH oscillators, whereas for Nd(3+) ions the roles of more distant CH oscillators and nearest neighbor CD oscillators are important.

Neutron and electron diffraction studies of La(Zn1/2Ti1/2)O3 perovskite.

The crystallography and microwave dielectric properties of La(Zn(1/2)Ti(1/2))O(3) (LZT) ceramics prepared via the mixed-oxide route were investigated in this study. While samples were largely single phase, small amounts of ZnO impurity were detected in sintered pellets. Observed reflections in electron and neutron diffraction patterns indicate that the symmetry of LZT is P2(1)/n.

Structural and electrical characterisation of Li(2)O : TiO(2) : SnO(2) : P(2)O(5) electrolyte glass.

Glasses of general formula 50Li(2)O : xSnO(2) : (10 -x)TiO(2) : 40P(2)O(5)(0.0 < or = x < or = 10) were investigated by differential scanning calorimetry, X-ray diffraction and ac impedance, (31)P solid-state NMR and IR spectroscopies. Three isotropic resonances can be identified in the (31)P NMR spectra, which have been assigned to various phosphate species.

Stray-field imaging and multinuclear magnetic resonance spectroscopy studies on the setting of a commercial glass-ionomer cement.

A commercial glass-ionomer (Fuji II) was studied using different NMR techniques. 1H and 19F stray-field imaging (STRAFI) were used to monitor the curing kinetics of the cement and two processes were distinguished: the gelation and maturation phases. Characterization of the aluminium and silicon species present in the glass component and cement was performed by conventional 27Al and 29Si MAS and two-dimensional 27Al triple quantum MAS NMR (MQMAS) techniques.