Computational Insights into Dion-Jacobson Type Oxide Ion Conductors.

Dion-Jacobson type materials have recently emerged as a new structural family of oxide ion conductors, materials important for applications in a variety of electrochemical devices. While some attempts to improve their ionic conductivity have been reported, a detailed understanding of the underlying oxide ion diffusion mechanisms in these materials is still missing. To explore the structure-property relationships leading to the favorable properties, we carried out molecular dynamics simulations of oxide ion diffusion in CsBiTiNbO.

Oxide Ion Conductivity, Proton Conductivity, and Phase Transitions in Perovskite-Derived Ba Sr YGaO 0 ≤ ≤ 3 Materials.

We report the synthesis, structural characterization, and oxide ion and proton conductivities of the perovskite-related Ba Sr YGaO family. Single-phase samples are prepared for 0 ≤ ≤ 3 and show a complex structural evolution from 2/ to 2 space groups with an increase in . For 1.

Oxide Ion and Proton Conductivity in a Family of Highly Oxygen-Deficient Perovskite Derivatives.

Functional oxides showing high ionic conductivity have many important technological applications. We report oxide ion and proton conductivity in a family of perovskite-related compounds of the general formula AOhTdO, where Oh is an octahedrally coordinated metal ion and Td is a tetrahedrally coordinated metal ion. The high tetrahedral content in these ABO compositions relative to that in the perovskite ABO or brownmillerite ABO structures leads to tetrahedra with only three of their four vertices connected in the polyhedral framework, imparting a potential low-energy mechanism for O migration.

Understanding the Correlation between Oxide Ion Mobility and Site Distributions in BaNbWO.

A correlation between oxygen site distributions and ionic conductivity has been established in the recently discovered family of oxide-ion conductors BaO (M = Nb, V, Mo, W). We rationalize this observation on the basis of structural insights gained from the first single-crystal neutron diffraction data collected for a member of this family, BaNbWO, and theoretical considerations of bonding and O site energies.

Brownmillerite-Type SrScGaO Oxide Ion Conductor: Local Structure, Phase Transition, and Dynamics.

Brownmillerite-type SrScGaO has been investigated by a range of experimental X-ray and neutron scattering techniques (diffraction, total scattering, and spectroscopy) and density functional theory calculations in order to characterize its structure and dynamics. The material undergoes a second-order phase transition on heating during which a rearrangement of the (GaO) tetrahedral chains occurs, such that they change from being essentially fully ordered in a polar structure at room temperature to being orientationally disordered above 400 °C. Pair distribution function analysis carried out using neutron total scattering data suggests that GaO tetrahedra remain as fairly rigid units above and below this transition, whereas coordination polyhedra in the (ScO) layers distort more.

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.

Insight into Design of Improved Oxide Ion Conductors: Dynamics and Conduction Mechanisms in the BiVO Solid Electrolyte.

Extensive quasielastic neutron scattering measurements have been used to directly observe oxide ion dynamics on the nanosecond time scale in bismuth vanadate with formula BiVO, which exhibits remarkable oxide ion conductivity at low temperatures. This is the longest time scale neutron scattering study of any fluorite-type solid electrolyte, and it represents only the second case of oxide ion dynamics in any material observed on a nanosecond time scale by quasielastic neutron scattering. Ab initio molecular dynamics simulations reveal two mechanisms that contribute to the oxide ion dynamics in the material: a slower diffusion process through the Bi-O sublattice and a faster process which corresponds to more localized dynamics of the oxide ions within the VO coordination spheres.

Understanding the Behavior of the Above-Room-Temperature Molecular Ferroelectric 5,6-Dichloro-2-methylbenzimidazole Using Symmetry Adapted Distortion Mode Analysis.

The exploitable properties of many functional materials are intimately linked with symmetry-changing phase transitions. These include properties such as ferroelectricity, second harmonic generation, conductivity, magnetism and many others. We describe a new symmetry-inspired method for systematic and exhaustive evaluation of the symmetry changes possible in molecular systems using molecular distortion modes, and how different models can be automatically tested against diffraction data.

Structure and physicochemical characterization of a naproxen-picolinamide cocrystal.

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug with pain- and fever-relieving properties, currently marketed in the sodium salt form to overcome solubility problems; however, alternative solutions for improving its solubility across all pH values are desirable. NPX is suitable for cocrystal formation, with hydrogen-bonding possibilities via the COOH group. The crystal structure is presented of a 1:1 cocrystal of NPX with picolinamide as a coformer [systematic name: (S)-2-(6-methoxynaphthalen-2-yl)propanoic acid-pyridine-2-carboxamide (1/1), CHO·CHNO].

An Exhaustive Symmetry Approach to Structure Determination: Phase Transitions in Bi2Sn2O7.

The exploitable properties of many materials are intimately linked to symmetry-lowering structural phase transitions. We present an automated and exhaustive symmetry-mode method for systematically exploring and solving such structures which will be widely applicable to a range of functional materials. We exemplify the method with an investigation of the Bi2Sn2O7 pyrochlore, which has been shown to undergo transitions from a parent γ cubic phase to β and α structures on cooling.

Na(+) mobility in sodium strontium silicate fast ion conductors.

We present the first direct evidence of Na-ion mobility in sodium strontium silicate fast ion conductors, based on variable temperature (23)Na solid state NMR spectroscopy and spin-lattice relaxation measurements.

Niclosamide methanol solvate and niclosamide hydrate: structure, solvent inclusion mode and implications for properties.

Structural studies have been carried out of two solid forms of niclosamide [5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide, NCL], a widely used anthelmintic drug, namely niclosamide methanol monosolvate, C13H8Cl2N2O4·CH3OH or NCL·MeOH, and niclosamide monohydrate, denoted HA. The structure of the methanol solvate obtained from single-crystal X-ray diffraction is reported for the first time, elucidating the key host-guest hydrogen-bonding interactions which lead to solvate formation. The essentially planar NCL host molecules interact via π-stacking and pack in a herringbone-type arrangement, giving rise to channels along the crystallographic a axis in which the methanol guest molecules are located.

Systematic and controllable negative, zero, and positive thermal expansion in cubic Zr(1-x)Sn(x)Mo2O8.

We describe the synthesis and characterization of a family of materials, Zr1-xSnxMo2O8 (0 < x < 1), whose isotropic thermal expansion coefficient can be systematically varied from negative to zero to positive values. These materials allow tunable expansion in a single phase as opposed to using a composite system. Linear thermal expansion coefficients, αl, ranging from -7.

Giant deuteron migration during the isosymmetric phase transition in deuterated 3,5-pyridinedicarboxylic acid.

Deuterated 3,5-pyridinedicarboxylic acid exhibits reversible temperature-induced deuteron migration of a magnitude unprecedented in this class of compounds. We used a combination of variable-temperature powder and single-crystal neutron diffraction and density functional theory (DFT)-based computational methods to elucidate the origin of this remarkable behaviour. Single-crystal neutron diffraction shows that between 15 and 300 K, the deuteron moves by 0.

Synthesis, structural and spectroscopic characterization, in vitro cytotoxicity and in vivo activity as free radical scavengers of chlorido(p-cymene) complexes of ruthenium(II) containing N-alkylphenothiazines.

Three new ruthenium(II) complexes 1-3 containing N-alkylphenothiazine molecules were synthesized by reaction of [RuCl(2)(η(6)-p-cymene)](2) with chlorpromazine hydrochloride (1), trifluoperazine dihydrochloride (2) or thioridazine hydrochloride (3). The compounds of the general formula L[RuCl(3)(η(6)-p-cymene)] were characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H and (13)C NMR). Complex 2 was structurally characterized by single crystal X-ray diffraction.

New ruthenium(II) complexes with N-alkylphenothiazines: synthesis, structure, in vivo activity as free radical scavengers and in vitro cytotoxicity.

Three new complexes of the general formula L[RuCl(3)(DMSO)(3)] (1-3), where L = chlorpromazine hydrochloride, trifluoroperazine dihydrochloride or thioridazine hydrochloride, were prepared and characterized by elemental analysis and spectroscopic methods (FT-IR, UV-Vis, (1)H NMR and (13)C NMR). In addition, the crystal structure of the complex 2 containing trifluoroperazine dihydrochloride was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P2(1)/n, with a = 10.

Complex superstructures of Mo2P4O15.

We report structural studies on Mo(2)P(4)O(15) over the temperature range 16-731 K, which show that it is considerably more complex than revealed by earlier work. Its low-temperature structure has lattice parameters a = 24.1134(6) A, b = 19.

Structural characterization of RE10W22O81 rare-earth tungstates (RE = Ce, Nd).

The single-crystal diffraction study of Ce10W22O81 and powder X-ray diffraction (XRD) experiments on Ce10W22O81 and Nd10W22O81 show that the true space group of these phases is Pbnm, contrary to the previous literature reports of the space groups Pbcn and Pbcm for the rare-earth tungstates (RE = La, Ce, Pr, Nd) with this general formula. The structure contains rare-earth cations in seven-, eight- and ninefold coordination. W atoms are found in corner-sharing WO5 groups, and also in WO6 and WO7 polyhedra which share edges and corners to form W6O17 units.

Structural chemistry of (PPh4)2M(WS4)2 materials.

In this paper we discuss the structural chemistry of (PPh(4))(2)M(WS(4))(2) (M = Co, Ni, Zn) materials. For M = Ni we and others have been unable to grow single crystals and we report the structure determination from powder diffraction. The material is triclinic (P1, a = 9.

Structural study of polymorphs and solvates of finasteride.

NMR and XRD data are reported for several new forms of finasteride, including the results of complete structure determinations for three solvates. Form III of finasteride, hitherto only mentioned in the patent literature, and a new anhydrous form designated Form X, have been found in mixtures of polymorphs and their (13)C NMR chemical shifts obtained. The results demonstrate that the crystallographic asymmetric units contain three molecules and one molecule, respectively.

Simultaneous anion and cation binding by a simple polymer-bound ureidopyridyl ligand.

A polymer-supported ligand capable of simultaneous anion and cation binding is reported along with X-ray crystallographic data showing potential binding modes.

Modular nanometer-scale structuring of gel fibres by sequential self-organization.

Ag(I) and Cu(II) complexes of a series of simple bis(urea) ligands form soft metallogels. X-ray crystallographic results suggests that the gels' structure is based on hydrogen bonding to counter anions and thus suggests a route to tunable gel rheological properties.

Mo2P4O15--the most complex oxide structure solved by single crystal methods?

We report the crystal structure and phase transitions of Mo2P4O15 which, despite a simple chemical formula, has 441 crystallographically unique atoms in its asymmetric unit and thus has the most complex structure of any extended oxide reported to date.

Beyond classical applications of powder diffraction.

This article provides a short tutorial review of how laboratory powder diffraction methods can be used to establish a variety of "non-traditional" pieces of information about solid state materials-information beyond simple phase identification or structure determination at a specific temperature. The examples show how unique insights into synthetic pathways, reaction mechanisms, reaction kinetics, polymorphism, phase transitions and physical properties can be obtained for a variety of different types of materials.