Materials Literature
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Deviations of the coordination arrangement of vanadyl complexes from a regular square pyramid are thought to influence, among other things, their biological function. Such structural distortions have been found to be reflected characteristically in EPR spectra (Cornman et al. Inorg. Chem. 1997, 3 66, 6401). In this wo…
The program PSEUDO provides tools for the systematic search of pseudosymmetry, based on group±subgroup relations between space groups (Igartua et al., 1996). For a crystal structure L, speci®ed by its space group U, the cell parameters and the coordinates of the atoms in the asymmetric unit, the program searches for p…
The effect of pressure on the thermal dependence of the magnetic susceptibility has been investigated in the 2,2‘-bipyrimidine (bpm)-bridged iron(II) complexes of formula {[Fe(L)(NCX) 2 ] 2 bpm} (X = S and Se; L = bpm and bt (2,2‘-bithiazoline)) and [Fe(bpm)(NCX) 2 ] n . At ambient pressure, the compound {[Fe(bpm)(NCS…
Rietveld refinements of corundum, a rutile and anatase nanocrystalline synthetic mixture, and gypsum, on laboratory energy dispersive X-ray diffraction (EDXD) data are reported. Cell parameters, positional and displacement parameters are in reasonable agreement with single-crystal reference data, despite the rather po…
The importance of local (intraresidue) effects in determining the stability of the collagen triple helix has been investigated with special reference to the role played by hydroxyproline. To this end the dipeptide analogues of L-proline (ProDA), 4(R)-hydroxy-L-proline (HypDA), and 4(R)-fluoro-L-proline (FlpDA) have be…
A method is presented for fast and non-destructive characterization of the individual grains inside bulk materials (powders or polycrystals). The positions, volumes and orientations of hundreds of grains are determined simultaneously. An extension of the rotation method is employed: a monochromatic beam of high-energy…
The thermal degradation of the biodegradable bacterial polyesters poly(3-hydroxybutyrate), PHB, poly(3-hydroxyvalerate), PHV, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), 0-21 mol % of hydroxyvalerate, was studied. At moderately low temperatures (170-200 degrees C), the main product is a well-defined oligomer, es…
We present a method for calculating the kinetic energy of localised functions represented on a regular real space grid. This method uses fast Fourier transforms applied to restricted regions commensurate with the simulation cell and is applicable to grids of any symmetry. In the limit of large systems it scales linear…
We derive an equilibrium statistical theory for the macroscopic description of a ferromagnetic material at positive finite temperatures. Our formulation describes the most-probable equilibrium macrostates that yield a coherent deterministic large-scale picture varying at the size of the domain, as well as it captures…
A fast and non-destructive method for generating three-dimensional maps of the grain boundaries in undeformed polycrystals is presented. The method relies on tracking of micro-focused high-energy X-rays. It is verified by comparing an electron microscopy map of the orientations on the 2.5 × 2.5 mm surface of an alumin…
We have studied the structural, magnetic and electrical properties of hole-doped cobaltites with compositions, La 0.7 (Ca 1- x Ba x ) 0.3 CoO 3 ( x = 0.0, 0.5 and 1.0). Due to the large difference in size between the Ca and Ba ions (size mismatch), these compounds show interesting changes in the magnetic and transport…
A series of novel dinuclear gold(II) complexes having an unsupported Au(II)-Au(II) bond with well-defined oxidation state at the gold center were synthesized. Red shifts in both the low-energy absorption and emission bands were observed upon increasing the donor ability of the coordinated halogen atoms.
Copper(II) 3',4'-bis(N,N'-oxamato)terthiophene has been synthesized and electropolymerized. The copper(II)-complex centers are not affected by the polymerization process, which involves coupling between Calpha carbon atoms of the terthiophene units and leads to a new conjugated polymer consisting of polythiophene chai…
Binary metal imidazolates of the group 10 metals have been prepared and typically found amorphous. However, the intermediacy of a number of (poly)crystalline species during their formation has been evidenced; their selective preparation and characterization, by chemical, spectroscopic, and thermal methods and their st…
Abstract Copper(II), nickel(II), cobalt(III) and iron(III) complexes of D ‐glucosamine, and their complexes with α‐glycine were synthesized. The eight novel metal complexes were characterized by means of IR, electronic absorption and 1 H NMR spectroscopy. The surface‐enhanced Raman scattering (SERS) spectra of these c…
Evidence for an unusual double charge disproportionation, Mn 4+ + Co 2+ → Mn 3+ + Co 3+ → Mn 4+ + Co 2+ , is observed in nanocrystalline LaMn 0.5 Co 0.5 O 3 synthesized by a low-temperature method and annealed in the temperature range 200–1300 °C. The Curie temperature of nanocrystalline LaMn 0.5 Co 0.5 O 3 is increas…
The influence of pressure on the crystal structure of LaGaO 3 has been studied using synchrotron x-ray diffraction. At atmospheric pressure LaGaO 3 has an orthorhombic structure in Pnma and undergoes a first-order phase transition to a rhombohedral structure near 2.5 GPa. The transition is reversible and the orthorhom…
We report O and Ca K-edges x-ray absorption near edge structure (XANES) spectra of Ba 1- x Ca x TiO 3 ( x = 0.01 and 0.08), BaTiO 3 and CaTiO 3 and the electronic structure of Ba 0.875 Ca 0.125 TiO 3 obtained by first-principles calculation. The characteristic features in the O K-edge XANES spectra of these ferroelect…
Fitting B2 bridges in porphyrins (see picture) can be achieved by reaction of dilithiated porphyrins with B2Cl4 as well as by reductive elimination from diborylporphyrins. Coordination takes place under rectangular distortion of the porphyrin framework.
Both the low (γ)- and high (γ′)-temperature polymorphs of Bi2MoO6 are oxide ion conductors. The γ′ conductivity at 300 °C is comparable to that of yttria-stabilized zirconia (YSZ) while its activation energy, 0.510(2) eV, is much less than that of YSZ, 0.79 eV, and is lower than that of the best low temperature oxide…