Materials Literature
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Mössbauer and Raman spectroscopies, calorimetric measurements, the LIESST effect (light induced excited spin state trapping) and dynamics of the high-spin (HS) to low-spin (LS) relaxation have been investigated in order to thoroughly study the spin-crossover compounds of formula {Fe(L)[H 2 B(pz) 2 ] 2 }, where L = 2,2…
Organized monolayer films of a manganese tetraphenylporphyrin have been prepared and used as supported oxidation catalysts. Manganese 5,10,15,20-tetrakis(tetrafluorophenyl-4'-octadecyloxyphosphonic acid) porphyrin (1) has been immobilized as a monolayer film by a combination of Langmuir-Blodgett (LB) and self-assemble…
On the basis of the possibility that there might exist a mixed composition of the Y(As,Nb,P,V)O 4 system of better luminescent performance than the single-compound phosphors at the VUV excitation, a solution combinatorial chemistry synthesis and characterization was employed in the present investigation. Quaternary an…
An anomalous thermalization effect induced by optical excitation of Er 3+ ions in nanocrystals of Y 2 O 2 S is investigated. Due to the absence of low-energy phonon modes in the 20−40 nm crystals we studied, phonon relaxation is restricted, and as a result, the intensity of hot bands that originate from the upper crys…
The reaction of superoxide with nitrogen monoxide has been reinvestigated. Photolysis of alkaline peroxynitrite solutions results in the formation of superoxide and nitrogen monoxide, which subsequently react at a rate of (1.5 ± 0.1) × 10 10 M -1 s -1 . When hydrogen peroxide is photolyzed in the presence of nitrogen…
We report the results of magnetic measurements for the solid solution Ce$_2$Au$_{1-x}$Co$_x$Si$_3$. The results reveal that this solid solution is characterized by a magnetic phase diagram (plot of magnetic transition temperature versus $x$) unusual for Kondo lattices. In particular, the spin-glass freezing induced by…
We present a new process for the synthesis of colloidal europium-doped yttrium vanadate with a particle diameter of about 10 nm. Nanocrystals are produced by precipitation of citrate complexes of rare-earth salts with sodium orthovanadate. NMR and IR studies show that the interaction between citrate ligands and lantha…
Four metakaolins were prepared by calcination of a natural Spanish kaolin (Navalacruz deposit, Zamora province) at 600, 700, 800, and 900 °C. These four metakaolins, more reactive than the parent kaolin, were submitted to acid and alkaline activations. Acid activation was carried out with 6 M HCl at room temperature a…
Gold nanoparticles (NPs) were prepared by reduction with salicylic acid in aqueous solution. The resulting dispersions were found to contain a mixture of flat triangular/hexagonal and smaller close-to-spherical NPs. As expected from theoretical considerations, such nanocolloids display two clearly differentiated surfa…
The electrochemistry of horse heart cytochrome c was studied by cyclic voltammetry at a glassy carbon electrode modified with single-wall carbon nanotubes (SWNTs). A pair of well-defined redox waves was obtained in cytochrome c aqueous solution at an activated SWNT film-modified electrode. The optimal conditions for a…
This paper describes a general approach that generates nanoscale hollow structures of metals by reacting solutions of appropriate salt solutions with solid templates of a more reactive metal. Typical examples include Au 3+, Pt 2+, and Pd 2+ salts and nanoparticles or nanowires of silver. The morphology, void space, an…
The title compound, trimercury(II) bis[selenite(IV)] selenate(VI), contains three crystallographically inequivalent HgII cations with coordination numbers of eight (denoted Hg1 and Hg2) and five (denoted Hg3). The corresponding coordination polyhedra around the metal atoms might be described as intermediates between a…
First-principles pseudopotential calculations using plane-wave basis functions have been made to quantitatively evaluate the formation energy of Cr/Al vacancies in ${\mathrm{MgCr}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{MgAl}}_{2}{\mathrm{O}}_{4}.$ Relaxation of atoms within the second nearest neighbor shell of the vacanc…
Abstract Polysiloxane diblock copolymers containing a pure polysiloxane backbone were prepared by the functionalization of poly(dimethylsiloxane)‐ b ‐poly(methylvinylsiloxane) copolymers. The copolymers were obtained by the sequential anionic copolymerization of either 1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinylcyclotetras…
Three molecules with olefinic deuterons were obtained through H−D exchange of the C3 proton on the central bridging double bond of spiropyran photomerocyanines with deuterium oxide solution. Quadrupole coupling parameters were determined by simulation of the spinning sideband manifolds in spectra obtained using solid-…
A combination of reverse Monte Carlo, molecular dynamics, and lattice dynamics simulations were used to obtain structural and thermodynamic data for low-density amorphous ice. A thermodynamically discontinuous transformation to a phase with properties and a structure consistent with supercooled liquid water is found t…
The tetraamide ligand, DOTA-tetra(glycine ethyl ester), forms complexes with the lanthanide(III) cations that exist in solution predominantly as the square antiprism structure with single, slowly exchanging inner-sphere water molecule. Variable-temperature 1H and 17O NMR studies revealed that the bound water lifetimes…
Simulated annealing, in the form of temperature-controlled molecular dynamics, has been successfully applied to macromolecular X-ray structure optimization. The theory and practice of the method are reviewed, and some recent improvements are described.
The surfaces of kaolinite have been modified through intercalation with deuterated dimethylsulfoxide (d-DMSO). X-ray diffraction shows the kaolinite to be expanded from 7.2 to 11.19 Å. Modification of the surface has been explored through (a) changes to the hydroxyl surfaces of the kaolinite and (b) through changes to…
Pyrochlores have the striking feature that their radiation resistance is highly dependent on their composition. In this work, the propensity of a pyrochlore to transform to a cation-disordered structure and the influence of titanium ions is ascertained from the mechanisms of defect formation. A detailed study of defec…