Materials Literature
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We study in a Landau-de Gennes approach the biaxial structure of a nematic point defect with topological charge M = + 1. We aim to illuminate the role of the confining boundaries in determining the fine structure of the defect. We show that there are different regimes associated with different values of the ratio betw…
A shift in plasmon surface resonance is measured for colloidal solutions of gold nanoparticles upon adsorption of polyampholyte (gelatin). It is demonstrated that the shift in wavelength of the absorption maximum can quantitatively yield measurements of the adsorbed amount as well as information about the structure of…
Non-equilibrium dynamics in an interacting Fe-C nanoparticle sample, exhibiting a low temperature spin glass like phase, has been studied by low frequency ac-susceptibility and magnetic relaxation experiments. The non-equilibrium behavior shows characteristic spin glass features, but some qualitative differences exist…
Monte Carlo simulations of a model for $γ$-Fe$_2$O$_3$ (maghemite) single particle of spherical shape are presented aiming at the elucidation the specific role played by the finite size and the surface on the anomalous magnetic behaviour observed in small particle systems at low temperature. The influence of the finit…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTemplate Synthesis of Asymmetrically Mesostructured Platinum NetworksHyun June Shin, Ryong Ryoo, Zheng Liu, and Osamu TerasakiView Author Information Materials Chemistry Laboratory, Department of Chemistry School of Molecular Science-BK21 Korea Advanced Institute of Sc…
We present an experimental investigation on the creep behavior of molten polypropylene organically modified clay nanocomposites. The nanocomposite hybrids were prepared by melt intercalation in an extruder in the presence or absence of a compatibilizer. They were subsequently annealed and simultaneously characterized…
The properties of a material depend on the type of motion its electrons can execute, which depends on the space available for them (i.e., on the degree of their spatial confinement). Thus, the properties of each material are characterized by a specific length scale, usually on the nanometer dimension. If the physical…
A series of homologous statistical polymethacrylate comb copolymers with tail-end 4-(dimethylamino)pyridinium ionic groups were synthesized by partial quaternization of high molar mass poly(12-bromododecyl methacrylate). The copolymers of lower ion content are found to be biphasic by differential scanning calorimetry,…
The electronic state of ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ below the Verwey transition has been studied by x-ray resonant scattering at the iron K edge of the forbidden (0 0 2) and (0 0 6) reflections. These reflections are permitted by the anisotropy of the iron anomalous scattering factor. The energy and the azimut…
[figure: see text] A biphasic protocol for the catalytic olefin epoxidation with Mimoun-type complexes [MoO(O2)2(OPR3)] (1) was recently patented by BASF. Density-functional calculations have been carried out to identify potentially active species in addition to the parent complex 1. It has been found that the (mu 2,e…
Rb 2 Bi 8 Se 13 ( I ), Cs 2 Bi 8 Se 13 ( II ), CsBi 3.67 Se 6 ( III ), and BaBi 2 Se 4 ( IV ) were synthesized by direct combination reactions of the A/Se ( A = Rb, Cs, Ba) and Bi 2 Se 3 at ≥650 °C. Their structures were determined by single-crystal X-ray diffraction. Rb 2 Bi 8 Se 13 and Cs 2 Bi 8 Se 13 are isostructu…
High-pressure X-ray diffraction experiments on cubic ZrMo 2 O 8 have shown that the material undergoes a first-order phase transition involving an 11% volume decrease between 0.7 and 2.0 GPa under quasi-hydrostatic conditions. The transition is reversible upon decompression, but shows considerable hysteresis. Similar…
The anisotropic, two-dimensional structure of the compounds A 2 BaCu 8 Te 10 (A = K, Rb, Cs) fits the description of a “phonon glass electron crystal” (PGEC) which is proposed to be a desirable feature of a good thermoelectric material. It contains Cu 8 Te 12 pentagonal dodecahedral cages filled with Ba 2+ atoms. Thes…
Using a laser monitoring observation technique, the solubilities of 4-methylbenzoic acid in N -methyl-2-pyrrolidone, N, N -dimethylformamide, N, N -dimethylacetamide, trichloromethane, acetic acid, and water were measured by a synthetic method at temperatures ranging from 288 K to 370 K at atmospheric pressure. A solu…
Lattice constants, bulk moduli, band gaps, electronic bonding, and the stability of 20 new nitrides with spinel structure are studied by first-principles calculations. Double nitrides ${\mathrm{AB}}_{2}{\mathrm{N}}_{4}$ are found to be stable when the counterparts ${\mathrm{BA}}_{2}{\mathrm{N}}_{4}$ are metastable exc…
A series of Fe−zeolite-beta (Fe−BEA and 57 Fe−BEA) has been prepared either by exchanging BEA (Si/Al = 12.5) with Fe(NO 3 ) 3 or by impregnation. The identification of Fe species in Fe−BEA has been carried out by temperature-programmed reduction (TPR) with H 2 or CO and Mössbauer and DRIFT spectroscopies after various…
Wormhole HMS silica molecular sieves with average framework pore sizes in the range 2.9 to 4.1 nm were assembled from 4:1 molar mixtures of TEOS as the inorganic precursor (I o ) and dodecylamine as the structure-directing surfactant (S°) in 63:27 (v/v) water/ethanol. Increasing the assembly temperature from 25 °C to…
A series of double-comb, disubstituted polysiloxane polymers have been prepared containing oligoethylene oxide units, CH 3 (OCH 2 CH 2 ) n (CH 2 ) 3 −, in the side chains. These polymers were doped with LiN(SO 2 CF 3 ) 2 (LiTFSI, 1 ), and conductivities of the polymer-salt complexes were determined as a function of te…
The foaming of thin (∼100 μm) polysulfone (PSU), poly(ether sulfone) (PES), and cyclic olefin copolymer (COC) films using carbon dioxide as a physical blowing agent has been studied. Microcellular foam morphologies were obtained by saturating the polymer with carbon dioxide and heating the sample above the glass trans…
A theory for the ab initio calculation of all-electron NMR chemical shifts in insulators using pseudopotentials is presented. It is formulated for both finite and infinitely periodic systems and is based on an extension to the Projector Augmented Wave approach of Bloechl [P. E. Bloechl, Phys. Rev. B 50, 17953 (1994)]…