Materials Literature
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The Raman spectra of ion-implanted highly oriented pyrolytic graphite (HOPG) are reported, in which an additional mode at 1083 cm−1 and three doublet structures in the positions of ∼1350, ∼2450, and ∼2710 cm−1 are revealed. Noticeable frequency shifts are observed for all the Raman bands between the spectra excited wi…
Silicon has long been synonymous with semiconductor technology. This unique role is due largely to the remarkable properties of the Si-SiO_2 interface, especially the (001)-oriented interface used in most devices. Although Si is crystalline and the oxide is amorphous, the interface is essentially perfect, with an extr…
X-ray photoemission spectroscopy measurements were executed to compare the nature of defects in SrBi2Ta2O9 (SBT) and Bi4Ti3O12 (BTO) films. In the SBT film, it was found that the oxygen ions at the metal–oxygen octahedra were much more stable than those at the Bi2O2 layers. On the other hand, for the BTO film, oxygen…
Crystal structures of ferroelectric materials of stoichiometric SrBi2Ta2O9 (TC=300 °C) and Sr-deficient-and-Bi-excess Sr0.8Bi2.2Ta2O9 (TC=400 °C) were refined by neutron powder diffraction. Bi2O2 layer and TaO6 octahedra are considerably distorted and atomic displacements along the a axis cause ferroelectric spontaneo…
The ideal shear strength is the minimum stress needed to plastically deform an infinite dislocation-free crystal and is an upper bound to the strength of a real crystal. We calculate the ideal shear strengths of Al and Cu at zero temperature using pseudopotential density functional theory within the local density appr…
A novel two-dimensional system of colloidal particles with absolutely calibrated magnetic interaction is used to investigate static and dynamic properties at the 2D crystal to liquid phase transition. We observe two successive transitions from the solid to the liquid phase with an intermediate hexatic phase, in perfec…
Poly(o-toluidine) films were electrochemically synthesized on Pt electrodes at a constant potential (0.75 V versus Ag/AgCl) from a deoxygenated aqueous solution of 0.1M toluidine dissolved in 0.1M KCl. To form permselective polymeric film electrodes, poly(o-toluidine) films at different thicknesses were prepared by va…
Conducting films of dodecylbenzenesulfonic (DBSA)-doped polyaniline/polyimide (PANI/PI) blends with various compositions were prepared by solvent casting followed by a thermal imidization process. Electrical and physical properties of the blends were characterized by infrared spectroscopy, an X-ray diffraction techniq…
Molecular weight increase via chain extension reactions of poly(ethylene terephthalate) with commercially available diepoxides was studied in a custom-made laboratory scale reactor and a Brabender rheomixer under reactive blending conditions. The products were characterized by carboxylic end group analysis, intrinsic…
Polyacrylonitrile (PAN) was modified with cobalt chloride at 90°C for 5 min. The carbon films prepared from original and modified PAN films were carbonized up to 1300°C. The structure of the resulting carbon film was studied using X-ray diffraction and Raman spectroscopy. The stacking size obtained from X-ray diffract…
Gas-phase ionization and attachment energy (IE and AE) values of the first few oligomers of 2-thienyl ketone have been determined experimentally. The assignments of the ultraviolet photoelectron spectra agree with the results of theoretical HF/6-31G** calculations. The constant value of the HOMO energy allows extrapol…
The electrochemical promotion (EP) of propene combustion has been studied over a platinum film catalyst supported on sodium β‘ ‘-alumina. Fully reversible promotion and poisoning are observed as a function of catalyst potential (i.e., sodium coverage), the precise behavior being dependent on reactant partial pressures…
Formal [3+2] cycloaddition reactions between various aldehydes and 2-phosphino-1-zirconaindene ( 1 ) lead to stable anionic zwitterionic zirconocene complexes. Extension of this method to the reaction of internal or terminated aldehyde containing dendrimers with 1 allows the preparation of the first dendrimers and mul…
Self-assembled structures in solvent-cast mixtures of polystyrene- block -poly(ethylenepropylene) (PS−PEP) and polystyrene- block -(partially hydrogenated polyisoprene) (PS−HPI) were investigated by small-angle X-ray scattering and transmission electron microscopy. Various self-assembled structures were observed in th…
Stable gold nanoparticles of 2-nm diameter are prepared in water by chemical reduction of AuCl 4 - by NaBH 4 in the presence of CS 2 without adding any other stabilizers. The nanoparticles are proved to be Au and not Au sulfides by electron diffraction. In their UV−visible absorption spectra the surface plasmon (SP) b…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTPolycarbonates from Sugars: Ring-Opening Polymerization of 1,2-O-Isopropylidene-d-Xylofuranose-3,5- Cyclic Carbonate (IPXTC)Youqing Shen, Xianhai Chen, and Richard A. GrossView Author Information Polytechnic University, Polymer Rese…
In the design of advanced polymeric biomaterials there is a need to tailor the surface chemistry of the biomaterial to elicit beneficial interactions with cells and biomolecules. To facilitate the fabrication of complex biomaterial surfaces, we have previously described the synthesis and application of a poly(lactic a…
High molar mass polymacromonomers based on methacryloyl end-functionalized oligo methacrylates ( M n = 2410 g/mol) adopt the conformation of wormlike cylindrical brushes. Comparison of the absolute molar mass, M w, determined by static light scattering and the contour length, L w, of the molecules measured by SFM in t…
Sequential adsorption of polyanions and polycations was used to make a five-component energy/electron-transfer cascade, which mimics some of the functions of natural photosynthetic assemblies. The photon antenna part of the system consists of coumarin- and fluorescein-derivatized poly(allylamine hydrochloride) (Coum-P…
The wet oxidation of organic compounds composed only of C, H, and O, dyes, amides, and water-soluble polymers is discussed to clarify the basic nature of this process. The reactivity of the organic compounds composed of C, H, and O, dyes, and some amides was correlated well with their carbon content in the molecule (C…