Materials Literature
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Methane activation is a crucial step in the conversion of methane to valuable oxygenated products. In heterogeneous catalysis, however, methane activation often leads to complete dissociation: If a catalyst can activate the first C–H bond in CH4, it can often break the remaining C–H bonds. In this study, using density…
A highly ordered multilayer film was formed by casting chloroform solutions of an ionic complex between a dimethyldioctadecylammonium (DODA) and a phosphomolybdate anion PMo12O403− (PMo12) on a glassy carbon electrode and solid substrates (CaF2, quartz, and borosilicate glass). A well-ordered lamellar superlattice str…
We discuss atomistic simulations of dislocation processes in copper based on effective medium theory interatomic potentials. Results on screw dislocation structures and processes are reviewed with particular focus on point defect mobilities and processes involving cross slip. For example, the stability of screw disloc…
A model is developed in the form of one or two partial differential equations (master Smoluchowski-like equations) that describe evolution of the size distribution of polymer species formed in a step-growth polymerization of an AB 2 monomer. Groups B react with a substitution effect; i.e., they are initially equally r…
Photon-emission spectra have been measured for individual titania-supported gold particles excited by the electron current from an STM tip. Depending on the interaction strength between tip and cluster, the emission behavior changes from excitations with Mie-plasmon character at 2.3 eV to modes of tip-induced plasmons…
Lasing is reported at the edge and in the middle of the selective reflection band produced in the visible region of the spectrum for the cholesteric phase of a lyotropic liquid crystal formed from an optically active polyisocyanate in toluene. This is the first observation of lasing from a stiff polymer based lyotropi…
Amorphous phase in semicrystalline poly(ethylene terephthalate) (PET) was investigated via its physical aging behavior. It was found that when the degree of crystallinity ( f c w ) was within a definite range, there were dual amorphous regions with quite different characters in semicrystalline PET: free amorphous regi…
We investigated temperature $(T)$- and magnetic field-dependent optical conductivity spectra $\ensuremath{\sigma}(\ensuremath{\omega})$ of a ${\mathrm{La}}_{5/8\ensuremath{-}y}{\mathrm{Pr}}_{y}{\mathrm{Ca}}_{3/8}{\mathrm{MnO}}_{3}(y\ensuremath{\approx}0.35)$ single crystal, showing intriguing phase coexistence at low…
Submicrometric hollow spheres with mesoporous walls were prepared by applying the synthesis of MSU-X type mesoporous silica at neutral pH. The application of ultrasound in the proper power range, to a mixture of nonionic polyoxyethylene surfactant and unreacted silicon alkoxide (tetraethylorthosilicate) gives a stable…
This paper discusses some current trends in computational materials science, especially the striving to forge links between modelling activities at various length and timescales. At the atomistic scale, methods based on quantum mechanical, especially density-functional, theories for electronic properties link to atomi…
The photoorientation process in a polyester with 4-cyano-4‘-alkoxyazobenzene side group and long methylene spacers in the side and the main-chain was studied as a function of irradiation with linearly polarized light of 488 nm under systematic variation of the power density and temperature. This model polymer is chara…
Most previous atomistic simulations of heterophase interfaces have neglected misfit , the discrepancy between the interatomic length scales parallel to the interface of the two phases. The obstacles to quantitative calculations of interface energies in the presence of misfit are assessed. The most straightforward appr…
A characteristic feature of the physics in transition-metal oxides is that the charge, spin, and lattice degrees of freedom are strongly coupled. The key to understanding these strong mutual couplings is the orbital degree of freedom (ODF), which plays a crucial role in controlling the phases and various physical prop…
Temperature programmed isotopic exchange (TPIE) of oxygen and pulsed methane combustion experiments were used to investigate the contribution of oxygen from the support in the methane combustion reaction over alumina- and zirconia-supported palladium. TPIE experiments show that PdO is more active than reduced palladiu…
Measurements of electrical resistance, magnetization, ac magnetic susceptibility, and ferromagnetic resonance of ${\mathrm{La}}_{0.82}{\mathrm{Ca}}_{0.18}{\mathrm{MnO}}_{3}$ single crystal were carried out at temperatures below and above the Curie temperature, ${T}_{C}=180\ifmmode\pm\else\textpm\fi{}1\mathrm{K}.$ A st…
ZnO/GaN heterointerfaces are engineered to control the polarity of ZnO films grown by plasma-assisted molecular beam epitaxy on Ga-polar GaN templates. The polarity of ZnO films is determined both by coaxial impact collision ion scattering spectroscopy (CAICISS) and by convergent beam electron diffraction (CBED). Pola…
Hydride abstraction by triphenylcarbenium cations in the presence of terminal alkynes and alkenes results in hydrosilylation at room temperature on hydride-terminated porous silicon surfaces, leading to alkenyl- and alkyl-terminated surfaces, respectively. A wide range of surface terminations are possible as the react…
The ${D}^{*}$ Raman band of single-wall carbon nanotubes aligned by shear flow in a polymer matrix has been measured as a function of tensile strain. The Raman intensity varies with the optical polarization direction, an effect which is used here to assess the degree of tube alignment. The strain dependence of the Ram…
Transition metal (Me = V, Fe, and Cr) incorporated into MCM-41 mesoporous molecular sieves (Si/Me = 80) have been synthesized by hydrothermal methods and were loaded with TiO 2 utilizing a sol−gel technique. These materials were found (refs 22, 23) to be photoactive for the destruction of organics with visible light.…
Electronic and structural calculations for atomic clusters present many challenges for traditional theoretical methods. While the computational framework for ground-state properties of clusters is relatively well established, calculations for excited states remain difficult. In this paper we implement a linear-respons…