Materials Literature
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Spinning a yarn: A biomimetic approach to hierarchically structured silica composite fibers mimics the process of bioglass fiber formation. The fibers, which tend to form bundles (see image), are formed in seconds by combining the self-assembly of peptide–polymer conjugates with peptide-directed silicification. These…
A procedure was developed for the preparation of β-monobromo-tetraphenylporphyrin (BrTPP) in a greatly improved yield from the selective bromination of tetraphenylporphyrin (TPP) by NBS. BrTPP was successfully employed as a versatile synthon for convenient synthesis of a wide range of β-monofunctionalized porphyrins w…
On-stream deactivation during a water gas shift (WGS) reaction over gold supported on a ceria−zirconia catalyst was examined. Although the fresh catalyst has very high low temperature (<200 °C) for WGS activity, a significant loss of CO conversion is found under steady-state operations over hours. This has been shown…
The work presented here describes the first steps toward designing a thermally robust surface-enhanced Raman spectroscopy (SERS) substrate with the potential to conduct in situ monitoring of catalytic reactions. Nanosphere lithography (NSL) fabricated SERS substrates were coated with thin (0.2−1.0 nm) films of atomic…
Novel mesoporous tungsten trioxide films with enhanced incident photon-to-current conversion efficiencies have been prepared by a sol−gel route from an aqueous precursor solution containing peroxopolytungstic acid (PPTA). For films heated in air at 500 °C, it was found that film texture depended in a precise and repro…
Recent advances in nanoscience have raised interest in the minimum bit size required for classical information storage, i.e. for bistability with suppressed quantum tunnelling and energy barriers that exceed ambient temperatures. In the case of magnetic information storage much attention has centred on molecular magne…
AlO(OH) hollow spheres are realized via a water-in-oil (w/o) microemulsion, applying the liquid-to-liquid-phase boundary of the micellar system as a template. Scanning electron microscopy, transmission electron microscopy (TEM), and dynamic light scattering analyses show the presence of nonagglomerated hollow spheres…
We report optimized chemical vapor deposition growth procedures that can produce arrays of individual single walled carbon nanotubes (SWNTs) in horizontal configurations with perfect linear shapes to within experimental uncertainties and with levels of alignment >99.9%. This process also enables simultaneous growth of…
We describe a self consistent magnetic tight-binding theory based in an expansion of the Hohenberg-Kohn density functional to second order, about a non spin polarised reference density. We show how a first order expansion about a density having a trial input magnetic moment leads to the Stoner--Slater rigid band model…
We examine whether essence and quantitative aspects of electronic excitation spectra are correctly captured by an effective low-energy model constructed from an {\em ab initio} downfolding scheme. A global electronic structure is first calculated by {\em ab initio} density-functional calculations with the generalized…
In this paper we introduce a novel method for fabricating MgB$_2$/MgO multilayers and demonstrate the potential for using them as a new model for disordered superconductors. In this approach we control the annealing of the MgB$_2$ to yield an interesting new class of disordered (amorphous) superconductors with relativ…
We present a procedure to study the switching and the stability of an array of magnetic nanoparticles in the dynamical regime. The procedure leads to the criterion of multi-switching stability to be satisfied in order to have stable switching. The criterion is used to compare various magnetic-field-induced switching s…
Modulation of charge carrier dynamics and hence electrical conductivity of solids by photoexcitation has been a rich field of research with numerous applications. Similarly, electric and magnetic field assisted enhancement of conductivity are of fundamental importance and technological use. Hole doped manganites of th…
Mechanical properties of organic/ inorganic thin-films prepared from bridged silicon precursors have been investigated. The Young's modulus follows a linear decay when porosity is introduced, a unique observation as compared to traditional organosilicates. Remarkably, in the dense state, fracture energies of 15–17 J.m…
This work reports the discovery of room-temperature ferromagnetism in $5--9\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ sized ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x}{\mathrm{O}}_{2}$ nanoparticles $(0.01\ensuremath{\leqslant}x\ensuremath{\leqslant}0.20)$ prepared using a sol-gel based chemical method at room tem…
We calculate electron-hole generation and recombination rates for Coulomb scattering (Auger recombination and impact ionization) in zero band-gap graphene. The conduction and valence band dispersion relation in graphene together with energy and momentum conservation requirements restrict the phase space for Coulomb sc…
The spatial charge arrangement of a typical quasi-two-dimensional organic conductor alpha-(BEDT-TTF)2I3 is revealed by single crystal structure analysis using synchrotron radiation. The results show that the horizontal stripe type structure, which was suggested by mean field theory, is established. We also find the ch…
We propose that the driving force of the ultrafast crystalline-to-amorphous transition in phase-change memory alloys is caused by strained bonds existing in the (metastable) crystalline phase. For the prototypical example of Ge 2 Sb 2 Te 5 , we demonstrate that upon breaking of the longer Ge–Te bond by photoexcitation…
Thin film metal-insulator-metal junctions are used in a novel approach to investigate the dissipation of potential energy of multiply charged ions impinging on a polycrystalline metal surface. The ion-metal interaction leads to excited electrons and holes within the top layer. A substantial fraction of these charge ca…
In this paper the effect of the chemical pressure induced by the Sr replacement for Ca in the La1.4Sr1.6Mn2O7 lattice is directly probed by means of neutron diffraction as a function of temperature. The results show a progressive change of the magnetic coupling from ferromagnetic to antiferromagnetic by increasing the…