Materials Literature
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Using an adiabatic approximation method, which searches for Tomlinson model-like instabilities for a simple but still realistic model for two crystalline surfaces in the extremely light contact limit, with mobile molecules present at the interface, sliding relative to each other, we are able to account for the virtual…
Transmission-electron microscopy has shown that the strongly piezoelectric material ${\mathrm{PbZr}}_{0.52}{\mathrm{Ti}}_{0.48}{\mathrm{O}}_{3}$ separates into two phases at low temperatures. The majority phase is the monoclinic phase previously found by x-ray diffraction. The minority phase, with a nanoscale coherenc…
We propose a scheme for numerically computing collective-mode spectra for large-size systems, using a reformulation of the random-phase approximation. In this study, we apply this method to investigate the spectrum and nature of the spin-waves of a (III,Mn)V diluted magnetic semiconductor. We use an impurity band pict…
Electronic States of Si and Ge QDs of 5 to 3127 atoms with saturated shapes in a size range of 0.57 to 4.92 nm for Si and 0.60 to 5.13 nm for Ge are calculated by using an empirical tight binding model combined with the irreducible representations of the group theory. The results are compared with those of Si and Ge q…
The ferromagnetic structure of ${\mathrm{BiMnO}}_{3},$ ${T}_{c}=105 \mathrm{K},$ has been determined from powder neutron-diffraction data collected at 20 K on a sample synthesized at high pressures using a cubic anvil press. ${\mathrm{BiMnO}}_{3}$ is a distorted perovskite that crystallizes in the monoclinic space gro…
Thin films of the vanadium oxides, V2O5, VO2, VOx (x = 2.00–2.50) and V6O13 were prepared on glass substrates by atmospheric pressure chemical vapour deposition (APCVD) of vanadium tetrachloride and water at 400–550 °C. The specific phase deposited was found to be dependent on the substrate temperature and the reagent…
The isometric pyrochlore structure, ${A}_{2}{B}_{2}{\mathrm{O}}_{7},$ is generally susceptible to radiation damage, but certain compositions are remarkably resistant to radiation damage. In the binary system ${\mathrm{Gd}}_{2}({\mathrm{Ti}}_{2\ensuremath{-}x}{\mathrm{Zr}}_{x}){\mathrm{O}}_{7},$ the radiation resistanc…
Honeycomb-like aligned carbon nanotube films were grown by pyrolysis of iron phthalocyanine. The patterned structure was characterized by a scanning electron micrograph (SEM) and an atomic force micrograph (AFM). Wettability studies revealed the film surface showed a super-hydrophobic property with much higher contact…
In the mid-1970s, surface-enhanced Raman scattering (SERS) was discovered which impacted on surface science and spectroscopy because of its extremely high surface sensitivity. However, SERS had not developed as many people had hoped to be a powerful surface diagnostic technique that can be widely used because of some…
In this paper we investigate the effect of hydrostatic pressure on the electrical conductivity of polypyrrole-polyaniline conductive (protonated) blends of various compositions. Results are presented for thermally aged blends as well. The modification of the conductivity due to pressure is more pronounced in the fresh…
This paper addresses discrepancies between the results of different measurements of the effective tensile strength ( F c ) of liquids, in experiments in which a pulse of tension (or `negative pressure') is created by the reflection of a pressure pulse at a suitable boundary. We show that a key feature of the pressure…
The Somoza-Tarazona density-functional theory is applied to the isotropic-nematic interface of hard spherocylinders with length (L)-to-diameter (D) ratios in the range L/D=5-20. Properties such as the density and orientational order-parameter profiles and the variation of interfacial tension with bulk nematic tilt ang…
We present an experimental method allowing a direct measurement of the local rheological behavior of complex fluids. A magnetic probe is inserted into the bulk of the fluid and submitted to a controlled magnetic force or torque, which induces a mechanical perturbation of the fluid. The geometry of the perturbation can…
In this paper, the relationship between microstructural properties of steels and the material parameters in the Preisach model and in the Jiles-Atherton (JA) model is discussed, in the instance where both models describe quasi-static hysteretic magnetic behaviour. It is shown how the material parameters in both hyster…
Reversible modification of the optical and electrical properties of V 2 O 5 × n H 2 O gel films under the action of an electric field is studied. It is shown that under cathodic polarization ( I = 10 -6 -10 -5 A, t ~10min, film thickness ~10 µm), the films turn from brownish-yellow to red. This internal electrochromic…
Neutron-diffraction measurements in ${\mathrm{L}\mathrm{a}\mathrm{C}\mathrm{r}\mathrm{S}\mathrm{b}}_{3}$ show a coexistence of ferromagnetic and antiferromagnetic sublattices below ${T}_{C}=126\text{ }\text{ }\mathrm{K}$, with ordered moments of 1.65(4) and $0.49(4){\ensuremath{\mu}}_{B}/\mathrm{\text{formula unit}}$,…
A hierarchical self-assembly in comb-shaped supramolecules of conjugated rodlike polymers is reported. The supramolecules consist of poly(2,5-pyridinediyl), acid dopants, and hydrogen bonded alkyl side chains. A thermotropic smectic state with an exceptionally large coherence length is formed without additional solven…
The a.c. conductivity σ ac of polyaniline prepared with a.c. plasma polymerization was studied recently at low angular frequencies (ω⩽1 MHz) (Mathai J et al 2002 J. Phys. D: Appl. Phys. 35 240). The data were analysed considering a power dependence of the a.c. conductivity on frequency σ ac ∝ω n , n ⩽1. It was found t…
Boron carbide nanorods were prepared on a large scale directly from the reaction of carbon nanotubes with boron powder at 1150 °C. The bent carbon nanotubes transform into straight nanorods during the reaction. The atomic ratio of B to C in the nanorods is very close to 4 ∶ 1, corresponding to the compound B4C. Carbon…
We present experimental measurements of sound velocity and absorption in a commercial shaving foam. We observe that both quantities evolve with time as the foam coarsens increasing its mean bubble radius <R>. By varying the acoustic frequency we probe the foam from the large wavelength regime, lambda approximately 150…