Materials Literature
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A viscoplastic self-consistent (VPSC) multiscale model for predicting the plastic behaviour of materials with lamellar microstructures is presented. In this approach, three different scales are defined: the microscopic, at single crystal (single lamella) scale; the mesoscopic, at the scale of a single lamellar colony…
The glass transition temperatures Tg of butyl acrylate–methyl methacrylate copolymers obtained by free radical polymerization in 3 and 5 mol/L benzene solution have been measured using differential scanning calorimetry (DSC) and the values have been correlated using Johnston's equation with inter-intramolecular copoly…
The polarized Raman spectra of La0.7Ca0.3MnO3 magnetoresistive thin films deposited on LaAlO3, SrTiO3, YSZ, and MgO substrates were studied in a broad temperature range including Tc. Depending on variations of their intensity and linewidth upon cooling, the Raman bands could be classified into two groups. The lines co…
Novel water-soluble polyesters with pendant carboxylic groups were synthesized by polycondensation of ethylenediaminetetra-acetic acid (EDTA) dianhydride and diethylenetriaminepenta-acetic acid (DTPA) dianhydride with poly(ethylene glycol)s of different chain-lengths. Two experimental approaches (polycondensation usin…
Abstract Polymers possess a very large inherent capacity for property modifications. The bridge between structure or morphology and mechanical properties is created by the micromechanical processes of deformation and fracture, the “micromechanics.” Developments mainly in electron microscopy (EM) (scanning, transmissio…
The light-induced reorientation of nematic liquid crystals is discussed with special emphasis on the effect of dye-dopants. A molecular model is presented which accounts for the large increase of the optical torque, observed in absorbing nematics. An analogous process is described for dye-doped isotropic liquids and t…
We investigate the formation of a two-dimensional quasicrystal in a monodisperse system, using molecular dynamics simulations of hard-sphere particles interacting via a two-dimensional square-well potential. We find that more than one stable crystalline phase can form for certain values of the square-well parameters.…
At the macroscopic scale two different phenomena illustrate the couplings between the elastic and magnetic behaviours of ferromagnetic materials: first, magnetisation induces a deformation mechanism called magnetostriction, and, second stresses have an effect on the magnetic behaviour. The complexity of the non-linear…
A detailed survey is given of the models devised to describe the kinetics of charge movement, both electronic and ionic, through thin-film tungsten trioxide WO3 during either reduction or oxidation. The principal models are those of Faughnan and Crandall, Green, Ingram Duffy and Monk, and of Bohnke. Adjuncts and adapt…
Low-temperature sintering of (Pb 0.86 Ba 0.04 Sr 0.12 )(Zr 0.56 Ti 0.44 Sb 0.02 )O 3 (PBSZT) powders was investigated using Pb 5 Ge 3 O 11 (PGO) or LiBiO 2 (LBiO) as sintering aids. 1 wt% PGO or 1 wt% LBiO-added PBSZT powders could be densified into sintered bodies at 800°C for 2 h with a relative density of approxima…
We have investigated the dependence of the mechanoluminescence intensity from Sr3Al2O6: Eu on compressive stress. The distribution of the mechanoluminescence intensity, which is clearly visible to the naked eye, is consistent with the calculated stress distribution. The luminescence centre has been identified as the E…
We shall discuss our recent high pressure Raman studies on single wall carbon nanotube (SWNT) bundles and compare them with pressure-induced amorphous and polymeric phases of crystalline C60 and C70. Our high pressure Raman studies on SWNT bundles carried out upto 25.9 GPa show that the intensities of both the radial…
Carbonates are one of the most important group of minerals that fix phosphates in soils. Magnesium and silicon are known to reduce the P fixation of calcite. The effect of Mg and Si addition on P sorption–desorption of a mixture of 90% clay and 10% calcite was studied. The mixtures were montmorillonite–calcite (Mont–C…
Single-wall carbon nanotubes, seamless cylindrical molecules formed from a graphene sheet, are either conducting or semiconducting, depending on the particular "wrapping vector" that defines the waist of the tube. Scanning tunneling microscopy experiments have tested this idea by simultaneously measuring a tube's latt…
Amorphous boron-carbon-nitrogen (BCN) powders were produced by mechanically milling a mixture of hexagonal boron nitride (h-BN) and graphite powders for 120 h in an argon atmosphere. By annealing the amorphous BCN powders isothermally under 4 GPa at temperatures above 880 K, a new B–C–N crystal with a tetragonal struc…
We propose a POS (Piezo on Silicon) actuator, which comprise piezoelectric materials on a silicon substrate, and the actuation mechanism uses a bending vibration of a unimorph structure. Realization of this device was attempted, and the low-temperature sintering of piezoelectric ceramics, optimization of the screen-pr…
Results from the literature and unpublished ones of the present authors are summarized which are relevant to the mechanisms governing the mobility of dislocations in icosahedral Al-Pd-Mn quasicrystals. These results concern macroscopic deformation tests, conventional transmission electron microscopy, in situ straining…
Polypropylene/CaCO3 composites were homogenized in a twin-screw compounder and then injection molded into tensile bars. Six different fillers were used in a wide range of average particle sizes between 0.08 and 12 μm. Tensile and flexural properties were measured by standard techniques, while impact resistance was det…
In body centred cubic (bcc) crystals at low temperatures, the thermally activated motion of screw dislocations by the kink-pair mechanism governs the yield properties and also affects the strain hardening properties. In this work, the average strength of dislocation junctions is derived and numerically estimated in th…
The introduction of rubbery particles can be applied to enhance shear yielding and, consequently, the toughness of brittle amorphous polymers. The critical transition in these polymers from crazing to shear yielding requires a submicrometer- or even nanometer-sized rubbery phase. These can be obtained via coalescence…