Materials Literature
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This paper outlines the issues and methodology involved in the modeling of irradiation growth in Zr and its alloys, emphasizing on the effects of production bias and of anisotropic diffusion of the point defects. Due to the anisotropy of the crystal structure, the usual rate theory model for cubic metals, which assume…
At zero temperature, the elastic constants of diluted central force networks are known to vanish at a concentration ${p}_{r}$ (of either sites or bonds) that is substantially higher than the corresponding geometric percolation concentration ${p}_{c}$. We study such diluted lattices at finite temperatures and show that…
Abstract. Plastic deformation in two-dimensionalmonophase and composite materials is studied using a discrete dislocation dynamics method. In this method, dislocations are represented by line defects in a linear elastic medium, and their interactions with boundaries or second-phase elastic particles are incorporated t…
Deuterium solid-state quadrupole-echo NMR was used to study the effect of molecular weight on the segmental dynamics of bulk and adsorbed poly(methyl acrylate)- d 3 (PMA- d 3 ). It was found that the bulk PMA- d 3 with lower molecular weight was more mobile and more heterogeneous in motion than the high molecular weig…
The hydrogenation of polystyrene-block-polybutadiene-block-poly(ε-caprolactone) SBC triblock copolymers was performed in the presence of the Wilkinson catalyst RhCl(P(C6H5)3)3. Reaction conditions (hydrogen pressure, temperature and reaction time) were varied to ensure quantitative hydrogenation without detectable sid…
It is well known that the physical properties of a polymer alter with time. This phenomenon—ageing—is strongly related to the external factors acting upon the polymer and to the manufacturing process. An appropriate process could prevent the premature and undesired changes in the characteristics of a polymeric materia…
The effects of seed particles and shear rate on the size and shape of α‐Al 2 O 3 particles synthesized in glycothermal conditions are described. It is proposed that seed particles provide a low‐energy, epitaxial surface in solution to lower the overall surface energy contribution to the nucleation barrier, thus increa…
Abstract. The stability of aggregates can be improved by amending the soil with charged synthetic polymers. We have evaluated the effects of addition of low rates of anionic polyacrylamide (PAM) on the stability of aggregates from three predominately kaolinitic soils, and investigated whether the applied PAM penetrate…
A numerical model of first-order phase transformations is presented that considers the mutual blocking of growing particles up to all relevant orders. It is applicable for nucleation and growth problems in any space dimensions, even in the case of highly anisotropic growth. Illustrative Monte Carlo simulations were ca…
Partially sericitized tourmaline from a pegmatite was investigated using high-resolution transmission electron microscopy (HRTEM). Fine-grained muscovite crystals form extensive narrow veinlets preferentially developed along the {110} and {100} cleavages of tourmaline, indicating that a cleavage-controlled alteration…
A new design strategy for enhanced nonlinear optical properties, based on a simple vector model and situated at the mesoscopic level, between the microscopic molecular level and the macroscopic bulk, is explained and exemplified by a number of organic superstructures. The second-order nonlinear optical properties of t…
The dynamic mean-field density functional method is used to describe phase separation including hydrodynamic effects in specific three-dimensional (3D) compressible copolymer liquids. We show that it is justified to use Darcy’s approximation for the velocity field. This simple model enables us to reproduce both the in…
Abstract Although the kinetics of the dehydroxylation of kaolinite have been widely studied, there is no definitive explanation of its mechanism due to its dependence on a variety of parameters. In this study, the dehydroxylation of kaolinite has been studied using controlled-transformation rate thermal analysis (CRTA…
There are two routes in the opening of the pseudogap: one due to the band separation in a disordered system such as expanded liquid mercury and amorphous alloys and the other due to the Fermi surface-Brillouin zone interaction in quasicrystals and their approximants. The role of the pseudogap in the electron transport…
The reactions of LiSi(SiMe3)3 with Cl(Me)2B3N3(Me)3, Cl2(Me)B3N3(Me)3, (ClBNMe)3, and (ClBNH)3 result in the formation of molecular species (Me3Si)3Si(Me)2B3N3(Me)3, [(Me3Si)3Si]2(Me)B3N3(Me)3, [(Me3Si)3SiBNMe]3, and [(Me3-Si)3SiBNH]3. The new compounds have been characterized by spectroscopic techniques, and a single…
In orientationally biased grand canonical ensemble Monte Carlo (GCEMC) simulations we investigated the microscopic structure of liquid-crystalline films confined between two plane parallel solid surfaces (i.e., walls) consisting of Ns discrete, rigidly fixed atoms. These wall atoms are distributed across the plane of…
A technique for producing ceramic preforms with graded porosity via colloidal infiltration of molded polymer sponges has been developed. Polymer sponges have been compression molded into various shapes with continuous and/or stepwise gradients in porosity. Infiltration of the graded sponge with ceramic slurry, followe…
Carbon nanotubes have a whisker-like structure so an extremely high strength and lack of plasticity are generally predicted. In-situ observations made by transmission electron microscopy, however, prove that carbon nanotubes bend plastically at room temperature. The bending process at the atomic level is suggested by…
Mössbauer spectrometry of natural samples of tourmaline shows the presence of Fe 2+ and Fe 3+ either in the Y (9b) or the Z (18c) sites, with intervalent iron delocalized between these sites. To understand the distribution of iron in natural samples, tourmaline was synthesized at temperatures from 400 to 700 °C, unde…
Magnetization and resistivity of CrO2 powders and oriented CrO2 films on different TiO2 single-crystal substrates are reported, and the low-temperature specific heat is measured on powders. The M(T) data follow a Bloch T3/2 law, with no sign of a spin-wave gap. The residual resistivity depends strongly on film texture…