Materials Literature
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Dimeric biphenyl liquid crystals with trisiloxane containing spacers were studied. Both the tail lengths and the spacer lengths to a central hexamethyltrisiloxane group were varied. In most cases a SmC-phase was found with an anticlinic interlayer relation. One of the compounds appears to have a SmA-phase, which could…
A survey of computer programs for powder diffraction is presented. For each program a brief description of its use, a primary reference and a URL or contact e-mail address that should enable the reader to get easy access to the required software are given.
We demonstrate the microwave detection effect in a granular La0.7Ca0.3MnO3 sample. Dc voltage generated by the sample in response to microwave irradiation below the Curie temperature is found to be dependent on the applied magnetic field. The magnetic field dependence of the dc voltage has a broad peak resembling an a…
This chapter gives an overview of the types of information available from powder diffraction as well as explaining the fundamental origins of the features containing that information.
The history and features of the crystallographic databases [the Powder Diffraction File (PDF), the Cambridge Structural Database (CSD), the Inorganic Crystal Structure Database (ICSD), Pearson's Crystal Data (PCD), CRYSTMET, the Protein Data Bank (PDB) and the Crystallography Open Database (COD)] that are useful for p…
We have investigated Focal Conic Domains (FCD) in several materials that have a transition from a SmA to a nematic phase (N): the focal lines are seldom an ideal ellipse and an ideal hyperbola, and suffer large transformations (in shape and in size) when approaching the transition to the nematic phase, or appear imper…
A thermoreversible (physical) gel of a nematic liquid crystal in its planar configuration is investigated. The transition temperatures of the gel are thermally and rheologically determined. The temperature for the nematic-isotropic transition is higher than that for the gel-sol transition, allowing the network to grow…
The methods for studying nanometre-scale structure in materials from powder diffraction data are often referred to as `total scattering' or atomic pair distribution function (PDF) analysis. This chapter aims to present the background theory in a rigorous but intuitive way. Different approaches to modelling the data ar…
Electron-stimulated reactions in thin [<3 ML (monolayer)] water films adsorbed on TiO(2)(110) are investigated. Irradiation with 100 eV electrons results in electron-stimulated dissociation and electron-stimulated desorption (ESD) of adsorbed water molecules. The molecular water ESD yield increases linearly with water…
A low-cost computer-based tensile testing apparatus is described that allows a graphical display of force–extension curves during the stretching of specimens in real time. The experiment is based on a graphics tablet combined with a force sensor. It can be used in a material science laboratory to investigate elastic a…
The paper reports on the effect of substituting Mn for Fe on the magnetostrictive and related properties of Fe 81− x Mn x Ga 19 alloys. Samples of composition were prepared in polycrystalline form and were all single phase BCC. It is shown that the magnetostriction observed in Fe 81 Ga 19 can be enhanced up to about 1…
Mesoporous silica with squared one-dimensional channels (KSW-2-type mesoporous silica), possessing a molecularly ordered framework arising from a starting layered polysilicate kanemite, was obtained through silylation of a surfactant (hexadecyltrimethylammonium, C16TMA)-containing mesostructured precursor with octoxyt…
We use molecular dynamics simulations to study the stabilization of the hexameric, cagelike silicate with double three-ring structure in aqueous and methanolic solutions. We find that in purely aqueous environments its stabilization requires the presence of both tetramethylammonium and tetraethylammonium (TEA) cations…
Achromatic phase retarders based on subwavelength dielectric diffraction gratings are studied numerically in total-internal-reflection configuration in both the visible and near-infrared regions. Rigorous diffraction theory is used to show that the examined gratings, with reasonable fabrication parameters, can act as…
The dielectric anisotropy of liquid crystals causes director reorientation in an applied electric field and is thus at the heart of electro-optic applications of these materials. The components of the dielectric tensor are frequency dependent. Until recently, this frequency dependence was not accounted for in a descri…
Small angle neutron scattering and electron microscopy are used to investigate the ordering of soft latex particles which have been dispersed in water and then brought into contact through evaporation of the solvent. We observe a succession of metastable states where the particles are kept separated by their hydrophil…
This chapter provides a comprehensive overview of the maximum-entropy method (MEM) as it is applied to X-ray powder-diffraction data for computation of an unbiased electron-density map. The MEM requires a strictly positive electron-density map that is described by its values on a fine grid over the unit cell (with gri…
The existence of ponderomotive acceleration effects in the metal bulk has been experimentally demonstrated in the context of the femtosecond plasmon-assisted multiphoton photoelectric effect in metal systems. The resulting electron energy spectra show that these effects essentially depend on the coupling between the s…
Two approaches are available for the analysis of the size and size distribution of the domains in a crystalline powder: pattern decomposition (or fitting) and pattern modelling. In the first case, the information is obtained from some fitting parameter and no direct connection exists between the model and the data; in…
Results describing the interaction of a single sulfur atom with cationic gold clusters (Au(n) (+), n=1-8) using density functional theory are described. Stability of these clusters is studied through their binding energies, second order differences in the total energies, fragmentation behavior, and atom attachment ene…