Materials Literature
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Infrared transmission of 25 liquid crystal compounds was evaluated. Based on these results, a liquid crystal mixture consisting of fluoro and dialkyl diphenyl-diacetylene homologs was developed for CO2 laser application. This mixture exhibits a wide nematic range, high birefringence, low viscoelastic coefficient, and…
Ag(111) and Ag(110) surfaces exposed to oxygen at elevated temperatures (\ensuremath{\sim}800 K) exhibit strongly enhanced Raman bands at 803 and 627 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ which are attributed to O atoms strongly chemisorbed on the surface (${\mathrm{O}}_{\ensuremath{\gamma}}$) or held in subsurfa…
A thin bilayer of two coexisting polymer phases, in contact with a surface which favors and is partially wetted by one of them, was studied by nuclear reaction analysis and phase contrast microscopy. We find that when the less-favored phase is initially in contact with this surface, it is entirely replaced by the part…
We report experimental investigation and theoretical interpretation of the formation of sprial waves in a nematic liquid crystal subjected to a rotating magnetic field and a high frequency electrical field.
A unified model of phonon-assisted and zero-phonon radiative transitions in nanoscale silicon structures is presented. For characteristic sizes above 15--20 \AA{}, phonon-assisted transitions dominate, while zero-phonon transitions, allowed due to the finite-size effect, are more important for smaller length scales. L…
An expeditious and accurate simplification of Stone and Scallan's solute exclusion technique was developed, thereby avoiding several sources of experimental error coupled with the determination of cellulose pore volume. Using this method, it is shown that cellulolytic enzymes do not enter into the micropores of five s…
Rhenium heptafluoride, ReF(7), is one of only two stable binary compounds MX(7) with a heptacoordinated metal atom M and halide atom X. Its low-temperature crystal structure, as determined by high-resolution powder neutron diffraction, reveals the molecular structure, which has been the subject of speculation and deba…
Physical inclusion of small molecules in larger structural lattices is well known in the crystalline state and is a common feature of the chemistry of zeolites. In the liquid state, a variety of synthetic macrocyclic molecules are available to complex and contain smaller guest species. An alternative strategy for bind…
How do carbon and silicon chemistry differ? For example, the cyanide⇌isocyanide equilibrium is completely reversed in the sila series. According to calculations silane nitrile ( 2 ) is higher in energy than its isomer 1 , which has been known for much longer. The matrix isolation of 2 has now been achieved; 2 is the f…
Abstract This text, aimed at final-year undergraduate students and new postgraduates in physics, provides a broad introduction to surface physics, covering key areas of surface studies. Techniques are described that are used to determine which atoms are present on a surface and in what quantities, and to determine the…
This is a fully revised and expanded edition of a very successful and widely used book. It describes the physical basis of all the principal, and most of the more specialised, techniques currently employed in the study of well-characterised solid surfaces. The coverage of each technique, illustrated with selected exam…
Abstract Magnets composed of molecular species or polymers and prepared by relatively low‐temperature organic synthetic methodologies are a focus of contemporary materials science research. The anticipated properties of such molecular‐species‐based magnetic materials, particularly in combination with other properties…
The numerical fitting of an analytical function representing electron density profile at a jellium surface to the one tabulated by Lang and Kohn is presented. The two sets of parameters entering the electron density profile is proposed. The first one is obtained by purely numerical fitting, and the second one is calcu…
<div class="htmlview paragraph">The need to reduce the weight of automobiles has favored the widespread use of aluminum in automotive ventilation and cooling systems. Space, weight restrictions, the need for increased thermal efficiency, and recycling legislation have all contributed to new designs for heat exch…
Abstract X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and magnetization (SQUID) data are reported for a “pyrrhotite-like” compound ( δ -FeSe), belonging to the central portion of the Fe-Se system. The δ -phase(s) extends compositionally over a range of around Fe 0.94 Se-Fe 0.86 Se at 870 K, but narrows around…
Effect of high pressure on the crystal structure of rhombohedral NaNO3 was investigated by X-ray diffraction of single crystals mounted in a miniature diamond-anvil cell on synchrotron radiation source. Diffraction intensity measurements were made at three pressures across a suggested transition pressure 4.3 GPa. No c…
High pressure X-ray diffraction study was carried out on a graphite to investigate its compressibility as well as any possible phase transition to the hexagonal diamond structure at room temperature. Energy dispersive X-ray diffraction method was introduced using a Mao-Bell type diamond anvil cell with Synchrotron Rad…
Experimental and observational evidence is reviewed for the mechanisms and kinetics of antiphase domain coarsening in silicate minerals. The expected rate law has the form (domain size)n ≈ annealing time, but the ideal value of n=2 has been observed in only one of three cases. Values of n≈8 or 10 are interpreted as im…
The kinetics of the hydrogen absorption and desorption behaviour of a NdFeB sintered magnet is studied. Hydrogenation at temperatures above 200/spl deg/C is used to crumble the Nd-enriched phase. The grains of Nd/sub 2/Fe/sub 14/B phase remain undamaged. Hydrogen desorption occurs in several stages and is complete at…
Magnetic properties, microstructure and intercrystalline segregation of antimony were examined on 2.4 wt.% Si steels containing 0.005 to 0.047 wt.% Sb. The measured reduction of the total core losses in steels containing 0.040 and 0.047 wt.% Sb has various values for chosen variants of pre-annealing at 500/spl deg/C a…