Materials Literature
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The synthesis of colloidal boehmite (AlOOH) is studied by heating basic aluminum chloride solutions under constant stirring. The temperature and Al 2 O 3 : Cl molar ratio influence the product morphology. Synthesis at 140°C generates highly fibrous polycrystalline particles that are on average 360 nm long, 30 nm broad…
The Daresbury station 8.3 powder diffractometer has been used to determine the lattice parameter of tungsten powder to about 3–6 p.p.m. with respect to the National Institute of Standards and Technology SRM640B silicon de facto standard. The measurement and analysis algorithms that have been developed indicate that th…
It is shown that, in the transitional region between the B and C kinetic regimes for grain-boundary diffusion, the product of the grain-boundary width δ, the segregation factor K and the grain-boundary diffusion coefficient D b= KδD b), as well as the grain-boundary diffusion coefficient itself, can be estimated. From…
X-ray studies on a material whose constituent molecules have a weak transverse dipole moment provide clear evidence of a first-order smectic-A--smectic-C transition. In addition, results on materials belonging to the same homologous series of compounds show that this transition can be driven from second order to first…
Previous data for the pressure dependence of the order parameter for ${\mathrm{BaTiO}}_{3}$ at room temperature (RT) as well as new data for the pressure dependence of the order parameter for ${\mathrm{PbTiO}}_{3}$ at RT have been analyzed within the framework of a phenomenological theory for ferroelectrics. It is con…
A dual purpose pyrometer is described that allows both accurate radiance temperature measurement and fast temporal response. The system uses two silicon photodiodes with separate optical paths derived from a common spot on the sample. The optical bandwidths and response times of each detection circuit are tailored to…
We present a field-theoretic treatment of polymer solution dynamics. The method involves the construction of a Martin–Siggia–Rose generating functional for flexible polymer chains dissolved in a low molecular weight solvent. This formalism is shown to be particularly convenient for investigating the dynamics of collec…
Abstract The three series of polyether polyurethane cationomers based on MDI, HDI, and TDI that are the subject of Part I, undergo emulsification (or phase inversion) on addition of water to solutions in MEK. The phase inversion mechanism depends on the structure of hard segment, ionic content, and dispersion temperat…
Absorption saturation and luminescence measurements on semiconductor-doped glasses are reported, and the results are analyzed in terms of a band-filling model that is found to explain adequately the absorption data obtained with fresh as well as with photodarkened samples. With this model the free-carrier densities ar…
The interaction of hydrogen and deuterium with the (OOO1) surface of beryllium has been investigated using resolution electron energy loss spectroscopy, thermal desorption spectroscopy, and work function measurements. Dissociative adsorption of molecular hydrogen is an activated process, and recombinative desorption o…
The aging behaviour of quenched Zn–Al alloys containing small additions of copper was studied using metallography, hardness measurements, and quantitative X-ray diffraction. The kinetics of decomposition of supersaturated α/α′ and β phases were determined and related to structural changes. It was found that the Avrami…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNeutron reflectivity study of block copolymers adsorbed from solutionS. K. Satija, C. F. Majkrzak, Thomas P. Russell, S. K. Sinha, E. B. Sirota, and G. J. HughesCite this: Macromolecules 1990, 23, 16, 3860–3864Publication Date (Print):August 1, 1990Publication History Publis…
Defect creation in 24% densified, high-OH-concentration amorphous ${\mathrm{SiO}}_{2}$ has been studied using 248-nm excimer laser radiation. Combining laser and \ensuremath{\gamma}-ray radiation data, we find correlated growth of oxygen-vacancy and nonbridging oxygen-hole-center defects over a range of concentration…
With short Au…︁Au contacts of 2.9 Å, the “dimeric” structure of the polymeric [AuSe5]⊖ anion 1 in KAuSe5 provides a further example of d10–d10 interactions in the solid state. KAuSe5 is formed as reddish-brown, needlelike crystals from a polychalcogenide melt (K2Se: Au:Se = 2:1 :8); if the amount of K2Se is reduced to…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new mechanism of toughening glassy polymers. 1. Experimental proceduresO. S. Gebizlioglu, H. W. Beckham, Ali S. Argon, R. E. Cohen, and H. R. BrownCite this: Macromolecules 1990, 23, 17, 3968–3974Publication Date (Print):August 1, 1990Publication History Published online1…
An automatic diffraction data collection system with an imaging plate has been developed for protein crystallography. The system works in a similar way to the conventional rotation camera method, but in full online mode. After exposure to the X-ray beam, the imaging plate (100 mm radius) rotates whilst a reading head…
The limitations and advantages of particular dyes for labelling proteins and other biological materials are discussed. Methods available for conjugating dyes to proteins are outlined. Following a discussion of double labelling methods the use of photoactivatable fluorochromes and time resolved fluorescence methodologi…
A correlation is observed between the ESR spectra (at 1.12 GHz) and the magnetization inversions of the spin glass AgMn for a Mn concentration of 8.3 at. %. This is because of rearrangement of the spin system during the magnetization inversions. The widths of the ESR lines W↑ und W↓ which correlate, respectively, with…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure, magnetism, and electronic and EPR spectroscopies of bis(2-aminopyrimidinium) tetrachlorocuprate(II): a square-planar CuCl42- anion with semicoordinated cationic ligandsClaudia Zanchini and Roger D. WillettCite this: Inorg. Chem. 1990, 29, 16, 3027–3030Publ…
Abstract The electrical conductivity (σ) and thermoelectric power ( Q ) of polycrystalline lithiumcadmium ferrites having the chemical formula Li 0.5– x /2 Cd x Fe 2.5– x /2 O 4 where ( x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) have been investigated as a function of temperature. Lithium‐cadmium ferrite with x = 0.4 is fo…