The crystal chemistry of the eudialyte group
Mineralogi
Materials Literature
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Vibrational analysis of the dioctahedral mica; 2M 1 muscovite
Raman spectra and lattice dynamics calculations are presented for the dioctahedral mica, muscovite. Calculated fundamental mode frequencies for the Raman-active and A g and B g species were fit to observed fundamentals assigned to features in the two polarized Raman spectra collected, so that unambiguous vibrational a…
A decagonal quasicrystal with a Griffith crack
The crack theory in conventional linear elasticity fracture mechanics is extended to quasicrystal linear elasticity fracture mechanics. A decagonal quasicrystal containing a Griffith crack penetrating through the solid along the period direction is considered. By means of a general solution, the analytical expressions…
Raman characterization of germanium nanocrystals in amorphous silicon oxide films synthesized by rapid thermal annealing
Raman characterization of germanium (Ge) nanocrystals embedded in amorphous silicon oxide (a-SiO2) films synthesized by rapid thermal annealing (RTA) has been carried out. The samples were prepared by cosputtering Ge and SiO2 targets using a rf magnetron sputtering machine. Ge nanocrystals can only be obtained from sa…
The Water Activities of MgCl2, Mg(NO3)2, MgSO4, and Their Mixtures
The water activities of aqueous MgCl 2, Mg(NO3)2, and MgSO solutions and their mixtures - MgCl 2-Mg(NO3)2 (mole ratio 3:1, 1:1, 1:3), MgCl 2-MgSO4 (1:1), Mg(NO3)2-MgSO4 (1:1), and MgCl 2-Mg(NO3)2-MgSO4 (1:1:1 and 1:1:5) - were measured at room temperature from dilute solution to high supersaturation using an electrody…
Oxygen adsorption on Ag(111): X-ray photoelectron spectroscopy (XPS), angular dependent x-ray photoelectron spectroscopy (ADXPS) and temperature-programmed desorption (TPD) studies
The O2 adsorption on Ag(111) single crystal in the range of 300–500 K has been studied by XPS, ADXPS, and TPD. At room temperature, the O1s line observed at 530.0 eV goes down to 528.2 eV when the sample is heated to 420 K. The comparison of XPS and TPD data indicates that both lines can be assigned to chemisorbed ato…
Voltammetry Studies of Single‐Crystal and Polycrystalline Diamond Electrodes
Boron‐doped polycrystalline and near‐single‐crystal quality diamond electrodes were studied by voltammetry. A redox couple with vs. standard hydrogen electrode was detected on the polycrystalline electrodes but was absent on the single‐crystal electrodes. The results strongly suggest that the couple is associated with…
Surface characterization and adsorption abilities of cellulose fibers
Abstract The adsorption abilites of cotton cellulose fibers are very often modified by alkaline treatments in form of alkaline purification or mercerization using high concentration of NaOH. We tried to determine the correlation between morphological modifications and the adsorption abilities of cotton fibers using se…
Effect of cyclic moisture absorption desorption on the mechanical properties of silanized jute‐epoxy composites
Abstract The goal of this paper is to discuss the influence of water absorption‐desorption cycles on the mechanical properties of natural fiber reinforced plastics. Therefore, epoxy resins with jute wovens as reinforcement with untreated and silane treated fibers were investigated. Silane treatment of fibers led to in…
Structural development in the early stages of annealing of sol–gel prepared lead zirconate titanate thin films
Lead zirconate titanate (PZT) thin films on platinized silicon were fabricated and their structural development upon annealing was characterized by x-ray diffraction and transmission electron microscopy (TEM). The amount of a transient intermetallic phase Pt3Pb was found initially to increase with annealing time and t…
Silicon nitride coating on titanium to enable titanium-ceramic bonding
Failures that occur in titanium-ceramic restorations are of concern to clinicians. The formation of poorly adhering oxide on titanium at dental porcelain sintering temperatures causes adherence problems between titanium and porcelain, which is the main limiting factor in the fabrication of titanium-ceramic restoration…
Low‐Temperature Pressureless Sintering of alpha‐SiC with Al 4 C 3 ‐B 4 C‐C Additions
Various combinations of Al 4 C 3 , B 4 C, and carbon were used as sintering aids for pressureless sintering of alpha‐SiC (94% 6 H + 6% 15 R ) powders. Densification behavior, polytypic transformation, microstructural development, and mechanical properties were studied. Appropriate amounts of Al 4 C 3 ‐B 4 C‐C addition…
Comparison and Assessment of Electron Cross Sections for Monte Carlo Track Structure Codes
The purpose of this study was to make an intercomparison and assessment of cross sections for electrons in water used in electron track structure codes. This study is intended to shed light on the extent to which the differences between the input data and physical and chemical assumptions influence the outcome in biop…
A New Approach to Compositional Limits for Sepiolite and Palygorskite
Abstract Most bulk chemical analyses of sepiolite and palygorskite available in the literature are erroneous because samples analyzed are admixtures of minerals that are difficult to separate or identify by other techniques. Some chemical analyses performed on selected individual particles by energy dispersive X-ray a…
Fourier modelling of the anisotropic line broadening of X-ray diffraction profiles due to line and plane lattice defects
A new model of line-profile broadening due to the effect of linear and planar lattice defects has been incorporated into the conventional Rietveld algorithm for the structural refinement and whole-pattern fitting of powder data. The proposed procedure, applied to face-centred cubic (f.c.c.) structure materials, permit…
Biaxial torus around nematic point defects
We study the biaxial structure of both line and point defects in a nematic liquid crystal confined within a capillary tube whose lateral boundary enforces homeotropic anchoring. According to Landau-de Gennes theory the local order in the material is described by a second-order tensor Q, which encompasses both uniaxial…
On the nature of grain boundaries in the colossal magnetoresistance manganites
The electrical transport properties of grain boundaries in the epitaxial La 2/3 Ca 1/3 MnO 3 − δ thin films have been studied as a function of temperature and applied magnetic field. Below the Curie temperature T C an additional grain boundary resistance, highly non-linear current-voltage curves, and a large magnetore…
6-Oxychitins, novel hyaluronan-like regiospecifically carboxylated chitins
Crustacean chitins and fungal chitin–glucan complexes are subjected to regiospecific oxidation at C-6 with NaOCl in the presence of Tempo® and NaBr at 25°C in aqueous solution. The resulting products have anionic character and are fully soluble over the entire pH range; they lend themselves to metal chelation, polyele…
Evidence for 6‐Coordinated Zirconium in Inactive Nuclear Waste Glasses
In inactive glasses used as models for French nuclear waste forms, Zr K ‐ and L 2,3 ‐edge X‐ray absorption spectroscopy spectra indicate that Zr is only 6‐coordinated, with d (Zr‐O) distances of 2.08 ± 0.01 Å and with a small radial disorder. Beyond, the first coordination shell, next‐nearest Si neighbors occur at abo…
Localized spin canting in partially invertedZnFe2O4fine powders
Stoichiometric zinc ferrite fine powders showing long-range magnetic order to temperatures above 30 K have been prepared by the supercritical sol-gel method. The low-temperature magnetic behavior of the as-produced powder, and portions calcined at 500 and 800 \ifmmode^\circ\else\textdegree\fi{}C, were determined by M\…