Materials Literature
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The crystal structures of telyushenkoite, ideally Cs Na6 [Be2 Al3 Si15 O39 F2], trigonal, space group P 3 m 1, a 14.3770(8), c 4.8786(3) A, V 873.2(1) A3, Z = 1, and leifite, ideally Na Na6 [Be2 Al3 Si15 O39 F2], trigonal, space group P 3 m 1, a 14.361(1), c 4.8570(5) A, V 867.5(2) A3, Z = 1, have been refined to R in…
New thermotropic mesomorphic compounds containing a [2.2]paracyclophane (PC) unit were synthesized and investigated (Scheme). Carboxylic acids were selected as the starting PC building blocks. The influence of structural features on the stability of the mesomorphic phases was studied (Figs. 1 and 2): for this purpose,…
Characteristics of an ion beam surface modification system with a linear ion source are described in this article. The linear ion source is principally based on an anode layer thruster, which is generally referred to as “closed drift thruster.” The linear ion source has a slit type racetrack-shape extraction geometry.…
An alkoxide sol–gel route was developed to prepare forsterite fibers. Transparent precursor gel fibers were converted to the crystalline phase of forsterite by heating above 550°C. Fibers heated at 1100°C for 2 h showed a porous microstructure with nanocrystalline sizes of about 50–100 nm. The structural evolution of…
Ruby-red crystals of Ag2Bi2S3Cl2 were synthesized from AgCl and Bi2S3 by cooling a melt from 770 K to room temperature. X-ray diffraction on powders and single-crystals revealed a triclinic crystal structure with special lattice constants (P &1macr; (No. 2), a = 1085.0(2), b = 717.2(1), c = 1137.6(1) pm, α = 89.80(1)?…
An alternative set of Cartesian vector wave functions is presented to simplify the development of eigenfunction expansions of electromagnetic fields and dyadic Green's functions for bianisotropic media. With the eigenfields expanded using these functions, the determination of their expansion coefficients is facil…
The ferroelectric nematic ordering of finite-length hard spherocylinders with longitudinal dipoles is demonstrated in an extended version of the Onsager formalism. The stability analysis as well as numerical simulations were performed to obtain a complete phase diagram for the ferroelectric nematic order in terms of t…
All the essential switchable mirror properties of ${\mathrm{YH}}_{x}$ exhibit a strong hysteresis that is related to the structural \ensuremath{\beta}-dihydride to \ensuremath{\gamma}-trihydride phase transition. This structural transition in ${\mathrm{YH}}_{x}$ has so far been difficult to investigate since polycryst…
Though a tremendous amount of research has recently been devoted to synthesis and characterization of carbon nanotubes, few students have been afforded the opportunity to study these species in a laboratory course setting. As a part of an introductory laboratory course in the Chemical and Materials Physics (ChaMP) gra…
Starting from three powder mixtures of 80 vol% SiC (100α, 50α/50β, 100β) and 20 vol% YAG, liquid‐phase‐sintered silicon carbide ceramics were prepared by hot pressing at 1800°C for 1 h under 25 MPa, and then by hot forging or annealing at 1900°C for 4 h under an applied stress of 25 MPa in argon. The phase transformat…
Eight series of fluorosubstituted three-ring ester liquid crystals have been synthesized. Polarizing microscopic textural observations and DSC measurements of their phase transitions show that most are thermotropic liquid crystals with nematic and smectic A phases; furthermore, several show monotropic high order smect…
Phosphate-containing polyester macroglycols with different phosphate contents were synthesised from a phosphorus-containing monomer, a dicarboxylic acid and a diol. The macroglycols were then used as a soft segment for the preparation of segmented polyurethane dispersions. Aqueous dispersions were made by phase invers…
Abstract A nonlinear dynamic model of a seeded potash alum batch cooling crystallizer is presented. The model of the batch crystallizer is based on the conservation principles of mass, energy and population. In order to maintain constant supersaturation, a nonlinear geometric feedback controller is implemented. It is…
The electronic structure of the Ruddlesden-Popper layered perovskite compound ${\mathrm{Sr}}_{3}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ is studied from density-functional calculations using the linear muffin-tin orbital method. An antiferromagnetic, insulating solution is obtained in agreement with the experiments, with a…
Ultrathin magnetic films are considered where the thickness-induced second order phase transition occurs due to surface magnetic anisotropy changes. By increasing the thickness, the easy magnetization axis state passes through the easy cone state (for film thickness t: t1 < t < t2) into the easy magnetization plane st…
Porphyrin quinones are attractive model compounds for mimicking natural electron transfer processes. While the overwhelming majority of studies have been performed with porphyrin p-quinones the isomeric porphyrin o-quinones have been mostly neglected. Using phenanthrene-9,10-quinones as the acceptor component we have…
Nitramide was investigated by multinuclear NMR spectroscopy, X-ray-diffraction and computational methods. The crystal structure analysis at various temperatures reveals a planar conformation of the molecule with a N-N bond length corresponding to a bond order between one and two. Hydrogen bonds connect the nitramide m…
This article presents experimental results for tensile creep behavior of orthogonal three‐dimensional woven Tyranno™ ZMI fiber/Si‐Ti‐C‐O ceramic matrix composites at 1300°–1450°C in air. The composite contained Tyranno ZMI (56% silicon, 1% zirconium, 34% carbon, and 9% oxygen) fibers with a BN coating layer to improve…
The effect of phosphate ions on the corrosion behaviour of copper in sulphate solutions was investigated at different temperatures (293, 313, 333, and 353 K) and at different pH values (pH = 2·1, 7·2, and 12·3). A three electrode electrochemical technique was used for the measurements, using a saturated calomel electr…
Cordierite-zircon ceramic composites were fabricated by die pressing a commercial cordierite powder with the addition of up to 10 wt-% zircon (ZrSiO4). Sintering of cordierite was enhanced by the ZrSiO4 addition through glass phase formation. With ZrSiO4 additions above 2·5 wt-% no further effect on the mechanical pro…