Electrochemical Emission during Discontinuous Creep of Aluminum‒Magnesium Alloy

Crystallography Reports - It is experimentally established that the discontinuous creep of aluminum?magnesium alloy AlMg6, deformed in an aqueous medium, is accompanied by discrete...     

Melt‒Solution Synthesis and Magnetic Properties of SmFe2.8Sc0.2(BO3)4 Ferroborate

Crystallography Reports - Single crystals of SmFe2.8Sc0.2(BO3)4 ferroborates are grown in melt?solutions based on bismuth trimolybdate. The magnetic properties of grown single crystals are...     

Mesomorphism dependence on molecular rigidity with reference to ‒CH˭CH‒ unit of central bridge

A novel ester homologous series of rich mesomorphism and low temperatures with unexpected phase behaviors of eleven homologues was synthesized and studied with a view to understanding and establishing the relation between mesomorphic behaviour and the molecular structure of a series 4-(4′-n-alkoxybenzoyloxy)-4″-chlorobenzyl cinnamates. All the members of the novel series are enantiotropically smectogenic and the octyloxy (C₈) to hexadecyloxy (C₁₆) homologues are enantiotropically nematogenic, in addition to smectogenic. Odd–even effect is observed for Sm?I/Sm?N transition curve but it is absent for N?I transition curve. Textures of nematic phase are threaded or Schlieren and that of the smectic phase are fan shaped or batonates of smectic-A type phase or Smectic-C type for C₁₆ homologues as judged directly from a heating stage of an optical polarizing microscopy. Analytical and spectral data confirmed the molecular structures of novel homologues. Mesomorphic properties of present series are compared with the structurally similar other known series. The average smectic and nematic thermal stabilities are 92.78°C and 100.8°C, respectively. Mesophase length minimum to maximum for smectic and nematic are 21.0°C to 31.1°C and 8.4°C to 42.6°C respectively. Thus, the present novel series is partly nematogenic and fully smectogenic with considerable degree of mesomorphism and low melting type.     

Synthesis,characterization, and mesomorphic investigation of vinyl ester-substituted chalcones and effect of lateral ‒NO2 and ‒OCH3 group

A novel homologous series of α-4-(4′-n-alkoxy cinnamoyloxy) phenyl β-2″-nitro, 3″–4″ di methoxy benzoyl ethylenes, H_2n+1CnO?C₆H₄?CH?CH?COO?C₆H₄?CO?CH?CH?C₆H₂(NO₂) (OCH₃)₂ (n = 1–8, 10, 12, 14, 16, 18) has been synthesized. All these compounds have been characterized by suitable spectroscopic techniques. C₁ homologue is nonmesogenic, while C₂ homologue shows enantiotropic nematogenic property and the rest of the homologous (C₃?C₁₈) displayed enantiotropically smectogenic plus nematogenic phase. Phase transition temperatures and textures of the LC phase were determined by an optical polarizing microscopy (POM) equipped with a heating stage. The mesomorphic properties of these compounds were confirmed by differential scanning calorimetry (DSC) analysis.     

Production of complex rubidium and cesium hydrogen sulfate‒phosphates

The solubility in the CsH₂PO₄?CsHSO₄?H₂O system at different temperatures (25, 50, and 75°C) is studied and the phase equilibria in the Rb₃H(SO₄)₂?RbH₂PO₄?H₂O system under isothermal conditions (at 25°C) are analyzed. The temperature and concentration conditions for forming Rb₂(HSO₄)(H₂PO₄), Rb₄(HSO₄)₃(H₂PO₄), Cs₄(HSO₄)₃(H₂PO₄), Cs₃(HSO₄)₂(H₂PO₄), Cs₂(HSO₄)(H₂PO₄), and Cs₆H(HSO₄)₃(H₂PO₄)₄ compounds (the latter has been obtained for the first time) are determined. The conditions for growing large single crystals of complex acid rubidium and cesium salts are found.     

Electron microscopy study of the microstructure of Ni–W substrate surface

The surface microstructure of Ni–W alloy tapes, which are used as substrates to form films of high-temperature superconductors and photovoltaic devices, has been studied. Several samples of a Ni₉₅W₅ tape (Evico) annealed under different conditions were analyzed using scanning electron microscopy, energy-dispersive X-ray microanalysis, electron diffraction, and electron energy-loss spectroscopy. NiWO₄ precipitates are found on the surface of annealed samples. The growth of precipitates at a temperature of 950°С is accompanied by the formation of pores on the surface or under an oxide film. Depressions with a wedge-shaped profile are found at the grain boundaries. Annealing in a reducing atmosphere using a specially prepared chamber allows one to form a surface free of nickel tungstate precipitates.     

Electron effects of the substituents on the structure of 4,4′-dipyridylium dications

The crystal structure of N,N′-di(2-hydroxyethyl)-4,4′-dipyridylium diperchlorate C₁₄H₁₈Cl₂N₂O₁₀ is determined by X-ray diffraction at 293 K. The crystals are monoclinic, a = 6.446(1) Å, b = 14.479(3) Å, c = 9.912(1) Å, β = 99.24(2)°, space group P2₁/c, and Z = 2; 1562 reflections measured; and wR2 = 0.086 and R1 = 0.033 for 1209 reflections with F > 4σ(F). It is found that, in the absence of charge transfer from the counterion to the dication, the planarity of the dipyridylium skeleton of the molecule is primarily due to the conjugation between the lone electron pairs of the hydroxyl groups and the π system of the dication. This inference is supported by the intramolecular O?N contact (2.847 Å).     

Mechanical Properties of СeF3 Single Crystals

Crystallography Reports - The anisotropy of the mechanical characteristics of CeF3 crystals (sp. gr. $$P\bar {3}c1$$) grown from the melt by the Bridgman technique has been studied for the first...     

What is the Shape of a Polymer Chain near the Theta Point?

We address the question of the conformation of a polymer near the θ point. To this end, we present an argument that the statistics of polymer rings at the θ point in two dimensions is exactly given by the statistics of the external perimeter (“hull”) of a percolation cluster. As a consequence, the fractal dimension d_f (θ) of a polymer chain at the θ point coincides with that of the hull of the percolating cluster, d_f (θ) - d_H . We also perform extensive simulations of the conventional θ point model—the interacting self-avoiding walk (ISAW)—and the smart kinetic walk (SKW). We demonstrate that the SKW predicts a higher order critical point, termed the θ′ point, which has the same critical behavior as the ISA W. We conclude that the SKW is a well-defined walk that gives the conformation of a polymer near the θ point in two dimensions. In particular, we report accurate calculations of all three tricritical point exponents that are needed to fully describe the θ point.     

Mechanical Properties of Diamond-Like Silicon–Carbon Films Doped with Vanadium

Crystallography Reports - The influence of doping with vanadium on the mechanical properties of nanocomposite films deposited on silicon substrates has been investigated. It is found that the...     

Growth from Solutions,Structure, and Spectral–Luminescent Properties of Crystalline Films of Di-n-hexyl-para-quaterphenyl

Crystallography Reports - The results of studying the growth and structure of crystalline films of para-quaterphenyl derivative with terminal n-hexyl...     

Mössbauer Probe Diagnostics of the Properties of Quasi-Liquid Water Layer on the Aluminosilicate Surface of Natural Origin

Crystallography Reports - The structure and properties of the quasi-liquid water layer in the “frozen water–clay mineral” system have been studied using a probe technique...     

Synthesis and Some Properties of 3-Fluoro-4-Cyanophenyl 4′-n-alkylbenzoates

A series of 3-fluoro-4-cyanophenyl 4′-n-alkylbenzoates, which show monotropic nematic phases, was prepared and their transition temperatures and melting enthalpies were measured. The 3-fluoro-4-cyanophenyl 4′-n-propylbenzoate, 3-chloro-4-cyanophenyl 4′-n-propylbenzoate and 4-cyanophenyl 4′-n-propylbenzoate were mixed with a nematic mixture (A) of 4-n-alkoxyphenyl 4′-n-alkylcyclohexane-1′-carboxylates. 3-Fluoro-4-cyanophenyl 4′-n-propylbenzoate decreases the N-1 transition temperature less, increases the birefringence more, and increases the bulk viscosity less than 3-chloro-4-cyanophenyl 4′-n-propylbenzoate, and reduces the threshold voltage to the greatest extent. The dielectric anisotropies of 3-fluoro-4-cyanophenyl 4′-n-propylbenzoate and 4-cyanophenyl 4′-n-propylbenzoate determined from a series of solutions of the compounds in nematic mixture (A) are 35.9 and 29.6, respectively.     

Peculiarities of the Electron Structure of Pseudobinary Alloys (GeTe)m–(Sb2Te3)n

Crystallography Reports - The electron band structure of GeTe, Sb2Te3, GeSb2Te4, and Ge2Sb2Te5 compounds has been calculated by the electron density functional method using the WIEN2k software...     

Synthesis of Sulfonated Cholesterol Derivatives—Electrical,Thermal, and Optical Properties

Poly(cholesterylacrylatesulfone) (PCHAS) and poly(cholesterylacrylatesulfone-co-1-hexene)s (PCHASHs) at different ratios are synthesized from the monomer cholesteryl acrylate. The liquid crystalline phases are observed under a hot stage fitted with a polarizing optical microscope. The polysulfone and copolysulfones are characterized by FT-IR, ¹H-NMR, DSC, and TGA techniques. From SEM (EDX) the qualitative amounts of elemental sulfur found in PCHAS and PCHASH11 are 2.90 weights (%) and 4.39 weights (%), respectively. The GPC data using THF as the solvent shows that the number average molecular weight of the PCHAS is 5268 g/mol and the molecular weights of the PCHASHs are higher than the PCHAS.     

Dynamical Properties of a Disordered Crystal: Adamantane—C10D16

Inelastic neutron scattering measurements on C₁₀D₁₆ show the existence of underdamped collective librational modes with temperature-independent frequency widths.

A preliminary dynamical model, with no adjustable parameters, shows that the observed widths are consistent with the existing quasi-static disorder.

Direct measurements of the orientational pair correlation function by means of elastic neutron scattering agree with the prediction of a simple Ising model.

Intensity measurements between room-temperature and the ordering temperature (T _c = 208.6K) indicate that the orientational correlations develop very slowly as T → T _c.     

Synthesis and Luminescence Properties of Red Phosphor SrCeO3∶ Sm3 +

采用溶胶-凝胶法合成了SrCeO3∶Sm3+红色荧光粉,用XRD、SEM、FL分析表征了样品的结构、形貌及发光性能.研究了助熔剂H3BO3对其发光性能的影响.结果表明:样品为具有正交晶系结构的SrCeO3晶型,呈椭球型结构.荧光光谱测试结果表明:Sm3+掺杂的SrCeO3在紫外波段有两个吸收带,一是峰值位于320 nm左右的宽吸收带,归属于Ce4+→O2-的电荷迁移带,另一个为峰值位于408nm的锐线吸收带,对应于Sm3+的6H5/2→L13/2跃迁吸收;在波长408nm的激发下,样品发红光,发射主峰位于601nm,对应于Sm3+的4G/2 →6H7/2跃迁.样品的发光强度随着Sm3+和助熔剂H3BO3加入量的增加先增强,后减弱.当Sm3+的掺杂最为3mol％,H3 BO3加入量为0.5 mol％时,发光强度最大.     

New Data on the Isomorphism in Eudialyte-Group Minerals. V: Crystal Structure of an Intermediate Member of the Manganoeudialyte‒Ilyukhinite Isomorphous Series

Crystallography Reports - The crystal structure of a high-symmetry representative of the eudialyte group from the Norra Kärr massif (Sweden) has been investigated by X-ray diffraction analysis...