Synthesis,spectral and thermal characterization of Bis(diethylammonium) tetrachloromercurate(II)-An nonlinear optical material

A new semiorganic compound, bis(diethylammonium) tetrachloromercurate(II) was grown by slow evaporation solution growth technique at ambient temperature from its aqueous solution. The crystal system and the cell parameters have been identified from the powder X-ray diffraction pattern. The UV–visible absorption of the compound shows absorption at 246 nm and there is absorption observed in the entire visible region indicates that the compound can be used as a nonlinear optical material. The UV–visible transmittance spectrum of grown crystal shows a lower cut-off wavelength at 275 nm and it was found that the crystal is suitable for optoelectronic applications. Thermal studies were carried out to find out the thermal stability and confirm the stoichiometric ratio of the compound. The thermal anomalies in DSC study indicate the occurrence of first order transition in the compound at low temperatures. The FTIR spectrum of the compound characterizes various functional groups. The various kinds of protons and carbons were assigned through NMR (¹H and ¹³C) spectroscopic techniques. The SHG efficiency of the compound was studied by Kurtz-Perry power technique and observed that it has SHG efficiency 1.5 times greater than that of potassium dihydrogen phosphate (KDP). The dielectric constant and dielectric loss of the compound decreases with increase in frequency.     

Magnetic and electromagnetic properties of RuZn and RuCo substituted BaFe12O19

Polycrystalline samples of M-type hexaferrites BaFe_12−2xRu_xZn_xO₁₉ and BaFe_12−2xRu_xCo_xO₁₉ with 0x0.45 have been prepared by a classical sintering method. The evolutions with x of the cell parameters, the saturation magnetization and the magnetic transition temperature have been measured; in this range of small doping ratios, saturation magnetization and Curie temperature of substituted hexaferrites remain close to those of the undoped BaFe₁₂O₁₉. X-ray diffraction measurements on oriented powders show that a change of magnetocrystalline anisotropy from axial to planar occurs in both cases for a small substituting ratio x_c=0.375. Microwave electromagnetic characteristics have been studied on the ceramic samples from 0.1 to 10 GHz. The behaviour of the magnetic losses (μ″) corroborates the anisotropy change when doping; a convolution of the dissipation mechanisms (domain wall motions and gyromagnetism) is obtained for x_c. The level of the magnetic losses is discussed in relation with others substituted Ba-hexaferrites.     

On the spectral function of the Poisson–Voronoi cells

Denote by (t)=∑_n1e^−λ_nt, t>0, the spectral function related to the Dirichlet Laplacian for the typical cell of a standard Poisson–Voronoi tessellation in . We show that the expectation E(t), t>0, is a functional of the convex hull of a standard d-dimensional Brownian bridge. This enables us to study the asymptotic behaviour of E(t), when t→0⁺,+∞. In particular, we prove that the law of the first eigenvalue λ₁ of satisfies the asymptotic relation lnP{λ₁t}−2^dω_dj_(d−2)/2^d·t^−d/2 when t→0⁺, where ω_d and j_(d−2)/2 are respectively the Lebesgue measure of the unit ball in and the first zero of the Bessel function J_(d−2)/2.     

柔韧性羧端基不饱和聚酯粉末涂料的研制

本文研制了粉末涂料用柔韧性羧端基不饱和聚酯树脂及其相应的环氧树脂固化的柔韧性不饱和聚酯粉末涂料，讨论了树脂合成，涂料制备及涂层性能，涂层的装饰性能特别是柔韧性能有了较大改善。     

自旋3/2粉末样品四极核中心跃迁的NMR回波序列

本文提出脉冲序列45_X~°—t_1—90_(±Y)~°—t_2,从理论和实验上证实了它能够有效地会聚粉末样品中I=3/2四极核中心跃迁的磁化矢量,并对该回波序列的激发谱宽作了数值计算。     

单道扫描式ICP—AES法测定婴儿乳粉,代乳粉中K,Na,Ca,Mg,P,Fe,Zn,Cu,Mn和Sr

本文采用HNO_3-HClO_4湿法消解样品,用乳化剂OP解决雾化器堵塞问题,利用单道扫描式ICP-AES仪测定婴儿乳粉、代乳粉中十种元素(K、Na、Ca、Mg、F、Fe、Zn、Cu、Mn和Sr)。方法简便快速,回收率在90-105%,相对标准偏差均小于10%,适用于婴儿乳粉、代乳粉中上述元素的测定。     

Sodium dithiophosphate(V): Crystal structure, sodium ionic conductivity and dismutation

Na₃PO₂S₂ was synthesized from the corresponding undecahydrate by freeze–drying. It dismutates at temperatures above 350 °C into Na₃PO₃S and Na₃POS₃. The crystal structure of Na₃PO₂S₂ was determined from X-ray powder diffraction data, and refined using the Rietveld technique (Pbca, a=17.5359(2) Å, b=11.3044(1) Å, c=5.8656(1) Å, R_F²=8.45%, R_p=4.80%, R_wp=6.79%). The baricenters of the PO₂S₂-tetrahedra are arranged in the sense of a hexagonal close packing. One of the P---O bonds of these tetrahedra is oriented parallel to the crystallographic c-axis with the POS₂-groups in an eclipsed mutual orientation. The crystal structure of Na₃PO₂S₂ displays a close relationship to the ones of Ca₃CrN₃ and Na₃POS₃. Above 330 °C, Na₃PO₂S₂ can be regarded as a fast ionic conductor (with σ>10⁻⁵ S cm⁻¹).     

Finite element simulation for dynamic large elastoplastic deformation in metal powder forming

In this paper, a transient dynamic analysis of the powder compaction process is simulated by a large displacement finite element method based on a total and updated Lagrangian formulation. A combination of the Mohr–Coulomb and elliptical yield cap model, which reflects the stress state and degree of densification, is applied to describe the constitutive model of powder materials. A Coulomb friction law and a plasticity theory of friction in the context of an interface element formulation are employed in the constitutive modelling of the frictional behaviour between the die and powder. Finally, the powder behaviour during the compaction of a plain bush, a rotational flanged and a shaped tip component are analysed numerically. It is shown that the updated Lagrangian formulation, using a combination of the Mohr–Coulomb and elliptical cap model, can be effective in simulating metal powder compaction.     

Syntheses and characterization of Sr(OH)2 and SrCO3 nanostructures by ultrasonic method

The Sr(OH)₂ and SrCO₃ nanostructures were synthesized by reaction of strontium(II) acetate and sodium hydroxide or tetramethylammonium hydroxide (TMAH) via ultrasonic method. Reaction conditions, such as the concentration of the Sr²⁺ ion, aging time, power of the ultrasonic device and alkali salts show important roles in the size, morphology and growth process of the final products. The pure crystalline SrCO₃ were obtained by heating of product at 400 °C. The Sr(OH)₂ and SrCO₃ nanostructures were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermal gravimetric (TG), differential thermal analyses (DTA) and the infrared spectroscopy (IR).     

Temperature Evolution of the Crystal Structure of AgNbO3

X-ray powder diffraction patterns of the AgNbO₃ have been obtained in a wide temperature range: from room temperature up to 850 K. The type of distortion and the multiplicity of the pseudo-cubic perovskite cell has been determined from the splitting of the main diffraction lines and from analysis of the superlattice peaks. The scheme of oxygen octahedra tilting and the sequence of the distorted pseudocubic cell is: <artwork name="GPHT21121eu1">