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981.
982.
The molecular geometry and vibrational frequencies of the [2-Oxo-2-(4-acetyl) phenyl amino] ethylene methacrylate (APEMA) were examined theoretically using the Hartree–Fock and Density function method (B3LYP) with 6-31G(d) basis set. The calculated geometrical parameters of the investigated molecule were compared with experimental data. Both the calculated structural parameters and vibrational frequencies are in good agreement with the available experimental data. 相似文献
983.
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. 相似文献
984.
Abstract Single crystals of MoS x Se2?x (x=0, 1, 2) have been grown by direct vapour transport method. Pressure-dependent d.c. electrical resistivity measurements have been carried out on the grown crystals to check the possibility of phase transition up to 8 GPa. However, no such transition is observed in the present case but a decrease in resistivity is found with increase in pressure. The observed results have been analysed and discussed on the basis of band structure. 相似文献
985.
Advances in materials performance often require the development of composite system. In the present investigation, SiO2-reinforced nickel composite coatings were deposited on a mild steel substrate using direct current electrodeposition process employing a nickel acetate bath. Surface morphology, composition, microstructure and crystal orientation of the Ni and Ni-SiO2 nanocomposite coatings were investigated by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction analysis, respectively. The effect of incorporation of SiO2 particles in the Ni nanocomposite coating on the microhardness and corrosion behaviour has been evaluated. Smooth composite deposits containing well-distributed silicon oxide particles were obtained. The preferred growth process of the nickel matrix in crystallographic directions <111>, <200> and <220> is strongly influenced by SiO2 nanoparticles. The average crystallite size was calculated by using X-ray diffraction analysis and it was ~23 nm for electrodeposited nickel and ~21 nm for Ni-SiO2 nanocomposite coatings. The crystallite structure was fcc for electrodeposited nickel and Ni-SiO2 nanocomposite coatings. The incorporation of SiO2 particles into the Ni matrices was found to improve corrosion resistance of pure Ni coatings. The corrosion potential (E corr) in the case of Ni-SiO2 nanocomposite coatings had shown a negative shift, confirming the cathodic protective nature of the coating. The Ni-SiO2 composite coatings have exhibited significantly improved microhardness (615 HV) compared to pure nickel coatings (265 HV) 相似文献
986.
Ionic liquid glow discharge electrolysis for nanoparticle synthesis is an emerging nanomaterials processing technology and the stability of ionic liquid when they are in contact with plasma is an important issue. This paper discusses the stability of [BMIM][BF4] after exposing this ionic liquid to glow discharge plasma and the synthesis of cubic crystalline ZnS nanoparticles by plasma electrochemical method. Stability of the ionic liquid after plasma exposure to 20 min at 250 V is explained by their FTIR spectra and found that the ionic liquid is stable even after the plasma exposure. 相似文献
987.
夏继宏 《原子与分子物理学报》2013,30(6)
本文利用分子动力学模拟方法, 研究了液态Ti75Al25合金在不同冷却条件下形成晶体及非晶的过程(Q1:1.0×1013 Ks-1, Q2: 1.0×1011 Ks-1). 利用平均原子体积、双体分布函数、键角分布函数、键对分析和Voronoi多面体方法研究了微观局域结构随温度的变化关系. 研究发现:在Q1冷却过程中,液态Ti75Al25合金在1000 K发生玻璃化转变,形成非晶结构; 而在Q2冷却过程中,液态Ti75Al25合金发生结晶,并最终形成hcp晶体结构。 相似文献
988.
The electronic structures of Laves phase compounds AB2 (A = Y, Zr, Nb; B = Cr, Mn, Co, Ni) were investigated systematically by the LMTO method within the framework of the LSD approximation. Comparing the calculated total energy for hypothetical para-, ferro-, and antiferromagnetic state with the C14 and the C15 structure, the theoretical predictions are in good agreement with the experiments concerning the stability of the crystal structure and the magnetism. The magnetic stability critically depends upon the change of the lattice spacing, which leads to the colorful behaviors of the magnetism in Fe Laves phase compounds and the anomalous volume change in the antiferromagnetic state of YMn2. 相似文献
989.
T. Yamaguchi N. Yamamoto M. Inui S. Tsutsui 《Journal of Physics and Chemistry of Solids》2005,66(12):2246-2249
Inelastic X-ray scattering experiments on sub- and supercritical water were performed to investigate collective dynamics of this unique solvent. Analysis within a generalized Langevin formalism shows that the positive dispersion of the sound velocity, as compared to the hydrodynamic value, first decreases (1.0<ρ<0.8 g cm−3) at all measured momentum transfers (1.3-10.7 nm−1), and then increases (0.7<ρ<0.26 g cm−3) again only at higher momentum transfers. We suggest the initial decrease is due to approaching the percolation limit in the number of hydrogen bonds, and the subsequent increase is due to the formation of rigid dimers in sub- and supercritical water. 相似文献
990.
The objective of this Letter is to provide an efficient and reliable analytical procedure for the generalized Bloch–Gruneisen function with the Debye temperatures for the wide temperature range using the binomial expansion theorems. As will be seen, the present formulation yields compact closed-form expressions which enable the ready calculation of Bloch–Gruneisen function for integer and noninteger values of parameter m. The proposed procedure guarantees the reliable application of the contribution of electron–photon interaction to the electrical resistivity of metals. Finally, the algorithm is used to simulate the variation of the resistivity and thermal conductivity against temperature sintered polycrystalline MgB2. Furthermore, the comparison of the method with numerical calculations demonstrates the applicability and accuracy of the method. 相似文献