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991.
A new complex of lanthanum orotate [La(C5H3N2O4)2(OH)(H2O)6 ]·2(C5H4N2O4)·9H2O was synthesized using a hydrothermal method. The crystal structure was determined with help of single crystal X-ray diffraction analysis. The complex crystallized in orthorhombic system, Cmc2(1) space group. In the complex, the center lanthanum (Ⅲ) ion was nine-coordinated with coordination geometry of a distorted monocapped square antiprism, in which two of the nine coordinated oxygen atoms were from two orotate ligands in a monodentate mode, one oxygen atom from a hydroxyl, and the others from six coordinated water molecules. The mononuclear complex [La(C5H3N2O4)2(OH)(H2O)6 ]·2(C5H4N2O4)·9H2O was linked through the hydrogen bonds into an infinite supermolecular honeycomb structure. 相似文献
992.
Guo Shiyi Yuan Duorong Shi Xuzhong Cheng Xiufeng Zhang Xiqing Yu Fapeng 《中国稀土学报(英文版)》2007,25(Z1):66-68
Single crystal of cobalt (Co)-doped Y3Sc2Ga3O12 (YSGG) with the dimensions up to φ20×40mm3 and undoped YSGG crystal with the dimensions up to φ28×60mm3 have been grown using the Czochralski technique. The structure of the crystal was characterized by the X-ray powder diffraction (XRPD) method. The absorbance spectra of the crystal shows that it has strong absorption bands at 606 and 1540nm. The results indicate that the crystal Y3Sc2Ga3O12 may be a kind of good Q-switch material. 相似文献
993.
994.
Yang Tan Feng Chen Lei Wang Yang Jiao 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2007,260(2):567-570
We report on the optical planar waveguides in Nd:YLiF4 laser crystals fabricated by 6.0 MeV C3+ ion implantation at doses of 1 × 1015 or 2.5 × 1015 ions/cm2, respectively. The refractive index profiles, which are reconstructed according to the measured dark mode spectroscopy, show that the ordinary index had a positive change in the surface region, forming non-leaky waveguide structures. The extraordinary index is with a typical barrier-shaped distribution, which may be mainly due to the nuclear energy deposition of the incident ions into the substrate. In order to investigate the thermal stability of the waveguides, the samples are annealed at temperature of 200–300 °C in air. The results show that waveguide produced by higher-dose carbon implantation remains relatively stable with post-irradiation annealing treatment at 200 °C in air. 相似文献
995.
996.
997.
998.
The paper discusses how physically based material models can contribute to the development and optimization of new materials. In combination with using enhanced simulation techniques such as density functional theory a true multi scale material development can be established. 相似文献
999.
A new technique has been developed to generate dendritic‐equiaxed structures in aluminium alloy casting processes, not only to improve the mechanical properties but also to study the effect of crystal structure on the chemical and physical properties of alloys to be cast. The investigation combined laboratory experimental work, metallographic examination and mathematic modelling. The laboratory experimental work involved different superheats for Al‐4.5%Cu alloy in cast ingots. Measurements of temperature distributions were conducted to verify the solidification model. A metallographic study combined macro and micro structural evolution of cast ingot samples. Two‐dimensional mathematical models of fluid flow and heat transfer were developed to characterise the natural convection streams and thermal fields. The model predictions were compared to temperature and isotherms measurements where a good agreement was found. The formation of cast structure and columnar, equiaxed transition (CET) and macro segregation phenomena were studied and discussed, based not only on the theories of nucleation but also on the thermal effects in the mushy and liquid zones. 相似文献
1000.
利用遗传算法和传输矩阵法计算一维光子晶体能带结构,将一维光子晶体用像素填充法进行二进制编码模拟,结果找到全方位相对禁带宽度达42.54%的4层结构和43.75%的2层结构;给出了一维光子晶体4层最佳结构的能带图、20个原胞的反射率透射率频谱图.发现一维2层光子晶体的全方位禁带宽度对每层厚度的变化是不敏感的,但是随着两种介质折射率差的增大而增大. 相似文献