Preparation of Mg-Li-La alloys by electrolysis in molten salt

An electrochemical method was used to prepare Mg-Li-La alloys in a molten LiCl-KCl-KF-MgCl2 containing La2O3 at 943 K. The results showed preparation of Mg-Li-La alloys by electrolysis is feasible. The Mg-Li-La alloys were analyzed by means of X-ray diffraction （XRD）, optical micrograph （OM） and scanning electron microscopy （SEM）. XRD analysis indicates that α＋Mg17La2, α＋β＋Mg17La2 and β＋LaMg3 Mg-Li-La alloys with different lithium and lanthanum contents were obtained via galvanostatic electrolysis. The microstructures of typical α＋Mg17La2 and β＋LaMg3 phases of Mg-Li-La alloys were characterized by optical microscopy （OM） and scanning electron microscopy （SEM）. The analysis of energy dispersive spectrometry （EDS） shows that the element of Mg distributes homogeneously in the Mg-Li-La alloy and the element of La mostly exists at grain boundaries to restrain the grain growth rate due to the larger ionic radius and lower electronegativity compared with Mg.

LiCl-KCl体系中液态Zn阴极熔盐电解提取镨

利用液态金属作为阴极分离、提取稀土元素有很多优点。以液态金属Zn为阴极,研究Pr(Ⅲ)离子在液态Zn阴极上还原的电化学机理。在LiCl-KCl-PrCl_(3)熔盐中,分别采用循环伏安法、半积分法研究W电极和液态Zn电极上Pr(Ⅲ)的电化学还原过程。结果表明,在该实验温度下,只有一种富锌的Pr_(x)Zn_(y)金属间化合物生成。通过循环伏安法和半微分法计算了LiCl-KCl熔盐中Pr(Ⅲ)的扩散系数。根据电化学机理研究,采用液态金属Zn为阴极恒电位电解提取稀土Pr。电感耦合等离子体发射光谱仪(ICP)结果表明,随着电解时间的增长,熔盐中Pr(Ⅲ)离子的浓度逐渐降低。电解2 h后,提取效率为45.38%,当电解时间达到40 h时,提取效率为99.48%。X射线衍射(XRD)和扫描电镜-能谱(SEM-EDS)点分析结果表明,恒电位电解2 h得到的沉积物为Zn_(11)Pr_(3)。

Performance Improved by Incorporating of Ru Atoms into Zr-Si Diffusion Barrier for Cu Metallization

Thin Ru_(21)Zr_(64)Si_(15) films deposited on Si substrates by radio frequency reactive magnetron sputtering are studied and evaluated as diffusion barriers for Cu metallization.Cu/Ru_(21)Zr_(64)Si_(15)/Si and Cu/Zr_(67)Si_(33)/Si structure samples are prepared under the same procedures for comparison.The thermal stability,phase formation,surface morphology and atomic depth profile of the Cu/Ru_(21)Zr_(64)Si_(15)/Si and Cu/Zr_(67)Si_(33)/Si structures before and after annealing at different temperatures are investigated.In conjunction with these analyses,the Cu/Ru_(21)Zr_(64)Si_(15)/Si contact system shows high thermal stability at least up to 650℃.The results obtained reveal that the incorporation of Ru atoms into the Zr_(67)Si_(33) barrier layer is shown to be beneficial for improving the thermal stability of the Cu/barrier/Si contact system.

Comparison of the Sol-gel Method with the Coprecipitation Technique for Preparation of Hexagonal Barium Ferrite

Hexagonal barium ferrite BaFe12O19 particles were prepared by sol-gel and coprecipitation methods, respectively. The composition of the so-obtained materials was investigated by means of XRD. By the sol-gel method, non-anticipated intermediate crystalline phases, such as γ-Fe2O3, α-Fe2O3, BaCO3, and BaFe2O4 etc., were formed with the delay of the formation of BaFe12O19. The formation of single phase BaFe12O19 required calcination at 850 oC for 4 h. On the other hand, using coprecipitation technique, amorphous hydroxide precursor was directly transferred into BaFe12O19 almost without the formation of intermediate crystalline phases. BaFe12O19 was prepared by calcining at 700 oC for 3 h. The results were confirmed by ESEM and VSM analyses. Based on the already reported results and the observed results in this study, it can be concluded that the coprecipitaion technique is easier to control than the sol-gel method for preparation of BaFe12O19 at a low temperature.

Comparable Studies of Adsorption and Magnetic Properties of Ferrite MnFe_2O_4 Nanoparticles,Porous Bulks and Nanowires

The spinel ferrites MnFe2O4 nanowires were synthesized by hydrothermal route,porous MnFe2O4 and nanoparticles morphologies were synthesized by sol-gel method with egg white.The structures,morphologies,magnetic properties and adsorption properties of these obtained ferrites with different morphologies were studied contrastively.Results show that the obtained samples exhibit ferromagnetic properties.This realizes convenient magnetic separation from solution when they are used in the treatment of organic dyes wastewater.However,the contrastive studies show that the saturation magnetizations（Ms） of MnFe2O4 with different morphologies are different and the Ms follows the order：Ms（porous）〈Ms（nanoparticles）〈Ms（nanowires）.In addition,the adsorptions of methylene blue（MB） onto these ferrites depend on ferrites＇ morphologies seriously.The adsorption rate of MB on the porous MnFe2O4 is much higher than those onto the other two samples because the porous structure can provide high efficient mass transport through the pores.

英国的南极立法实践及其对中国的启示

通过梳理英国的南极立法的实践可以发现,出于地缘政治、经济利益、科研考察等方面的因素,英国在立法方面逐步加强了对南极事务的关注程度,其南极法律制度已逐步完善。中国可以从加强涉南极事务法律法规建设、加强南极科考力度、维护国家尊严、在南极事务国际合作中推动践行人类命运共同体理念等四个层面开展工作,从而更好地服务中国的南极事业。