金属铁相的分析进展

本文评述了金属铁相的分析进展,分置换反应分离法、氧化还原分离法和综合解方程法三个题目进行评述,参考文献58篇。

Oxidation behaviour and phase characterization of titaniferous magnetite ore of eastern India

Titaniferous magnetite ore is a kind of symbiotic complex ore which comprises ilmenite, magnetite, hercynite and magnesio-hercynite spinel minerals. The ore collected from eastern India was characterized by XRD, WDXRF, SEM and M？ssbauer spectroscopy. The oxidation behaviour of fine ore was investigated by TG-DTA analysis under oxygen atmosphere. Subsequent isothermal oxidation experiments were carried out under oxygen and air atmospheres, holding the samples for different periods of time at different temperatures from 873 K to 1473 K. It was observed that ilmenite phase transformed to hematite and titanium dioxide at lower temperature, whereas ferric-pseudobrookite phase was found at higher temperature. Direct reduction of oxidized sample-coke cylindrical briquettes was successfully achieved for phase transition from titaniferous magnetite to iron and titanium dioxide at 1473 K.

Numerical Analysis of Neodymium Magnet Influence in Relation Induction/Weight Structures of Sumo Robots

Since neodymium magnet possesses an extremely strong magnetic field, resulting from the combination of neodymium, iron and boron, it has become the most used in designing autonomous sumo robots. When it is mounted under the structure of this robot, the magnet produces a large amount of normal force resulting from the interaction between its field lines and the steel frame of the arena, reducing the risk of slipping its wheels. Thus, the heavier a robot, the greater the difficulty for the opponent to remove it from the arena. This article explains the properties of Nd-Fe-Br magnets and analyzes the influence of these characteristics in the relation induction/weight. Additionally, to a comparative analysis, this research analyzes the positioning, geometry and polarization of the magnets under study, based on numerical results obtained using Inventor and K ＆ J Magnets Calculator software, given that these factors influence in their energetic product generation. Furthermore, more than just working with what we believe is a subject of great interest for sumo robot＇s teams, this study encourages their competitiveness, an essential factor for the competition.

Synthesis of Large-Area, Few-Layer Graphene on Iron Foil by Chemical Vapor Deposition

We demonstrate a simple and controllable way to synthesize large-area, few-layer graphene on iron substrates by an optimized chemical vapor deposition （CVD） method using a mixture of methane and hydrogen. Based on an analysis of the Fe-C phase diagram, a suitable procedure for the successful synthesis of graphene on Fe surfaces was designed. An appropriate temperature and cooling process were found to be very important in the synthesis of highly crystalline few-layer graphene. Graphene-based field-effect transistor （FET） devices were fabricated using the resulting few-layer graphene, and showed good quality with extracted mobilities of 300-1150 cm2/（V.s）.

Discovery of a novel 112-type iron-pnictide and La-doping induced superconductivity in Eu_(1-x)La_xFeAs_2(x=0–0.15)

We report the discovery and characterization of a novel 112-type iron pnictide EuFeAs2, with La-doping induced superconductivity in a series of Eu1- xLaxFeAs2. The polycrystalline samples were synthesized through solid state reaction method only within a very narrow temperature window around 1073 K. Small single crystals were also grown from a flux method with the size about 100μm. The crystal structure was identified by single crystal X-ray diffraction analysis as a monoclinic structure with space group of P2 1/m. From resistivity and magnetic susceptibility measurements, we found that the parent compound EuFeAs2 shows distinct anomalies probably due to the Fe2＋ related antiferromagnetic/structural phase transition near 110K and the Eu2＋ related antiferromagnetic phase transition near 40K. La-doping suppressed both phase transitions to lower temperatures and induced superconducting transitions with a Tc - 11 K for Eu0.85La0.15FeAs2.

Di- and tetranuclear heterometallic CuⅡ-LnⅢ complexes (Ln = Gd and Dy): Synthesis, structure and magnetic properties

Four 3d-4f heterometallic complexes, [CuⅡ-LnⅢ(bpt)2(NO3)3(MeOH)] (Ln = Gd, 1; Dy, 2; bptH = 3,5-bis(pyrid-2-yl)-l,2,4- triazole), [CuⅡ-LnⅢ(μ-OH)2(bpt)4C14 (H2O)2]·6H2O (Ln = Gd, 3; Dy, 4), have been synthesized under solvothermal condi- tions. X-ray structural analyses reveal that 1 and 2 are isostructural while 3 and 4 are isostructural. In each complex, the copper and gadolinium or dysprosium ions are linked by two triazolate bridges and form a CuⅡ-LnⅢ dinuclear unit. The intramolecu- lar Cu-Ln distances are 4.542, 4.525, 4.545 and 4.538 ] for 1, 2, 3 and 4, respectively. Two dinuclear CuLn units are bridged by two OH- groups into the zig-zag tetranuclear {cunzLnm2} structures with the Ln(Ⅲ)...Ln(Ⅲ) distances of 3.742 and 3.684 for 3 and 4, respectively. Magnetic studies show that the antiferromagnetic CulI-Lnm interactions occur in 1 (Jcu = -0,21 cm-1) and 2. The antiferromagnetic interaction occurs in complex 3 with JcuGa = -0.82 cm-1 and JcdGd = --0.065 cm-1, while domi- nant ferromagnetic interaction occurs in complex 4.

An unexpected tetranuclear Li_2Cr_2 trimethylsilylacetylide complex bridged by two μ_3-pyrazolates

A tetranuclear Li2Cr2 acetylide precursor complex, [Li(Tp)crm(c=CSiMe3)2(/,t3-pz)]2· (n-pentane)2 (Tp = hydridotris(pyra- zolyl)borate, pz = pyrazolate) (1) has been synthesized and characterized. The X-ray structure analysis shows that the complex contains a Li2Cr2 core bridged by two ,u3-pyrazolates. The magnetic data exhibit the existence of weak antiferromagnetic in- teraction in the cluster.

Cyanido-bridged one-dimensional systems assembled from [Re~ⅣCl_4(CN)_2]_(2-) and [M~Ⅱ(cyclam)]^(2+) (M=Ni,Cu) precursors

Three new cyanido-bridged heterometallic ReIVNin and ReIVCu one-dimensional systems were synthesized and extensively characterized both structurally and magnetically. Single-crystal X-ray diffraction analysis revealed that these compounds display a common topology, with chains composed of alternating [RetVc14（CN）2]2- and [Mn（cyclam）]2＋ （M = Ni in 1, Cu in 2） or [Cull（N,N＇-dimethylcyclam）]2＋ （in 3） building units. Two different chain orientations with a tilt angle of ca. 51° to 55° are present in the crystal packing of these compounds. The magnetic susceptibility measurements suggest the presence of intrachain ferromagnetic interactions between the S = 3/2 ReTM centers and the 3d metal ions： S = 1 Ni1I or S = 1/2 CuII. At low temperature, a three-dimensional ordered magnetic phase induced by interchain antiferromagnetic interactions （antiferromagnetic for 1 and 2; canted antiferromagnetic for 3） is detected for the three compounds.