三桥连双铁(III)配合物[Fe_2(IDB)_2(O)(CH_3CO_2)_2]Cl_2·CH_3OH的晶体结构及其傅立叶变换拉曼光谱(英文)

合成了一种新的三桥连双铁 (III)配合物 [Fe2 (IDB) 2 (O) (CH3CO2 ) 2 ]Cl2 ·CH3OH ,IDB为N ,N’ -di(2’ -benzimidazolylmethyl)imine,利用单晶X射线衍射及其它谱学方法对所合成配合物进行了表征。每个双核单元的两个铁原子均通过一个氧原子和两个醋酸根连接 ,每个铁原子同时还与位于桥氧原子对位的三齿配体IDB重脂肪链上氮原子相结合 ,每个铁 (III)中心为一变形八面体结构。对该新化合物的拉曼光谱进行了研究并对一些谱峰进行了归属     

三桥连双铁(Ⅲ)配合物[Fe2(IDB)2(O)(CH3CO2)2]Cl2·CH3OH的晶体结构及其傅立叶变换拉曼光谱

合成了一种新的三桥连双铁(Ⅲ)配合物[Fe2(IDB)2(O)(CH3CO2)2]Cl2·CH3OH,IDB为N,N'-di(2'-benzimidazolyl methyl) imine,利用单晶x射线衍射及其它谱学方法对所合成配合物进行了表征.每个双核单元的两个铁原子均通过一个氧原子和两个醋酸根连接,每个铁原子同时还与位于桥氧原子对位的三齿配体IDB重脂肪链上氮原子相结合,每个铁(Ⅲ)中心为一变形八面体结构.对该新化合物的拉曼光谱进行了研究并对一些谱峰进行了归属.     

氧化锌纳米带中的面缺陷

面缺陷是纳米带中非常普遍和非常重要的一类缺陷。在有些情况下，面缺陷对于高表面能指数面的出现起着决定性的作用。同时。它们可以诱导纳米带沿着特殊的方向生长。面缺陷可以是孪晶或双晶，层错和由杂质原子聚集在特定原子面所形成的间隙原子层。在本文中。利用透射电子显微术，我们将介绍氧化锌纳米带中被发现的几种面缺陷。我们确认了两种孪晶／双晶结构，它们的孪晶面分别是（01^-13）和（^-2112）面。基面层错有I1和I2两种。在大尺寸的纳米带中，I1基面层错可以折叠到（2^110）面形成棱面层错。当少量的In离子掺入氧化锌纳米带后，我们发现伴随着杂质In在基面的聚集，形成了两种倒反畴界。     

Twin Boundaries in Zinc Oxide with Additions of Gallium Oxide

Twin boundaries (TBs) in ZnO sintered with small additions of Ga₂O₃ have been characterized with advanced methods of transmission electron microscopy (TEM). The TBs and accompanying inversion domain boundaries are on {011¯3} planes of ZnO. The Ga content of the TB corresponds to an effectively half occupied {011¯3} plane determined from compositional maps calculated from electron spectroscopic images using electron filtering TEM. The structure of the TBs were investigated by high-resolution TEM, and images of focus series were used to reconstruct the complex electron wave. Simulated electron waves based on structure models of the TB were quantitatively compared with the reconstructed wave to identify and to refine atom positions. The twins can be considered to be created by a mirror operation on a {011¯3} plane of ZnO, and two alternating closed-packed polyhedral clusters of oxygen ions can be identified as building units of the TB structure. Unit 1 is occupied with Zn²⁺ by simply continuing ZnO₄ tetrahedra of the same type from both crystals to the TB. Using arguments of local charge balance unit 2 can only be occupied with the trivalent Ga³⁺ ion. The Ga³⁺ position was refined with high precision (±5 pm), and the resulting polyhedron is a GaO₅ square pyramid. The pyramids form densely occupied columns parallel to the twin axis [21¯1¯0]. The analysis of the TB structure yields a fractional occupancy of the boundary plane by Ga of 0.5, which is in good agreement with the result of the chemical composition measurement with energy filtered TEM.     

Influence of domain boundaries on polarity of GaN grown on sapphire

GaN films were grown on sapphire substrates by laser-induced reactive epitaxy. The domains in the films were determined to be the Ga-polarity by the convergent beam electron diffraction (CBED) technique, while the adjacent matrices had the N-polarity. The domain boundaries were characterized as inversion domain boundaries (IDBs). An atomic structure of the IDB is proposed based on high-resolution transmission electron microscopy (HRTEM) investigations. Control of the polarity of GaN/sapphire films was achieved by suppressing the formation of IDBs with an interlayer of AlGaN and a low-temperature GaN buffer layer.     

Observation of inversion domain boundaries in Mg-doped AlGaN layers grown by metalorganic chemical vapor deposition

We have investigated the formation of inversion domain boundaries in Al_0.13Ga_0.87N layers grown on sapphire substrates by metalorganic chemical vapor deposition using transmission electron microscopy (TEM). We found that the shape of inversion domain boundaries strongly depends on Mg source flow rate in the Mg-doped Al_0.13Ga_0.87N layers. By increasing the Mg source flow rate, the shape of inversion domain boundaries is changed from the vertical shape to the horizontal shape. In addition, the change of polarity by the horizontal shape inversion domain boundary (IDB) resulted in the inverted rotation of pyramidal shape IDB within the Mg-doped Al_0.13Ga_0.87N layers.     

四方铁电体PbFe0.5Nb0.5O3精细结构的第一性原理研究

采用全电势线性缀加平面波法(FPLAPW),计算了PbFe0.5Nb0.5O3的总能量,从而确定了它的四方铁电稳态结构,即B位离子(Fe和Nb)在四方铁电相的平衡构型.计算结果表明,Fe相对于氧八面体沿[001]方向的位移为0.022nm,而Nb的偏心位移为0.0020nm,其中铁电非稳性主要归因于前者 关键词： 铁电体 密度泛函理论 平面波法     

利用原位红外光谱研究若干过渡金属氧化物-丙酸体系，Fe2Cr（μ3-O）（μ-O2CC2H5）6（H2O）3Cl*xH2O及Cr3（μ3-O）（μ-O2CC2H5）6（H2O）3NO3*xH2O的反应行为

利用原位红外光谱法研究标题化合作在N2 中的反应行为。发现它们在不同温度下能使丙酸分别转化为乙醛和戊酮。金属氧化物对丙酸的戊酮化反应活性顺序是 :Fe3O4 >MnO2 >Cr2 O3>Co2 O3>Ni2 O3,这顺序与下列簇合物对该反应的活性顺序类似 :[Fe2 MnOPH]>[Fe3OPH]>[Fe2 CrOPH]>[Fe2 CoOPH]>[Fe2 NiOPH]>[Cr3OPH][OPH =(μ3 O) (μ O2 CC2 H5) 6(H2 O) 3]。对于戊酮化反应 ,过渡金属氧化物的反应温度明显高于相应的 [Fe2 MOPH]的反应温度 ,这旁证了 [Fe2 MOPH]的活性组分不是其金属氧化物。还讨论了Fe3O4 ,Fe2 O3 对丙酸分别转化为乙醛和戊酮反应活性的明显差异。     

First-Principles Study on Magnetic Properties of V-Doped ZnO Nanotubes

Electronic and magnetic properties of V-doped ZnO nanotubes in which one of Zn^2＋ ions is substituted by V^2＋ ions are studied by the first-principles calculations of plane wave ultra-soft pseudo-potential technology based on the spin-density function theory. The computational results reveal that spontaneous magnetization in Vdoped （9,0） ZnO nanotubes can be induced without p-type or n-type doping treatment, and the ferromagnetism is isotropic and independent of the chirality and diameter of the nanotubes. It is found that V-doped ZnO nanotubes have large magnetic moments and are ferromagnetic half-metal materials. Moreover, the ferromagnetic coupling among V atoms is generated by O 2p electron spins and V 3d electron spins localized at the exchanging interactions between magnetic transitional metal （TM） impurities. The appearance of ferromagnetism in V-doped ZnO nanotubes gives some reference to fabrication of a transparent ferromagnet which may have a great impact on industrial applications in magneto-optical devices.     

Effect of iron doping concentration on magnetic properties of ZnO nanoparticles

The ZnO:Fe nanoparticles of mean size 3-10 nm were synthesized at room temperature by simple co-precipitation method. The crystallite structure, morphology and size estimation were performed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM). The wurtzite structure of ZnO gradually degrades with the increasing Fe doping concentration. The magnetic behavior of the nanoparticles of ZnO with varying Fe doping concentration was investigated using a vibrating sample magnetometer (VSM). Initially these nanoparticles showed strong ferromagnetic behavior, however at higher doping percentage of Fe, the ferromagnetic behavior was suppressed and paramagnetic nature was observed. The enhanced antiferromagnetic interaction between neighboring Fe-Fe ions suppressed the ferromagnetism at higher doping concentrations of Fe. Room-temperature Mössbauer spectroscopy investigation showed Fe³⁺ nature of the iron atom in ZnO matrix.     

Jahn-Teller stabilization of a "polar" metal oxide surface: Fe3O4(001)

Using ab initio thermodynamics we compile a phase diagram for the surface of Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto ignored polar termination with octahedral iron and oxygen forming a wavelike structure along the [110] direction is identified as the lowest energy configuration over a broad range of oxygen gas-phase conditions. This novel geometry is confirmed via x-ray diffraction analysis. The stabilization of the Fe3O4(001) surface goes together with dramatic changes in the electronic and magnetic properties, e.g., a half metal to metal transition.     

High-frequency excitations of stripe-domain lattices in magnetic garnet films

Magnetic garnet films of composition (Y,Bi)₃(Fe,Al)₅O₁₂ have been grown by liquid phase epitaxy on [111] and [110] oriented substrates of gadolinium gallium garnet. The domain wall resonance and the two branches of the domain resonance of periodic stripe domains are measured as function of the bias induction applied in the film plane parallel to the stripes. Resonance frequencies up to 7.5 GHz are observed. An improved version of the hybridization model is developed to describe these resonances. It turns out that hybridization of the domain resonance branches is determined by the cubic anisotropy for [111] oriented films, while for [110] oriented films coupling of the domain resonances is mainly caused by the orthorhombic anisotropy. The theoretical model is in excellent agreement with experiments, no fitting parameters are used. It is also used to derive the phase relation between the precessing magnetizations of neighbouring domains.     

Spin coupling in iron proteins and model complexes

Transition metal ions are essential for the specific function of many biomolecules, like transport and activation of small molecules, electron transfer, etc. Their active sites contain (i) single paramagnetic or diamagnctic metal ions, or (ii) clusters of spin-coupled paramagnetic centers. Examples are for (i) hemoglobin or rubredoxin with one Fe, and for (ii) ferredoxins with [2Fe-2S] and [4Fe-4S] clusters, cytochrome c oxidasc containing Fe and Cu, or peroxidases with metal-radical pairs. Here, we present the results of our Mössbauer and EPR investigation of irondioxygen interaction in horse liver alcohol dehydrogenase (HLADH), of ironradical interaction in synthetic analogues of heme peroxidases and of iron-iron double exchange interaction in a synthetic ferric/ferrous mixed valence complex. We hope to demonstrate that the understanding of spin coupling can yield valuable insight in the relation between electronic structure and function of biological iron complexes.

     

高质量ZnO微米棒的制备及其光学性质

利用水热法制备ZnO微米棒。醋酸镁[Mg(CH3COO)2.4H2O]、醋酸锌[Zn(CH3COO)2.2H2O]和六次甲基四胺(C6H12N4)以一定比例配置成反应溶液,把反应溶液加热到90℃,反应时间为24h,能够在硅衬底上生长高质量的ZnO微米棒。用扫描电镜(SEM)和X射线衍射仪对ZnO微米棒的晶体结构和表面形貌进行了分析,结果表明,样品为细长条棒状结构,呈现六方纤锌矿结构,长径比可达10∶1,并且在[002]方向择优生长。在样品中并未发现镁离子,它有可能扮演着催化剂的角色。对ZnO微米棒的光致发光性能进行测量,由PL光谱分析可知,样品在384nm处有一个紫外发光峰,半峰全宽为13nm,紫外发光峰强度比可见发光峰强度大的多,样品的质量较好。     

The Fe/ZnO(0 0 0 1) interface: Formation and thermal stability

The room temperature growth mode and the interface reaction of Fe films on single crystalline ZnO(0 0 0 1) substrates prepared in ultra high vacuum (UHV) has been investigated by means of X-ray photoelectron and Auger electron spectroscopy (XPS, AES), low energy electron diffraction (LEED) and low energy ion scattering spectroscopy (LEIS). The results show that Fe grows in the pseudo layer-by-layer mode. At ambient temperature the deposited Fe film reduces the underlying ZnO single crystal resulting in FeO at the interface and metallic Zn, which partially diffuses into the remaining Fe overlayer. Annealing leads to a stepwise oxidation of the Fe to FeO (670 K) and Fe₂O₃ (820 K). The Fe₂O₃ mixes with the substrate resulting in two (1 1 1) oriented textures of a spinel phase found by electron backscatter diffraction analysis (EBSD). Fe-based spin-injection may play a vital role for ZnO-based spintronic devices.     

High-frequency and -field EPR and FDMRS study of the [Fe(H2O)6]2+ ion in ferrous fluorosilicate

The complex [Fe(H2O)6]SiF6 is one of the most stable and best characterized high-spin Fe(II) salts and as such, is a paradigm for the study of this important transition metal ion. We describe high-frequency and -field electron paramagnetic resonance studies of both pure [Fe(H2O)6]SiF6 and [Zn(H2O)6]SiF6 doped with 8% of Fe(II). In addition, frequency domain magnetic resonance spectroscopy was applied to these samples. High signal-to-noise, high resolution spectra were recorded which allowed an accurate determination of spin Hamiltonian parameters for Fe(II) in each of these two, related, environments. For pure [Fe(H2O)6]SiF6, the following parameters were obtained: D=+11.95(1) cm(-1), E=0.658(4) cm(-1), g=[2.099(4),2.151(5),1.997(3)], along with fourth-order zero-field splitting parameters: B4(0)=17(1)×10(-4) cm(-1) and B4(4)=18(4)×10(-4) cm(-1), which are rarely obtainable by any technique. For the doped complex, D=+13.42(1) cm(-1), E=0.05(1) cm(-1), g=[2.25(1),2.22(1),2.23(1)]. These parameters are in good agreement with those obtained using other techniques. Ligand-field theory was used to analyze the electronic absorption data for [Fe(H2O)6]SiF6 and suggests that the ground state is 5A1, which allows successful use of a spin Hamiltonian model. Density functional theory and unrestricted Hartree-Fock calculations were performed which, in the case of latter, reproduced the spin Hamiltonian parameters very well for the doped complex.     

Polarity control and residual strain in ZnO epilayers grown by molecular beam epitaxy on (0001) GaN/sapphire

We report on the polarity control of ZnO grown by plasma assisted molecular beam epitaxy on Ga polar (0001) GaN/sapphire templates simply via the oxygen‐to‐Zn (VI/II) ratio during the growth of a thin nucleation layer at 300 °C. Following Zn pre‐exposure, the ZnO layers nucleated with low VI/II ratios (<1.5) exhibited Zn‐polarity. Those nucleated with VI/II ratios above 1.5, exhibited O‐polarity. Supported by scanning transmission electron microscopic imaging, we have unequivocally demonstrated that polarity inversion takes place without formation of any vertical inversion domains and within one monolayer of presumably non‐stoichiometric GaO_x formed at the ZnO/GaN interface. A direct correlation between polarity and strain sign of ZnO layers has been found. The Zn‐polar ZnO layers were under tensile biaxial strain, whereas the O‐polar material exhibited compressive strain. Moreover, the amount of residual strain varied linearly with VI/II ratio used during the low‐temperature nucleation layer growth. Strain control with VI/II ratio has been explained by the potential formation of Zn interstitials.     

基于可见光-近红外光谱的BIF磁性率确定方法研究

铁矿中磁性率是评价铁矿床工业价值和划分矿石工业类型的重要指标。传统的磁性率测定法存在工作量大、效率低、周期长的缺陷,成为经济、合理、高效开采铁矿资源的瓶颈问题。采用便携式地物光谱测试仪对辽宁省鞍钢集团鞍千矿业有限责任公司的BIF实验样品进行可见光-近红外光谱测试,分析了光谱特征,构建了比值指数(RI)、差值指数(DI)和归一化指数(NDI),并确定光谱指数与样品磁性率相关性最显著的敏感波段及对应的相关系数值;优选出与样品磁性率相关性最显著的比值指数(RI),构建实验样品磁性率的定量反演模型,并进行了验证。结果表明,三种光谱指数与样品磁性率敏感波段均位于935与1 050 nm,且该波段处的相关系数均达到0.9以上,其中比值指数与样品磁性率的相关性最高;基于比值指数构建的实验样品磁性率定量反演模型的预测误差为0.038,反演磁性率与实测磁性率的判定系数(R2)为0.964 5,预测结果比较理想。为确定BIF的磁性率提供了一种新方法,该方法具有工作强度小、经济、高效、便捷的优点,且对遥感找矿具有一定指导意义。