Electrical Conductivity of Liquid Sb and Bi Doped with 3d Transition Metals

The electrical conductivity of liquid Sb and Bi doped with 3d transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) was measured. The results demonstrate that small (3 at. %) additions of these metals reduce the conductivity of the melts by up to 4%, except for Ni and Cu, which slightly raise the conductivity of liquid Sb. This finding is interpreted in terms ofs–d hybridization. The scattering of electrons is considered using the Friedel–Anderson approach, based on the concept of virtual bound states.     

Magnetism of 3d Transition Metals Doped 2H, 4H and 6H-GaN Polytypes

We present spin-polarized density-functional theory study of substitutional 3d transition metal (TM) atoms (Sc → Ni) in various host polytypes of GaN. For the structural parameters, we found that a(c) decreases (increases) from Sc to Ni. Additionally, calculations reveal decreasing (increasing) of the lattice constants a (c/a ratio) with increasing hexagonality h. In spite of the small cell used, TM atoms doped GaN polytypes with Ti, Cr, Mn, Fe, Co, and Ni show ferromagnetic character; whereas Sc and V dopant systems show, respectively, semiconducting and metallic behavior. The origin behind magnetism in 3d transition metal atoms doped 2H, 4H, and 6H-GaN polytypes is clarified through the ordering of spin-up (t+, e+) and spin-down (t-, e-) states.     

3d过渡族金属杂质在硅中的行为

本文综述了３ｄ过渡族金属在直拉硅单晶中的扩散、溶解、沉淀及间隙位演变等性质，介绍了国际上在此领域的研究进展，为进一步开展这方面的工作提供了有益的借鉴。     

Synthesis and Characterization of Transition Metals Doped ZnO Nanorods

Different morphologies of undoped and transition metals(Mn,Co and Ni) doped one-dimensional(1D) ZnO nanocrystals were successfully synthesized by chemical method in an air atmosphere using polyvinylpyrrolidone(PVP) as a surfactant.The structure and optical properties were studied by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD),thermal gravimetric analysis(TGA),ultraviolet visible(UV-vis) absorption spectra and photoluminescence(PL) spectra.The doped ZnO nanorods exhibited a blue-shifted band gap and enhanced ultraviolet(UV) emission.In addition defect related emission was observed for the doped ZnO.     

Synthesis and Magnetic Properties of SrO–Fe2O3–B2O3 Glass-Ceramics

Glasses with nominal compositions of SrFe₁₂O₁₉ + 8SrB₂O₄ (I) and SrFe₁₂O₁₉ + 12Sr₂B₂O₅ (II) are prepared by rapid quenching from the liquid state and are converted to glass-ceramics containing fine magnetic particles of SrFe₁₂O₁₉ by heat treatment between 600 and 950°C. The materials are characterized by x-ray diffraction, differential thermal analysis, electron microscopy, and magnetic measurements. The phase transformations accompanying glass crystallization are identified. The glass composition and heat-treatment conditions are shown to influence the aspect ratio of the forming submicron-sized strontium hexaferrite particles. The strongest coercive fields reached in glass-ceramics I and II are 504 and 456 kA/m, respectively.     

掺杂LaMnO3体系的磁性和热性研究进展

对掺杂LaMnO3体系的异常磁性、磁电行为的物理模型、巨磁熵行为、以及这类物质在居里点附近的反常热性行为研究进行了综述,提出了可能的研究方向.     

过渡金属掺杂金红石相TiO2能带结构的第一性原理计算

本文采用第一性原理能带计算方法和超晶胞模型计算金红石相TiO2掺杂过渡金属元素的电子结构.计算结果表明,Zn掺杂对TiO2的带隙宽度影响不明显,V、Cr、Mn、Fe、Co、Ni、Cu的掺杂都有可能使TiO2吸收带出现红移现象或产生在可见光区的吸收,其中杂质原子的t2g态起了重要作用.     

Magnetic Behaviors of 3d Transition Metal-Doped Silicane: a First-Principle Study

We perform a first-principle computation on the magnetic properties of 3d transition metal (TM)-doped silicane. All the substituted systems are energetically stable. Robust half-metallic properties are found in Ti-, V- and Mn-substituted silicane. At the dopant concentration of 12.5%, we evaluate that the Curie temperature of Ti- and Mn-substituted silicane is at 340 and 666 K respectively in the mean-field approximation. Consequently, room-temperature ferromagnetism is easily achievable in Ti- and Mn-substituted silicane. Our work demonstrates potential application of Ti and Mn-substituted silicane for room-temperature spintronic devices.     

Magnetic Properties of Enriched 195Pt Metals

An enriched ¹⁹⁵Pt system was investigated by magnetic and NMR measurements. Anomalous large magnetic moments are distinctly observed in enriched ¹⁹⁵Pt wire samples produced by ORNL and in enriched thin-film samples. In the enriched powder and natural wire samples, weak anomalous large magnetic moments were also observed in magnetic measurements. These anomalous large magnetic moments were discussed by the induced giant magnetic moments of Fe impurity. The induced magnetic moments are different in wire samples and powder samples.     

Magnetic Properties of Several Transition Metal Silicomolybdates with a Magnetic Pyrochlore Lattice

We describe the low-temperature magnetic susceptibilities of M₂²⁺SiO₄[MoO₃]₁₂×30H₂O, with M = Mn, Co, Fe, and Ni. Magnetic order is visible in Mn₂SiO₄[MoO₃]₁₂×30H₂O, possibly due at least in part to the magnetic dipole–dipole interaction, and magnetic frustration is suggested by the behavior of Co₂SiO₄[MoO₃]₁₂×30H₂O and Ni₂SiO₄[MoO₃]₁₂×30H₂O. Fe₂SiO₄[MoO₃]₁₂×30H₂O exhibits a nonmagnetic ground state, with a very small splitting between the ground and first excited states of Fe²⁺.      

含锰锌铁氧体磁性生物活性玻璃陶瓷制备工艺及其性能研究

在磷灰石/硅灰石生物活性玻璃陶瓷(A-WGC)中掺杂锰锌铁氧体, 制备出一种新型的磁性生物活性玻璃陶瓷, 并研究了不同制备工艺对其磁性和生物活性的影响. 结果表明, 使用不同掺杂工艺制备的材料的主晶相均为硅灰石、磷灰石、氟磷灰石和分子式为Zn_0.75Mn_0.75Fe _1.5O₄的锰锌铁氧体. 在充磁至7.96×10⁵A·m^-1时, 各材料的饱和磁化强度相差不大, 在5.4~5.9A·m²·kg^-1之间. 材料的生物活性与烧结前和锰锌铁氧体前驱体复合的A-WGC原料的反应活性有关, A-WGC原料的反应活性越低, 材料的生物活性越好. 比较各材料, 采用将A-WGC前驱体高温煅烧后再与锰锌铁氧体前驱体固相混合的工艺制备的材料具有良好的磁性和较高的生物活性.     

Synthesis and Magnetic Properties of SrO–Fe2O3–B2O3–Bi2O3 Glass-Ceramics

Glass of nominal composition SrFe₁₂O₁₉ + 12SrB_1.5Bi_0.5O₄ is prepared by rapid quenching from the liquid state and is converted to glass-ceramics containing fine SrFe₁₂O₁₉ particles by heat treatment between 600 and 850°C. The materials are characterized by Mössbauer spectroscopy, x-ray diffraction, differential thermal analysis, electron microscopy, and magnetic measurements. All of the Fe in the glass is shown to be in the oxidation state 3+. The phase transformations accompanying glass crystallization are identified. The coercive field of the samples is shown to increase from 188 to 504 kA/m as the heat-treatment temperature is raised from 600 to 850°C. The composite prepared by heat treatment at 850°C contains submicron-sized SrFe₁₂O₁₉ particles with a thickness-to-diameter ratio of 0.33.     

参杂尖晶石型镍基铁氧体的磁性能与介电性能

采用溶胶-凝胶法制备了立方晶系尖晶石型镍基铁氧体微粉Ni0.5M0.5Fe2O4（M=Zn、Mn、Cu）,采用X射线衍射仪、扫描电子显微镜、振动样品磁强计和矢量网络分析仪对粉末的结构、形貌、磁性以及电磁性能进行了表征,结果表明,三种粉末在室温下具有超顺磁性,其饱和磁化强度MS分别为76．0、59．4和54．4emu·g-1。在2—11GHz范围内,Ni0.5M0.5Fe2O4的电磁损耗角正切值tgδ随频率的增大而逐渐减小;Ni0.5M0.5Fe2O4和 Ni0.5M0.5Fe2O4的tgδ随频率的增大先增大后减小。     

掺CaO-B2O3-SiO2玻璃烧结制备MnZn铁氧体及其磁性能

采用传统陶瓷工艺制备了CaO-B2O3-SiO2(CBS)玻璃掺杂的MnZn铁氧体.研究了CBS玻璃掺入量及烧结温度对MnZn铁氧体的烧结特性及磁性能的影响.结果表明:样品的密度随着CBS掺入量的增加而不断减小,磁性能随着温度的升高而不断增强;掺入适量CBS可在烧结时形成液相,使固体颗粒间产生液相烧结并促进晶粒的长大....     

过渡金属(Mn2+、Ni2+、Fe3+、Cu2+)掺杂ZnO基稀磁半导体的制备及性质

利用溶液腐蚀法制备了Mn2+、Ni2+、Fe3+、Cu2+离子掺杂的ZnO基稀磁半导体。XRD表明掺杂后的ZnO仍然保持单一的纤锌矿结构,没有任何杂质相产生。由紫外-可见光反射谱可知掺杂后吸收边发生了红移。掺杂前ZnO的带隙为3.20eV,对样品分别掺入Mn、Ni、Fe和Cu后的带隙分别为3.19eV、3.15eV、3.08eV和3.17eV。掺杂后样品的室温PL谱除了紫外发射峰外,对于Mn掺杂的样品还在蓝光区域出现了2个分别位于424nm和443nm的发射峰,Fe掺杂的样品出现了一个位于468nm的微弱发射峰,Cu掺杂的样品出现了位于469nm及535nm的很宽的发射峰。室温磁滞回线显示掺杂后样品有明显的铁磁性,掺入Mn、Ni、Fe和Cu样品的剩余磁化强度(Ms)分别为0.3902×10-3emu/cm3、0.454emu/cm3、0.372emu/cm3和0.962×10-3emu/cm3,矫顽力分别为47Oe、115.92Oe、99.33Oe和23Oe。经分析室温铁磁性来源于缺陷调制的Mn2+-Mn2+长程铁磁交换相互作用。     

Magnetic Properties of Y3Fe5O12 Nanoparticles Doped Bi and Ce Ions

Y_2.9-xCe_0.1Bi_xFe₅O₁₂ (x = 0-0.5) nanoparticles ranging from 58 to 63 nm were fabricated by a sol-gel method, and their crystallite structures and magnetic properties were investigated by X-ray diffraction (XRD), IR spectroscopy, and vibrating sample magnetometer (VSM). Results of VSM show that the saturation magnetization intensity increased with increase in Ce content (0.1), decrease in Bi concentration (x), and increase in particle size of the formulation.     

Evolution of Superconducting Properties of LiFeAs Single Crystals Doped with Magnetic or Nonmagnetic Impurities

The effect of magnetic Co²⁺ and nonmagnetic Ga³⁺ impurities on the crystal structure and superconducting properties of LiFeAs single crystals has been investigated. A large T _c decrease of about 4.8 K/at% is observed in Ga-doped LiFeAs. This rate is higher than that of the material doped with magnetic Co impurities (～3.7 K/at%). The greater T _c suppression in the Ga case is likely due to the pair breaking associated with the significant changes in the crystal structure of the doped material. The increase of the critical current densities in intermediate magnetic fields (H⊥?ab) indicates that a very small amount of Ga (0.5 at%) acts as an effective pinning site for flux pinning enhancement in the material. The analysis of the temperature and field dependencies of the magnetic relaxation is consistent with the collective pinning model for the Co-doped material, while the magnetic relaxation measurements combined with the peak position of the critical current density in the B–T phase diagram of Ga-doped LiFeAs suggest an elastic–plastic transition of the vortex lattice at higher temperatures and fields.