Synthesis and properties of the modification of micro-crystal LiMn2−x Al x O4 cathode material for Li-Ion batteries

The micro-single crystal material spinel LiMn2-xAlxO4 was prepared by a sol-gel procedure and modified by alumina; the electrochemical measurements show that the performances and characteristics of modified LiMn2-xAlxO4 electrode material are better than those of LiMn2O4. Hence, the modified LiMn2-xAlxO4 is a good cathode material for lithium batteries. This can be explained that the size of the modified particle is larger than that of unmodified material, so electrons can be easily transported between the particles.     

Preparation, characterizations and magnetic properties of doped barium hexaferrites BaFe12-2x Mn x Sn x O19 (x = 0.0–1.0)

A series of doped barium hexaferrites BaFe12-2xMnxSnxO19 (x = 0.0-1.0) particles were prepared by the co-precipitation/molten salt method. The particle size and crystalline of the samples BaFe12-2xMnxSnxO19 decrease with an increase in the doping amount x. When x is less than 0.8, the pure BaFe12-2xMnxSnxO19 particles with hexagonal plate morphology are obtained. The effects of substitution on magnetic properties were evaluated and compared to nomal BaFe12O19. The specific magnetizations (Ms) of doped materials have been significantly improved. Among all these compositions, the BaFe10.4Mn0.8Sn0.8O19 sample has the highest Ms value of 81.8 A?m2?kg-1 at room temperature and its intrinsic coercivity (Hc) is 44.5 kA?m-1. The as-prepared doped barium ferrites exhibit a low temperature coefficient of coercivity close to zero. The coercivity is independent of temperature when x is in the a range 0.5-0.7.     

Proposal and achievement of a relatively Al-rich interlayer for In-rich Al x In1−x N films deposition

Ternary In-rich Al _x In_1?x N films were successfully grown on Si (111) and (0001) sapphire substrates by radio-frequency magnetron sputtering on a relatively Al-rich Al _x In_1?x N layer after AlN buffer. X-ray diffraction (XRD) patterns of the films indicate highly c axis-oriented wurtzite structure and the indium content of about 0.76 has been evaluated according to the Vegard’s law. An Al-rich Al _x In_1?x N transition layer was formed between the ultimate In-rich Al _x In_1?x N film and the AlN buffer, which served as a further buffer to alleviate mismatch. X-ray photoelectron spectroscopy (XPS) depth profiling analyses confirm the alternative of indium and aluminum composition and the unavoidable oxygen impurities from surface to bulk. Owing to high indium content, obvious E ₂ ^H and InN-like A ₁ (LO) phonon model accompanying with slight AlN-like A ₁ (LO) phonon model are observed. Hall effect measurements demonstrate n-type electrical conductivity in these alloys with carrier concentrations n=10¹⁹ cm^?3. The strain in In-rich Al _x In_1?x N films can be significantly reduced by introducing an Al-rich interlayer, facilitating the improvement of film quality for diverse device applications.     

Direct synthesis of Zn1−x Cd x S (0⩽x⩽1) quantum dots in aqueous solution and application in biology

A simple procedure was presented to directly synthesize Zn1-xCdxS (0≤x≤1) quantum dots (QDs) in aqueous solution. QDs’ structures and properties were characterized by TEM (transmission electron microscopy), XRD (X-ray diffraction) and fluorescence microscopy. For those as-synthesized Zn1-xCdxS QDs, when the molar ratio between Zn and Cd changed from 1 to 0, its photoluminescence (PL) emission peak shifted from 430 nm to 675 nm. PL emission quantum efficiency was up to 15%. The experiment results demonstrated that those alloyed QDs showed a good biocompatibility and could be used as labelling materials in cell biology.     

Effect of Zn2+ content on the microstructure and magnetic properties of nanocrystalline Ni1−x Zn x Fe2O4 ferrite by a spraying-coprecipitation method

Nanocrystalline Ni1-xZnxFe2O4 ferrites with 0≤x≤1 were successfully prepared by a spraying-coprecipitation method.The microstructure was investigated by using XRD and TEM.Magnetic properties were measured with vibrating sample magnetometer(VSM) at room temperature.The results show that the grain size of nanocrystalline Ni1-xZnxFe2O4 ferrite calcined at 600 ℃ for 1.5 h is about 30 nm.Lattice parameter and specific saturation magnetization Ms of nanocrystalline Ni1-xZnxFe2O4 ferrite increase with the Zn2+ ions content at room temperature,and maximum Ms is 66.8 A·m2·kg-1 as the Zn2+ ions content is around 0.5,and coercivity Hc of the nanocrystalline Ni1-xZnxFe2O4 ferrite decreases with Zn2+ ions content.     

The microstructure and properties of Ag(Nb0.8Ta0.2)1−x (Mn0.5W0.5) x O3 ceramic system

The microstructure and dielectric properties of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3(x=0,0.04,0.08,0.12,0.16) ceramic system were investigated.The Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramics were prepared by the traditional solid-state reaction method and were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and Raman spectrometer.The sintering ability and dielectric properties of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 were found to be improved with the doping of Mn4+ and W6+ ions.The densification temperature of Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramics decreased from 1 080 ℃ to 1 000 ℃ when x increased from 0 to 0.16.Ag(Nb0.8Ta0.2)1-x(Mn0.5W0.5)xO3 ceramic was found to have the best dielectric properties when x=0.08,larger permittivity(■=547) and smaller dielectric loss(tan■=0.00156).     

Hydriding and dehydriding kinetics of nanocrystalline and amorphous MgzNi1-xMnx （x=0-0.4） alloys prepared by melt spinning

A partial substitution of Ni by Mn was implemented in order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys.The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xMnx(x=0,0.1,0.2,0.3,0.4) alloys were synthesized by the melt-spinning technique.The structures of the as-cast and spun alloys were studied by X-ray diffractometry(XRD),scanning electron microscopy(SEM) and high resolution transmission electron microscopy(HRTEM).The hydrogen absorption and desorption kinetics of the alloys ...     

Comparison of Conventional and Microwave-assisted Synthesis and Characteristics of Aluminum-pillared Rectorite

The synthesis and characterization of aluminum-pillared rectorite were studied. The synthesis was conducted with both conventional heating and microwave irradiation. Microwave irradiation was found to enhanee the intercalation and ion-exchange during synthesis, and to be able to produce the rectorite with a larger d001 aad a better uniformity. The specific surface area is 180 m^2 / g and basal spacing is 3.2 nm.The texture change and thermal and hydrothermal stability of cross- linked rectorite were examined using XRD, FTIR, nitrogen-adsorption and TGA. The experimental results show that the aluminum-pillared rectorite, after calcined at 800℃ for 3 hours, can keep the basal aluminum-silicate texture and would not disperse in water at room or an elevated temperature. The alumimum-pillared rectorite shows a high specific surface area, good thermal and hydrothermal stability, and is promising in applications as catalyst carriers and adsorbents for waste treatment.     

Structural Characteristics of Paleozoic and Geological Significance of Oil and Gas of Dongpu Depression

The Dongpu depression along the Yellow Riveron the boundary of Shandong and Henan provinces,across Puyang,Kaifeng,Xinxiang,Heze,andLiaocheng,is a small depression in a series of Ceno-zoic rift valley basin on North China Tectonic Platein eastern China.As one of the depressions insouthern Linqin depression in Bohai Bay basin,theDongpu depression belongs to part of the NorthChina Cenozoic rift valley basin[1] .With the strikeof NNE,the depression is lute shaped,narrow( 1 4— 1 6km) in …     

Electrical and Magnetic Properties of Electron Doped BixCa1-xMnO3 （0〈x ≤0.33） Ceramics

Measurements of crystal structures, electrical and magnetic properties for the electron doped BixCa1-xMnO3 （0〈x≤〈0.33） reveal the presence of a variety of notable changes in correlation with magnetic transitions and charge ordering. Samples with x〈0.2 in general show a clear ferromagnetic transitions around 130 K. On the other hand, samples with 0.2≤x≤0.33 show much more complex low-temperature magnetic properties perhaps due to the coupling between the magnetic states and orbital/charge ordering. Structural transformations and structural modulations in the x=0.25 and 0.33 samples have been observed by transmission electron microscopy.     

Analysis of Physical and Chemical Characteristics and Influence Factors of UCG

Based on the UCG (underground coal gasification) theory, the “three zones“ which are oxidization zone,reduction zone, and drying zone, were divided; physical and chemical properties of each zone were analyzed. Factors, such as temperature, rate of water pouring, quanzity of air blast, thickness of coal seam, and the operation pressure were discussed. Among the influencing factors, the temperature is the most important one.     

Experiment and mechanism of vibration liquefaction and compacting of saturated bulk solid

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Characteristics and Mechanism of Scrooping Sound of Silk

In this study a measurement instrument of scrooping sound has been develope.Thefollowing results were obtained by means of measurement and analysis for the frequencyspetrums of scrooping sound of silk : 1 The scrooping vibration is mainly composed of S- S( stick-slip vibration) ,F- V(free damping vibration) and S- C( characteristic high frequency vibration) vibrations. 2 The scrooping sound of silk mainly depends on F- V and S- S vibrations and be-longs to lower frequency sound,while the effect of S- C vibration is limited. 3 The wave and the vibration equations as well as some fromulas of relative physicalproperties have been established on the discussion about the stick- slip vibration. 4 The critical condition producing stick- slip vibration is( μs- μd)> 0.     

Growth and microstructure of AlN whiskers and dendrites

AlN whiskers or dendrites were synthesized with a sublimation-recrytallization method by using Al,AlN powders and some additives as raw materials.Whiskers with different sizes that featured high purity and good crystallinity were obtained by controlling temperature and gas supersaturation in the reaction container,The whiskers were described as long and straight single crystals of approximately 1-30 um in diameter by the centimeter range in length.However,AlN dendrites were about 1mm in diameter by 0.5cm in length,and showed an obviously preferential growth orientation.i.e.,perpendicular to [211] and [1011] planes.It is concluded that the whiskers or dendrites grow via the vapor-solid mechanism.     

Effect of pH and temperature on acidogenic and hydrogenic activities of glucose-degrading bio-granules

0　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓｉｔｂｅｃｏｍｅｓｉｎｃｒｅａｓｉｎｇｌｙｃｌｅａｒｔｈａｔｔｈｏｓｅｃｏｎｖｅ ｎｉｅｎｔｅｎｅｒｇｙｓｏｕｒｃｅｓ ,ｓｕｃｈａｓｏｉｌａｎｄｇａｓ,ｃａｎｎｏｔｓｕｐ ｐｏｒｔｔｈｅｗｏｒｌｄｆｏｒｅｖｅｒ .Ｍａｎｈａｓｂｅｇｕｎｔｏｔｕｒｎｔｏｆｉｎｄｔｈｅａｌｔｅｒｎａｔｉｖｅｓ[1] .Ｗｉｔｈｔｈｅｇｒｏｗｉｎｇｃｏｎｃｅｒｎｓｏｎｔｈｅｇｒｅｅｎｈｏｕｓｅｅｆｆｅｃｔｉｎ 1990ｓ ,ｈｙｄｒｏｇｅｎｈａｓｂｅｅｎｒｅｃｏｇ ｎｉｚｅｄａｓａｎｉｍｐｏｒｔａｎｔｆ…     

Ventilation of indoor formaldehyde and estimation of its emission and air exchange rate

With continuous development of economy,im-provement of living conditions and inhabitation environ-ment,the public consciousness of environmental pro-tection has been raised and more attention has beenpaid to indoor air quality.Because formaldehyde aswell …     

Journal of University of Science and Technology Beijing

This journal provides an international medium for the publication of theoretical and experimental studies related     

Synthesis and characterization of mibolerone

A simple and effective route for the synthesis of mibolerone was described starting from the estr-5(10)-en-3,17-dione in four steps with the overall yield of 47.0 %.Thus,two methods for key intermediate methylnorandrost were investigated:one(method A)starting from estr-4-en-3,17-dione underwent 3-keto group protected with ethyl orthoformate to give 3-ethoxy-3,5-dien-estr-17-one,the other(method B)from estr-5(10)-en-3,17-dione and protected 3-keto group to give 3,3-dimethoxy-estr-5(10)-7-one in a mild acidic condition.Then,two intermediates were subsequently reacted with methyllithium followed by a mild hydrolytic procedure and gave methylnorandrost with total yield 25.0% and 86.0 %,respectively.In the preparation of 6-dehydrogenation product of methylnorandrost,two procedures(method C and method D)were investigated:one was the protected 17α-methyl-17β-hydroxy 3,5-enol ethers estrendiene brominated and the resulting 6-bromo-19-methylnortestosterone was then immediately dehydrohaloenated to give 6-dehydro-19-methylnortestosterone,the total yield only reaches 36.0%;the other was directly dehydrogenated with chloranil and the yield reaches 75.6% under the optimum conditions:in refluxing tetrahydrofuran,the molar ratio of methylnorandrost to chloranil is 0.66 and reaction time of 5 h.The titled compound and intermediates were characterized by 1H and 13C NMR,IRMS and elemental analysis.     

Journal of University of Science and Technology Beijing

This journal provides an international medium for the publication of theoretical and experimental studies related to the fields of Mineral, Metallurgy and Materials. Papers dealing with mineral processing, mining, mine safety, environmental pollution and protection of mines, process metallurgy, metallurgical physical chemistry, metals working, structure and physical properties of materials, corrosion and resistance of materials, are viewed as suitable for oublication.     

Electronic Structures and Chemical Bonds of Cobaltite and Ni-Doped

The relation among electronic structure, chemical bond and thermoelectric property of Ca3 Co2 O6 and Ni-doped was studied by density function theory and discrete variation method（DFT-DVM）. The results indicate that the highest valence band（ HVB ）attd the lowest conduction band（ LCB ） are mainly attribuled to Co3d, Ni3d and O2p atomic orbitals. The property of a semiconductor is shown from the gap between HVB and LCB. The gap of Ni-doped one is less than that of Ca3 Co2 O6. The non-metal bond or ceramic characteristic of Ni-doped one is weaker than that of Ca3 Co2 O6, but the metal characteristics of Ni-doped one are stronger than those of Ca3 Co2 O6. The thermoelectric property should be improved by adding Ni element into the system of Ca3 Co2 O6 .