Synthesis of B4C nanobelts in porous SiC bodies

B4C nanobelts were synthesized in porous SiC bodies, which had a sponge structure. The interconnected pore size of the SiC bodies was around 600 microm. The raw materials used for the B4C nanobelts were B2O3 for boron and phenolic resin and carbon black for carbon. The nanobelts grew fully inside the porous SiC when heat treated at 1400 degrees C for 1 h using LiCl as a volatilizing agent and cobalt as a catalyst. The thickness of the rhombohedral B4C nanobelts ranged from 0.1 to 1 microm, and their width was 0.5 to 10 microm. The length of the grown B4C belts was up to several hundreds of micrometers, and their growth direction was [110]. These single crystal nanobelts did not show any structural defects such as stacking faults, steps and twins. The low temperature synthesis in this study is attributed for the clean surface. It is suggested that the nanobelts were nucleated by the VLS mechanism, and then grew by the VS mechanism.     

Structure and Magnetic Properties of S-doped Mn_3O_4/S Composited Nanoparticles and Mn_3O_4 Nanoparticles

Composited nanoparticles,consisting of Mn3O4,S-doped Mn3O4 and S,were synthesized by co-precipitation reaction and Mn3O4 nanoparticles were then obtained after removing the pure S from the composited nanoparticles.The Mn3O4-type phase with larger lattice constant a was formed by doping sulfur.At fixed temperatures below Curie temperature(TC),the magnetization of the S-doped Mn3O4/S composited nanoparticles was smaller than that of the Mn3O4 nanoparticles.The blocking temperature was 36.3 and 34.8 K for Sdoped Mn3O4/S composite and Mn3O4 nanoparticles,respectively.The anisotropy field of S-doped Mn3O4/S composite was determined to be about 55.3 kOe.     

Synthesis and photoelectric properties of V3O7 x H2O and V3O7, nanobelts

V3O7 x H2O nanobelts have been synthesized via a hydrothermal route. Monoclinic V3O7, nanobelts could be obtained by thermal decomposition of V3O7 x H2O nanobelts at 400 degrees C. The synthesized products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. It was found that the V3O7 x H2O is of orthorhombic phase and single crystalline nanobelts with width of 100-500 nm and length up to 100 microm. The formation mechanism of the V3O7 x H2O nanobelts was discussed. Light sensitivity in exposure to a simulated sunlight in different intensity and biases have been investigated on the electrode made from the V3O7 x H2O and V3O7, nanobelts. The results show that the photocurrent intensity of the V3O7 nanobelts is much larger than that of the V3O7 x H2O nanobelts. The fast current response has been observed under alternative control of light on and off at 2 s interval.     

Fe(3)O(4) nanobelts: one-pot and template-free synthesis, magnetic property, and application for lithium storage

We report on the synthesis of Fe(3)O(4) nanobelts with good magnetic properties and lithium storage performances by using a one-pot and template-free hydrothermal method with Na(2)CO(3) and FeCl(2) as the reactants. By controlling the amount of Na(2)CO(3), we obtained pure Fe(3)O(4) nanobelts with widths of 0.1-2?μm, thicknesses of about 10 nm and lengths of 20-30?μm, showing a high aspect ratio. XRD and SAED patterns of the obtained sample demonstrated that the Fe(3)O(4) nanobelts were well crystallized. Nitrogen adsorption/desorption measurements showed that Fe(3)O(4) nanobelts manifested a BET surface area of 25.04?m(2)?g(-1). Further experiments demonstrated that the amount of Na(2)CO(3) played an important role in controlling both the morphologies and crystal structures of the products. The formation mechanism of Fe(3)O(4) nanobelts was also studied. More importantly, we found that the Fe(3)O(4) nanobelts showed magnetic properties with a magnetic saturation value of 77.0?emu?g(-1) and lithium storage performances with a high initial discharge capacity of 1090?mAh?g(-1) at a current rate of 500?mA?g(-1), and a reversible capacity of 404?mAh?g(-1) retained after 60 charge/discharge cycles. These results suggest that the Fe(3)O(4) nanobelts might be promising for magnetic and lithium battery applications.     

Fabrication of photoluminescent S doped Y2O3:Eu3+ nanobelts

We have successfully fabricated the S doped Y(OH)3 nanobelts with 15-30 microm in length and 50-300 nm in width and S doped Y(OH)3:Eu3+ nanobelts with 4-15 microm in length and 80-500 nm in width (most between 100 and 200 nm) via a similar process for preparation of Y(OH)3 nanotubes. Photoluminescent (PL) nanobelts of S doped Y2O3:Eu3+ were obtained through dehydration of the S doped Y(OH)3:Eu3+ nanobelts at 450 degrees C in N2. The PL properties of the S doped Y2O3:Eu3+ nanobelts have been studied and evidenced that we have successfully synthesized functional S doped Y2O3:Eu3+ nanobelts with interesting photoluminescence properties.     

Y掺杂Mn3O4/石墨烯复合材料的电化学性能

通过水热法在不同反应温度、一定反应时间条件下制备用于超级电容器的Mn3O4,同时实现Y的掺杂和复合石墨烯。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和电化学工作站对样品的形貌、结构与电化学性能进行分析,发现其与标准PDF卡89-4837相吻合,为单一相的Mn3O4,属四方晶系,空间群为I41/amd(No.141)。所制得Mn3O4为棒状颗粒。Y掺杂含量为5%时Y-Mn3O4的比电容可以达到89 F·g^-1,Y-Mn3O4/石墨烯复合材料的比电容可达到267F·g^-1,并且它们的循环伏安曲线为矩形形状,说明Y的掺杂和石墨烯的负载协同提高了Mn3O4的电化学性能。     

A room temperature synthetic route to Mn3O4 nanoplates

Nanoplates of Mn3O4 were prepared by redox reactions of Mn(CH3COO)2 x 4H2O taking place in short chain n-alkylamine aqueous solutions such as n-butylamine, n-propylamine and n-hexylamine at room temperature. Phase purity was confirmed by powder X-ray diffraction. The high resolution transmission electron microscopy revealed the rectangle shape of Mn3O4 nanoplates with the average edge length of 22 nm and width of 19 nm. The prepared Mn3O4 nanoplates exhibited a coercive field of 5034 Oe at 10 K. The possible formation mechanism was also discussed.     

Structural in situ study of the thermal behavior of manganese dioxide materials: toward selected electrode materials for supercapacitors

The thermal behavior of a series of MnO2 materials was investigated toward MnO2 microstructures under inert atmospheres. The byproduct formed during MnO2 heat treatments from the room temperature to 800 °C were characterized by in situ X-ray diffraction analyses. It was found that annealing spinel and ramsdellite phases caused the formation of MnO2 pyrolusite at 200 °C, Mn2O3, at 400 °C, and then Mn3O4 at higher temperatures. In the case of cryptomelane and birnessite phases, the heating process resulted in the formation of K0.51Mn0.93O2 at 600 °C, while Mn3O4 was also formed and still present up to 800 °C. Heat-treating Ni-todorokite and OMS-5 up to about 450 °C led to the formation of NiMn2O4 and NaxMnO2, respectively, and again Mn3O4 at higher temperatures. All of these structural transformations were correlated to resulting weight losses of MnO2 powders, measured by thermogravimetric analyses, during the heating process. Cyclic voltammetry measurements were performed in the presence of 0.5 M K2SO4 aqueous solution for annealed cryptomelane, K0.51Mn0.93O2, and Mn3O4-based electrodes. It was found that MnO2 cryptomelane is electrochemically stable upon heating. The long-term charge/discharge voltammetric cycling revealed that the specific capacitance of Mn3O4-based electrode is significantly improved from 14 F·g(-1) (after 20 cycles) to 123 F·g(-1) (after 500 cycles).     

Vanadium pentoxide nanobelts and nanorolls: from controllable synthesis to investigation of their electrochemical properties and photocatalytic activities

Uniform V(2)O(5)· xH(2)O nanobelts with high aspect ratios and ultra-long V(2)O(5)· xH(2)O nanorolls with novel scroll-like structures were synthesized on a large scale by a simple hydrothermal growth route using NH(4)VO(3) as the raw material in the presence of different acids at 180?°C for 24?h. Their morphologies were observed by scanning electron microscopy (SEM). X-ray powder diffraction measurement and thermal gravimetric analysis revealed the composition of nanobelts and nanorolls to be V(2)O(5)·0.9H(2)O and V(2)O(5)·0.6H(2)O, respectively. The possible mechanisms of formation of the nanobelts and nanorolls were schematically elucidated based on the layered structure of vanadium pentoxide. In addition, corresponding anhydrous V(2)O(5) nanostructures with better crystallinity were obtained by calcining the precursors of V(2)O(5)·0.9H(2)O nanobelts or V(2)O(5)·0.6H(2)O nanorolls. Furthermore, we have investigated the electrochemical intercalation properties with Li(+) and the photocatalytic activities of the synthesized V(2)O(5)·0.9H(2)O nanobelts, V(2)O(5)·0.6H(2)O nanorolls and their corresponding post-annealing products. It was observed that the morphologies and compositions of the synthesized products had an evident influence on the electrochemical intercalation properties with Li(+) and photocatalytic activities.     

Preparation of a new nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome and its antitumor effect on MDA_MB_231 cells

The purpose of our research is to explore the preparation method of a new nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome and study its antitumor effect on MDA_MB_231 cells. The liposomes prepared by the method of rotatory film and high-pressure homogenization were detected by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), nano-particles detector, atom fluorescence spectrophotometer and differential scanning calorimetry (DSC). The therapeutic effects of the nanosized thermosensitive magnetoliposomes combined hyperthermia on human MDA_MB_231 cells in vitro were evaluated by MTT assay and flow cytometry assay. The results indicated that the nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposomes were prepared successfully. The liposomes were spherical, and most of them were single-room. The exat average diameter of them was 103.8 nm. EDS showed each nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposome contained P, Mn, Zn, Fe, and As elements, and this proved liposomes have successfully entrapped As2O3 and Mn0.5Zn0.5Fe2O4. The encapsulation ratio of As2O3 detected by atom fluorescence spectrophotometer was 82.16%. The result of heating test showed that Mn0.5Zn0.5Fe2O4 can serve as a heating source upon alternating magnetic field (AMF) exposure leading the nanosized thermosensitive liposomes to reach its phase transition temperature (42.52 degrees C) and release As2O3. MTT assay and flow cytometry assay revealed that the therapeutic effect of the nanosized As2O3/Mn0.5Zn0.5Fe2O4 thermosensitive magnetoliposomes combined with hyperthermia upon AMF on MDA_MB_231 cells was much better than other groups.     

Silicon-induced oriented ZnS nanobelts for hydrogen sensitivity

Oriented ZnS nanobelts were grown on an Si substrate using hydrogen-assisted thermal evaporation under moist gas conditions. It was found that these ZnS nanobelts had a single crystal hexagonal wurtzite structure growing along the [0001] direction. They had a rectangular cross section with lengths of up to tens of micrometres, a typical width of 50-150 nm, and a thickness of ～40?nm. A silicon-induced vapour-liquid-solid process was proposed for the formation of the ZnS nanobelts and their assembly. These oriented nanobelts have much faster response time to hydrogen gas than that of pure ZnO and Pd-sensitized ZnO, showing excellent hydrogen sensing properties.     

无模板剂水热合成Bi12O17Cl2纳米带及其阻燃性能研究

以β-Bi2O3为原料,采用无模板剂水热法制备了Bi_(12)O_(17)Cl_2纳米带,利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和高分辨透射电镜(HRTEM)对其形貌和结构进行了表征并作为阻燃剂添加到聚氯乙烯(PVC)中评价其阻燃性能。结果表明,适宜的Bi/Cl物质的量比对水热合成Bi_(12)O_(17)Cl_2纳米带及其化学计量比影响显著,当Bi/Cl物质的量比为1∶2.5时,可得到分散性好、形貌均匀的Bi_(12)O_(17)Cl_2纳米带;改变Bi/Cl物质的量比,纳米带中Bi/Cl化学计量比从6∶1变成2.4∶1。初步探讨了Bi_(12)O_(17)Cl_2纳米带可能的生长机理,在水热反应过程中,Bi 3+与Cl-发生络合反应形成BiCln3-n络合物,从而合成Bi_(12)O_(17)Cl_2纳米带。     

掺杂Fe3+对高电压正极材料LiNi0.5Mn1.5O4结构和性能的影响

以Li2CO3、MnO2、NiO、FeC2O4·2H2O为原料,用高温固相法合成了尖晶石结构的LiNi0.5Mn1.5O4/LiNi0.5Mn1.45Fe0.05O4锂离子电池正极材料;并对合成的样品进行XRD、SEM及电化学性能测试。结果表明:引入Fe3+可以提高材料的结构稳定性,并且改善了材料的导电性,一定程度上减缓材料的容量衰减,LiNi0.5Mn1.45Fe0.05O4表现出较好的电化学性能,0.2C倍率下经20次充放电循环,未掺杂样品与掺杂样品的放电比容量分别为115.4mAh/g和120.1mAh/g,容量保持率由92.1%提高到96.5%。     

Facile synthesis of MnV2O6 nanostructures with controlled morphologies

MnV₂O₆ nanostructures including nanorods, nanobelts, and nanosheets, have been synthesized by a facile hydrothermal reaction between Mn(CH₃COO)₂·4H₂O and commercial V₂O₅. The synthesized products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The influences of synthetic parameters, such as, reaction time, temperature and medium, on the morphologies of the resulting products have been investigated. As the reaction temperatures increase from 120 °C to 180 °C, MnV₂O₆ nanorods and nanobelts are obtained, respectively. The time-dependent experimental results at 180 °C reveal that the sizes of MnV₂O₆ nanobelts increase gradually with the reaction proceeding. Interestingly, as the reaction is carried out with the aid of H₂O₂ solution, flower-like MnV₂O₆ nanosheets are formed.     

二甲基亚砜介质中纳米Mn3O4的合成

以乙酸锰为原料，采用简单的溶剂热法在二甲基亚砜和水的溶液中合成出尺寸只有数纳米的Mn3O4颗粒，对样品进行了FT—IR、XRD、TEM等表征．XRD衍射峰显示产物物相为Mn3O4．磁性能测试结果表明这种纳米材料室温下表现为顺磁性．     

面向对象的制造系统过程建模方法的研究

在分析了面向对象Ｏ－Ｏ技术在过程建模中的优点的基础上,采用Ｏ－Ｏ技术定义了企业过程对象类结构,并在此基础上建立了面向对象的企业过程模型结构２,这一模型结构通过企业过程对象将企业的组织,活动和资源全面集成。     

Temperature effect on electrospinning of nanobelts: the case of hafnium oxide

Electrospinning is a convenient and versatile method for fabricating different kinds of one-dimensional nanostructures such as nanofibres, nanotubes and nanobelts. Environmental parameters have a great influence on the electrospinning nanostructure. Here we report a new method to fabricate hafnium oxide (HfO(2)) nanobelts. HfO(2) nanobelts were prepared by electrospinning a sol-gel solution with the implementation of heating and subsequent calcination treatment. We investigate the temperature dependence of the products by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and energy-dispersive x-ray (EDX) spectroscopy. The heating temperature of spinning ambient is found to be crucial to the formation of HfO(2) nanobelts. By tuning the temperature, the morphological transformation of HfO(2) from nanowires to nanobelts was achieved. It was found that the rapid evaporation of solvent played an important role in the formation process of HfO(2) nanobelts. It is shown that nanobelts can only be obtained with the temperature higher than 50?°C and they are in the high quality monoclinic phase. A possible growth mechanism of the nanobelts based on phase separation is proposed. The enhanced photoluminescence (PL) of HfO(2):Eu(3+) nanobelts is also illustrated.     

Luminescence properties of nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors

Ba3MgSi2O8:Eu2+, Mn2+ phosphors were synthesized by the sol-gel method and high temperature solid-state reaction method, respectively. XRD (X-ray diffraction), FT-IR (Fourier transform infrared spectroscopy), PL (photoluminescence spectra), and PLE (photoluminescence excitation spectra) were measured to characterize the samples. Emission and excitation spectra of our Ba3MgSi2O8:Eu2+, Mn2+ phosphors monitored at 441, 515, and 614 nm are depicted in the paper. The emission intensities of 441 and 515 nm emission bands increase with increasing Eu2+ concentration, while the peak intensity of the 614 nm band increases with increasing Mn2+ concentration. We conclude that the 515 nm emission band is attributed to the 4f(6)5d transition of Eu2+ ions substituted by Ba2+ sites in Ba2SiO4. The 441 nm emission band originates from Eu2+ ions, while the 614 nm emission band originates from Mn2+ ions of Ba3MgSi2O8:Eu2+, Mn2+. Nano-crystalline Ba3MgSi2O8:Eu2+, Mn2+ phosphors prepared by the sol-gel method show higher color rendering and better color temperature in comparison with the samples prepared by high temperature solid-state reaction method.     

(La2/3Ca1/3)(Mn(3-x)/3)Fex/3)O3体系磁电阻行为的研究

通过系统地测量（La2/3Ca1/3）（Mn（3-x）／3Fex／3）O3（x＝0、0.1、0．2、0．3的体系样品的电阻率-温度关系以及一定温度下磁电阻率与磁场的关系,发现随x的变化其磁电阻率峰和电阻率峰均发生位移,磁电阻率峰值增大,并伴生磁电阻率峰展宽效应．作者认为由于Fe的替代,引起体系中Mn3 ／Mn4 比率及磁矩的变化,加之外场对磁有序结构的调制作用,从而影响了Mn3 －O－Mn4 的双交换作用,最终导致磁电阻行为发生变化．     

The effects of gallium droplets on the morphologies and structures of alpha-Fe2O3 nanostructures grown on iron substrates

Alpha-Fe2O3 nanowires and nanobelts were grown by the thermal oxidation of iron substrates with or without gallium droplets in the air. The nanowires and nanobelts show a bicrystal structure with the growth direction uniformly along [110]. The morphological and structural properties of the as-grown alpha-Fe2O3 nanostructures are described and the growth condition dependence of the alpha-Fe2O3 nanostructures is shown. The transformation from nanowires to nanobelts occurs with the increase of growth temperature and addition of gallium. In addition, the growth evolution is investigated with reference to the Fe surface diffusion and supersaturation.