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1.
Uniform capsule‐like α‐Fe2O3 particles were synthesized via a simple hydrothermal method, employing FeCl3 and CH3COONa as the precursors and sodium dodecyl sulfate (SDS) as soft template. X‐ray powder diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and high‐resolution transmission electron microscopy were used to characterize the structure of synthesized products. Some factors influencing the formation of capsule‐like α‐Fe2O3 particles were systematically investigated, including different kinds of surfactants, the concentration of SDS, and reaction times. The investigation on the evolution formation reveals that SDS was critical to control the morphology of final products, and a possible five‐step growth mechanism was presented by tracking the structures of the products at different reaction stages.  相似文献   

2.
Uniform Co3O4 nanorods were prepared by a micelle-assisted hydrothermal method. The samples were characterized by scanning electron microscopy (SEM), energy disperse spectra (EDS), transmission electron microscopy (TEM), selected area electron diffraction (ED), X-ray diffraction (XRD), and N2 adsorption. The chemoluminescence and catalytic oxidation properties of CO and CH4 over Co3O4 nanorods were investigated. The results showed that the micelles played a key role in the formation of uniform nanorods, that the nanorods with a high crystallinity were obtained after being treated hydrothermally, and that the nanorods showed a higher chemoluminescence (CL) intensity of CO oxidation and a higher activity for CH4 combustion than the bulk one. The adopted ‘one-pot’ synthesis is a facile method, since no further annealing at high temperatures is needed.  相似文献   

3.
Octahedral Fe3O4microcrystals were synthesized using a triethanolamine‐assisted route under hydrothermal conditions. The chemical compositions and morphologies of the as‐prepared samples were characterized in detail by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). During the hydrothermal process for the preparation of Fe3O4 octahedra, the possible mechanism was discussed to elucidate the formation of the octahedral Fe3O4microcrystals. Triethanolamine and hydrazine hydrate play important roles in the formation of the final products. The magnetic property of sample was evaluated on a vibrating sample magnetometer (VSM) at room temperature. The values of saturation magnetization and coercivity of octahedral Fe3O4are about 103 emu/g and 157 Oe, respectively. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
Dendrite and platelet‐like α‐Fe2O3 microcrystals were synthesized by the oxidation reaction of K4Fe(CN)6and NaClO3 through a simple hydrothermal method. The structures and morphologies of the as‐prepared samples were characterized in detail by X‐ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The experiment results show that NaOH played an important role in controlling the morphology of the final products. The possible mechanism was discussed to elucidate the formation of different morphologies of the α‐Fe2O3 microstructures. Besides, the magnetic property of the dendrite α‐Fe2O3 microstructure was characterized by a vibrating sample magnetometer (VSM). (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

5.
Monoclinic peanut‐like BiVO4 products have been successfully synthesized by a solvothermal method. The volume of CH3COOH and the concentration of NH3·H2O were found to play important roles in the formation of this morphology. The optimal condition for preparation of highly active peanut‐like BiVO4 samples are the volume of CH3COOH, which was 5 ml, and the concentration of NH3·H2O, which was 2 mol/L. The as‐prepared samples were characterized by XRD, SEM, TEM, DRS, BET, and their photocatalytic activity was evaluated by photocatalytic decolorization of a Rhodamine B (RhB) aqueous solution under visible‐light irradiation. The results demonstrated that BiVO4 with peanut‐like morphology was better than that of other BiVO4 samples for photodegradation of RhB.  相似文献   

6.
Cobalt tungstate (CoWO4) nanocrystals with an average size of 20–50 nm were synthesized via a template‐ or surfactant‐free hydrothermal route. The crystal structure and morphology of the as‐synthesized CoWO4 sample were characterized by X‐ray diffraction, scanning electron microscopy and transmission electron microscopy. Magnetic measurements on the as‐synthesized CoWO4 nanocrystals indicate a Néel temperature (TN) of ∼40 K. This lower TN may be a result of the nanostructured particles that reduce the exchange coupling. The new synthetic route presented in this paper has potential applications to fabricate other metal tungstates (MWO4) materials.  相似文献   

7.
Nd(OH)3 particles of nanometer size have been prepared by using different methods. The obtained neodymium hydroxide samples have been investigated by using the FT-Raman spectroscopy, X-ray diffraction, transmission electron microscopy as well as field emission electron microscopy. Observable changes in enhanced electronic Raman bands have been found among the FT-Raman spectra of different morphological Nd(OH)3 particles which formed under different physical–chemical conditions. The result suggests that the change of size and morphology of Nd(OH)3 particles occur with structural change and subtle variation on the coordination environment around the neodymium ions.  相似文献   

8.
Spindle‐shaped α‐FeOOH nanocrystals were facilely synthesized using a poly (vinyl pyrrolidone) (PVP)‐assisted route under hydrothermal conditions. The chemical compositions and morphol‐ogies of the as‐prepared samples were characterized in detail by X‐ray power diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The experimental results reveal that these spindle‐shaped α‐FeOOH nanocrystals have self‐organized into assemblies with hierarchical nanostructures. The crucial roles of PVP in the hydrothermal synthesis of hierarchical α‐FeOOH nanostructures were discussed. The possible formation mechanism was also suggested. Moreover, the spindle‐shaped α‐Fe2O3 nanocrystals could be easily obtained after calcining the α‐FeOOH prepared by the PVP‐assisted hydrothermal process. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

9.
Well‐crystallized pure perovskite bismuth ferrite (BiFeO3) powders with various morphologies have been synthesized by a novel sol‐gel‐hydrothermal route for the first time, which combined the conventional sol‐gel process and the hydrothermal method. The as‐prepared samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and ferroelectric test system. The results revealed that the compositions, morphological and dimensional changes in bismuth ferrite samples synthesized by sol–gel–hydrothermal method strongly depend on the concentrations of mineralizer. Ferroelectric hysteresis loops are displayed in the BiFeO3 samples. The bismuth ferrites were hydrothermally synthesized at as low a temperature as 180 °C, which is comparatively lower than that synthesized by the normal sol–gel route. The formation mechanism of the bismuth ferrite crystalline was also discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
The formation of Ru microspheres by hydrothermal treated method in tungstosilicate acid (H4SiW12O40, TSA) solution is described. The particles are characterized by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM), respectively. The growth process of these microspheres has been examined. The results show that it is possible to synthesize and assemble other noble metal particles with unique superstructure. The characteristic catalytic behavior of the Ru microspheres is established by studying the decolorization of cango red in the presence of UV light. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

11.
Zinc sulfide (ZnS) microspheres were synthesized by a self‐template hydrothermal route using thiourea as sulphur source. The formation of these hollow spheres was mainly attributed to the oriented aggregation of ZnS nanocystals around the gas‐liquid interface between gas (H2S, NH3, or CO2) and water followed by an Ostwald ripening process. The gas bubbles of H2S, NH3, or CO2 produced during the reaction might play a soft‐template to form ZnS hollow microspheres. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), electron diffraction (ED), and photoluminescence (PL). The crystal structure of prepared ZnS microspheres is hexagonal phase polycrystalline. The average microspheres diameter is 1.5 ‐ 6 µm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

12.
Glass–ceramics with the composition 2Fe2O3.1ZnO.1MgO.96SiO2 [4ZnMgFe] and 2Fe2O3.2ZnO.3MgO.93SiO2 [7ZnMgFe] (mol%) were prepared using the sol–gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), electron diffraction (ED) and Mössbauer spectroscopy (MS) were used to investigate the glass–ceramics structure. The samples contain ferrite nanoparticles embedded in a glass matrix. However, zinc ferrite nanoparticles seems to be the preferential crystalline phase formed. The amount of ferrite particles depends on treatment temperature and sample composition. The Mössbauer spectroscopy measurements show that ferrite nanoparticles can exhibit a ferrimagnetic behaviour combined with superparamagnetism.  相似文献   

13.
Single‐crystalline dilead pentaoxochromate (Pb2CrO5) with nanorod‐shape has been synthesized by adjusting the pH value of the catanionic reverse micelles formed by a cationic surfactant CTAB (hexadecyltrimethylammonium bromide) and an anionic surfactant SDS (sodium dodecyl sulfonate), followed by a hydrothermal process. The results show that reaction parameters play important roles in the formation of the single‐crystalline Pb2CrO5. The reaction parameters include the kinds of the surfactants, the molar ratio (r) between the mixed cationic and anionic surfactants, reaction time and temperature. The as‐synthesized products are characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM) and powder X‐ray diffraction (XRD). (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

14.
《Journal of Crystal Growth》2003,247(3-4):419-424
Nanocrystalline potassium niobates (KNbO3, KNb3O8 and K4Nb6O17) of different morphologies were synthesized with the low-temperature hydrothermal method by adjusting the alkalinity of the reaction system. A possible formation mechanism of the nanocrystalline niobates was proposed based on the experimental results. All of the products were characterized with X-ray powder diffraction and transition electron microscopy. The Fourier transform (FT) infrared, FT-Raman and UV–VIS properties of the niobates were studied.  相似文献   

15.
Flower‐like self‐organized crystalline ZnO architectures were obtained through a facile and controlled hydrothermal process. As‐synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), X‐ray diffraction (XRD), electron diffraction and UV‐Vis spectroscopy. XRD and electron diffraction results confirmed the obtained materials are pure wurtzite ZnO. The effects of different ratios of starting materials and solvent on the morphologies of ZnO hydrothermal products were also evaluated by SEM observations. It is suggested that the use of water, rather than ethanol as the solvent, as well as employing a precursor of Zn(Ac)2 and 2NaOH (v/v) in hydrothermal reactions are responsible for the generation of specific flower‐like self‐assembled ZnO structures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

16.
纳米ZnO的形态控制及其发光性能   总被引:5,自引:2,他引:3  
以醋酸锌为原料,以聚合物和表面活性剂为添加剂,水热法合成了两种新型的纳米ZnO结构.并采用X射线衍射(XRD)、透射电镜(TEM)和高分辨透射电镜(HRTEM)以及光致发光光谱(PL)等测试方法对所得产物形貌和光学性能进行了研究,并对对两种纳米形态的形成机理进行了初步的探讨.结果表明:所得产物为六角纤锌矿型氧化锌纳米晶,分散性良好,形貌为枣核状,而这种枣核状的粒子是由众多短棒状粒子取向生长而形成的.升高温度,则得到了直径约100 nm,长约2 μm 的两头尖的纳米棒,棒的表面依附生长了针状颗粒.  相似文献   

17.
In this work, a novel system of ethylene glycol/water (EG/W) was employed to synthesize LiFePO4, in which dodecyl benzene sulphonic acid sodium (SDBS) was used as soft template to control particle morphology. The samples were characterized by X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and energy dispersive X-ray spectroscopy (EDX). The LiFePO4 sample obtained by the reported method displays interesting hierarchical nanostructure (i.e. nanodendrites), which was constructed by nanorods of 3–5 μm in length and ∼50 nm in diameter. The EG/W ratio, amount of SDBS added, hydrothermal temperature and duration played important roles in the assembly of the hierarchical nanostructures. A formation mechanism was proposed and experimentally verified. It is concluded that the nanodendrites were formed due to the end-to-end self-assembly of nanorods. Compared to previously reported methods, the reported approach shows obvious advantages of one-step synthesis, environmental friendliness and low cost, to name a few. The nanodendrites as a cathode material have a higher capacity, compared with the other samples.  相似文献   

18.
Pure Co3O4 microcrystals were prepared by a hydrothermal method from Co(NO3)2·6H2O and urea solution, and the effect of thermal treatment time on the growth of Co3O4 microcrystals was studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman and UV‐Vis absorption spectra. The results show that with the thermal treatment time increases from 2 h to 12 h, the shape of as‐prepared Co3O4 microcrystals changes from the hedgehog sphere‐like to the as‐cubic one that were stacked by lots of lamella, and finally cubes, and then longer time treatment will only lead to the size growth and agglomeration of particles. In conclusion, the cubic Co3O4 microcrystals of uniform size (∼6 μm) are synthesized via a 12‐h thermal treatment. Moreover, the synthesis mechanism has been studied.  相似文献   

19.
Monodisperse CeO2 spherical aggregates with diameters ranging from 200 to 300 nm have been successfully synthesized through a facile hydrothermal method. The structure and morphology of the samples were characterized by powder X‐ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and field‐emission scanning electron microscopy (FE‐SEM). The building blocks (primary nanocrystals) of the spherical aggregates could be effectively tuned by adding different amount of urea. Furthermore, N2 adsorption/desorption experiment displays a gradual increase of BET surface areas of spherical aggregates with increasing the amount of urea. Finally, the formation mechanism of CeO2 spherical aggregates was preliminarily discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

20.
Polycrystalline Bi2Te3 nanowires were prepared by a hydrothermal method that involved inducing the nucleation of Bi atoms reduced from BiCl3 on the surface of Te nanowires, which served as sacrificial templates. A Bi–Te alloy is formed by the interdiffusion of Bi and Te atoms at the boundary between the two metals. The Bi2Te3 nanowires synthesized in this study had a length of 3–5 μm, which is the same length as that of the Te nanowires, and a diameter of 300–500 nm, which is greater than that of the Te nanowires. The experimental results indicated that volume expansion of the Bi2Te3 nanowires was a result of the interdiffusion of Bi and Te atoms when Bi was alloyed on the surface of the Te nanowires. The morphologies of Bi2Te3 are strongly dependent on the reaction conditions such as the temperature and the type and concentration of the reducing agent. The morphologies, crystalline structure and physical properties of the product were analyzed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS).  相似文献   

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