Synthesis and characterization of single-crystalline PrCO3OH dodecahedral microrods and its thermal conversion to Pr6O11

Single-crystalline PrCO₃OH dodecahedral microrods with an orthorhombic structure have been successfully synthesized by the hydrothermal method used urea as the precipitator. Pr₆O₁₁ dodecahedral microrods have been obtained by thermal conversion of PrCO₃OH dodecahedral microrods at 600 °C in air for 6 h. The as-synthesized products were characterized by X-ray powder diffraction, field-emission scanning electron microscope, transmission electron microscopy, high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray photoelectron spectra, fourier transform infrared spectroscopy and thermogravimetry–differential thermal analysis. The effect of the reaction parameters on the morphology of the product has been investigated. The dodecahedral microrods with larger size and better crystallinity can be obtained under the higher reaction temperature. The possible formation mechanism of PrCO₃OH microrods was discussed.     

Dependence of photoluminescence properties on excitation power in ZnO and ZnCdO microrods

ZnO and ZnCdO microrods have been prepared through a chemical bath deposition method. The structure of microrods has been characterized using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Photoluminescence spectra were recorded for ZnO and ZnCdO microrods at different excitation powers. The intensity of UV emission is enhanced with increasing excitation power. The width of UV emission increases for spectra at higher excitation powers. In particular, the paper shows that the influence of excitation power on the shift of emission band for ZnCdO microrods is more remarkable than that of ZnO microrods with the increase of excitation power. The definite experimental evidence demonstrated that the temperature coefficient β of ZnCdO microrods is much larger than the temperature coefficient of ZnO microrods. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A template‐free route for controlled synthesis of dumbbell‐like Sb2S3 microcrystals

Large amounts of dumbbell‐like Sb₂S₃ microcrystals were synthesized via a simple solvothermal treatment method. Various techniques such as x‐ray diffraction (XRD), field‐emission scanning electron microscope (FESEM), high‐resolution transmission electron microscope (HRTEM), selected area electron diffraction (SAED), and photoluminescence spectrometry (PL) have been used to characterize the obtained products. The results showed that the products belong to the orthorhombic Sb₂S₃ phase, and the dumbbell‐like Sb₂S₃ microcrystals were composed by uniform microrods. Besides, the morphologies of Sb₂S₃ microcrystals could be changed from microshperes to dumbbell‐like microcrystals by only adjusting the reaction solvent. The solvent effects are discussed in detail. Furthermore, the PL properties of the obtained Sb₂S₃ microcrystals clearly show shape effects. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization and gas sensing properties of flowerlike In2O3 composed of microrods

Flowerlike structured In₂O₃ were successfully synthesized via a hydrothermal process and the subsequent calcinations. The obtained sample consists of microrods with an average diameter of 0.5‐1 μm and a length of 1‐3 μm. Structure and property of the sample were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The sensing properties towards trimethylamine (TMA) were examined at 200‐400 °C, which showed high sensitivity, better selectivity, and prompt response/recovery merits. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural and catalytic properties of Cu2S microrods grown on a three‐dimensional substrate

We present a facile solution‐phase method for the synthesis of Cu₂S microcrystals with rod‐like morphologies by the reaction of sulfur with three‐dimensional substrate copper foam in a mixed solvent of ethylene glycol and deionized water. The lengths of Cu₂S microrods are between 80 and 150 μm and the diameter is among 3 to 8 μm. Monodisperse Cu₂S microrods self‐assemble into echinus structure. The samples were characterized by X‐ray powder diffraction and scanning electron microscopy. Energy dispersive X‐ray spectroscopy was further used to testifiy the purity of Cu₂S. Catalysis performance proved that the obtained Cu₂S materials possess superior catalytic efficiency on methylene blue with the assistance of H₂O₂. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,conversion and comparison of the photocatalytic and electrochemical properties of ZnSe·N2H4 and ZnSe microrods

Novel ZnSe·N₂H₄ complex microrods with ∼2 μm in length and 100∼200 nm in diameter were successfully prepared by the solvothermal method at 110°C for 10 h, employing ZnAc₂·2H₂O and Se powders as the reactants, N₂H₄·H₂O as the reductant and medium. Experiments showed that the as‐obtained complex could be further converted into pure hexagonal ZnSe in an ethanol medium at 180 °C for 10 h, and the morphology hardly changed. The as‐prepared products were characterized by X‐ray powder diffraction (XRD), Energy dispersive spectrum (EDS), IR spectrum, Thermogravimetric (TG) analysis and Field emission scanning electron microscopy (SEM). Also, their photocatalytic degradation and electrochemical property were compared. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrothermal synthesis of nano‐crystalline BaMoO4 under mild conditions using simple additive

Large‐scale high‐quality BaMoO₄ nanocrystals have been synthesized in aqueous solutions under mild conditions with citrate as a simple additive. The crystals have bone‐like, spindle‐like and wheatear‐like morphologies assembled from nanoparticles, nanofibers and have been characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. The results showed that experimental parameters had great influences on the shape evolution of products. The adjustment of these parameters such as room temperature stirring time, reaction temperature and reaction time of hydrothermal reaction, can lead to obvious morphology changes of products, and the growth mechanism has been proposed. Room‐temperature photoluminescence indicated that the as‐prepared BaMoO₄ nanocrystals had a strong blue emission peak at 481.5 nm. This facile route could be employed to synthesize more promising nanomaterials with interesting self‐assembly structures. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Controllable synthesis of hierarchical strontium molybdate by sonochemical method

Large‐scale chrysanthemum‐like strontium molybdate (SrMoO₄) with hierarchical structure has been successfully synthesized via a facile and fast ultrasound irradiation approach at room temperature. By varying the experimental conditions, SrMoO₄ with different morphologies, such as spindles, peanuts, spheres, and rods, can be obtained. The products are characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected‐area electron diffraction (SAED). The influent parameters including concentration, pH value, and surfactants have been investigated. A possible growth mechanism is proposed and the shape evolution of the products is characterized. The as‐prepared chrysanthemum‐like SrMoO₄ particles are used as the precursor for electrorheological fluid and their electrorheological property is investigated.     

Polychloro‐alkanes used as templates in solvothermal synthesis of selenium microrods

Polychloro‐alkanes, including dichloromethane (CH₂Cl₂), chloroform (CHCl₃) and tetrachloromethane (CCl₄), were first introduced to synthesize trigonal selenium (t‐Se) microrods as a new kind of coordinating solvent, which played two important roles in the formation of Se nuclei and templated effect of Se microrods. The possible formation mechanism of t‐Se microrods was proposed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and tribological properties of Mo‐doped WSe2 Nanolamellars

The Mo‐doped WSe₂ nanolamellars have been successfully prepared via solid‐state thermal (750 °C) reaction between micro‐sized W, Mo with Se powders under inert atmosphere in a closed reactor and characterized by X‐ray diffractometer (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the morphologies of the as‐prepared products changed from microplates to nanolamellars to aggregations composed of nanoparticles with the doping of Mo powders. And the sizes of crystallites evidently reduced while the contents of dopant increased within a certain limit (1 wt.%–7 wt.%). The tribological properties of the as‐prepared products as additives in HVI750 base oil were investigated by UMT‐2 multispecimen tribotester. The friction coefficient of the base oil containing Mo‐doped WSe₂ nanolamellars was lower and more stable than that of WSe₂ nanolamellars. A combination of rolling friction, sliding friction, and stable tribofilm on the rubbing surface could further explain the good friction and wear properties of Mo‐WSe₂ nanoparticles as additives than that of WSe₂.     

辅助水热法制备不同形貌的柱状ZnO微晶

本文采用乙醇辅助水热法制备得到了柱状ZnO微晶.得到的微晶形貌多样,有单脚、三脚、四脚、五脚、六脚以及多脚状,并以"骨架+支架"模型进行解释.X射线衍射分析结果表明产物为纯的六方相纤锌矿结构,扫描电子显微镜(SEM)观察表明产物具有单晶属性.本文还研究了ZnO的室温光谱性能.     

Synthesis of strontium carbonate rods and hierarchical branches in the presence of two organic additives

In this paper, strontium carbonate (SrCO₃) crystals have been synthesized in the presence of two organic additives, including sodium citrate and hexamethylenetetramine (HMT). Scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, X‐ray powder diffractometry and selected area electron diffraction (SAED) were used to characterize the products. The results indicate that SrCO₃rods with the ratio of length to diameter about 20 are obtained in the aqueous solution containing sodium citrate. While polycrystalline SrCO₃ hierarchical branches with about 10 μm length are produced by using HMT.The possible formation mechanism of the SrCO₃crystals obtained in above two systems is discussed, which can be interpreted by particle‐aggregation based non‐classical crystallization laws. Sodium citrate and HMT may direct the formation of SrCO₃ rod‐like or branch‐like structures by adsorbing onto certain facets of SrCO₃ crystals. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Capsule‐like α‐Fe2O3 nanoparticles: Synthesis,characterization, and growth mechanism

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.     

Synthesis and characterization of strontium chloroborate whiskers

Single crystalline strontium chloroborate (Sr₂B₅O₉Cl) whiskers with uniform diameter have been synthesized by a facile route based on the calcination of precursor. The precursor was prepared by the sedimentation reaction between SrCl₂ and Na₂B₄O₇ aqueous solution. The products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectrum (FT‐IR). An optimal synthesis temperature for preparing Sr₂B₅O₉Cl whiskers was obtained, and the possible formation process was also presented.     

Kinetically controlled synthesis of hollow Cu2O nanocubes under solvothermal condition

Hollow Cu₂O nanocubes have been fabricated under solvothermal condition using N,N ‐dimethylformamide (DMF) as solvent at 120 °C for 12 h. The products were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray powder diffraction (XRD) and high‐resolution transmission electron microscopy (HRTEM). Series of experiment confirmed that the amount of water, the reaction time and temperature played important roles in the morphology evolution of hollow Cu₂O nanocubes. DMF is a relatively weak alkali solvent and could release a certain amount of OH^– under the given conditions. As the release speed of OH^– from DMF became substantially slow, the nucleation and growth of Cu₂O nanocubes turned into kinetically controlled process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Additive induced morphology changes of nano‐crystalline SrWO4

Large‐scale high‐quality SrWO₄ nanocrystals have been synthesized in aqueous solutions under mild hydrothermal conditions with citrate as a simple additive. The crystals undergo an interesting 0‐D to 1‐D and to 0‐D morphology changes and have been characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The results showed that the experimental parameters had great influences on the shape evolution of products. The adjustment of these parameters such as the addition of the citrate and hydrothermal reaction conditions, can lead to obvious morphology changes of products, and the growth mechanism has been proposed. Room‐temperature photoluminescence indicated that the as‐prepared SrWO₄ nanocrystals had strong emission peaks at about 434 and 506 nm, respectively. This facile route could be employed to synthesize more promising nanomaterials with interesting self‐assembly structures. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

α‐Fe2O3 nanospindles loaded with ZnO nanocrystals: Synthesis and improved gas sensing performance

ZnO/α‐Fe₂O₃ nanocomposites were fabricated through a two‐step hydrothermal method. The morphology and composition of the as‐synthesized products were characterized by X‐ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The gas sensing properties of the fabricated products were investigated towards ethanol, acetone, propanol, isopropanol, formaldehyde, chloroform and so on. The results demonstrated that the ZnO/α‐Fe₂O₃ nanocomposites exhibited excellent sensing properties and showed remarkably higher sensing responses and much lower optimum operating temperature compared to individual ZnO and α‐Fe₂O₃. In addition, the ZnO/α‐Fe₂O₃ nanocomposites have some selectivity for ethanol, propanol and isopropanol. The possible gas sensing mechanism was also proposed. Our studies demonstrate that our fabricated materials could be widely used in the future.     

Catanionic surfactants assisted synthesis of dilead pentaoxochromate nanorods

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)     

PMA‐b‐PAA‐controlled synthesis of one‐dimensional CaCO3 superstructures

Crystallization of calcium carbonate (CaCO₃) crystals by a gas‐liquid diffusion method has been carried out in aqueous solution using a double‐hydrophilic block copolymer (DHBC) poly(maleic anhydride)‐b‐poly(acrylic acid) (PMA‐b‐PAA). The as‐prepared products were characterized with X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), high‐resolution transmission electron microscopy (HRTEM) and infrared spectroscopic analysis (FT‐IR). Uniform one‐dimensional calcite micro/nanostructures with different morphologies are fabricated through an assembled process. The influence of PMA‐b‐PAA copolymer concentration on the morphology of calcite nano/microwires is investigated, which plays an important role in the morphological control of building blocks composed of one‐dimensional calcite crystals. The possible formation mechanism of one‐dimensional CaCO₃ crystals was discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Facile morphology‐controlled hydrothermal synthesis of flower‐like self‐organized ZnO architectures

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)