Papers by Keyword: Hydrothermal Method

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Authors: Xiao Ming Fu, Zhao Wen Liu, Liang Yi Zhou, Chen Chen Xie
Abstract: β-Ni(OH)2 flower-like spheres and nanoflakes were synthesized with strong ammonia water as precipitator and nickel nitrate as nickel source by the hydrothermal method. The phase structure and morphologies were analyzed using XRD and SEM. The results showed that under the same conditions of the pH value and the reaction time, the low temperature was propitious to synthesize β-Ni(OH)2 flower-like spheres. High temperature was in favor of the synthesis of β-Ni(OH)2 nanoflakes. Namely, β-Ni(OH)2 flower-like spheres were obtained at 180 °C for 48.0 h with pH=9.0. β-Ni(OH)2 nanoflakes were prepared at 240 °C for 48.0 h with pH=9.0. The formation mechanism was explored through observing influence of the conditions of the hydrothermal method on the morphologies of the samples.
1430
Authors: Xiao Ming Lou, Jia Li Huang, Tan Ping Li, Han Xiang Hu, You Xiang Zhang, Ke Li Zhang
Abstract: In this paper, manganite (γ-MnOOH) nanowires have been synthesized, using KMnO4 and CTAB as raw materials, by a hydrothermal method at 180°C for 12h. The samples were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM),and thermogravimetric analysis (TG) for the information of crystal form, size, d-spacings, morphology and the weight-loss course. The results showed the manganite nanowires diameter range from 15 nm to 150 nm,length range from 5μm to 20 μm. Moreover, the properties of manganite (γ-MnOOH) nanowires as anode materials for Li-ion batteries had been studied. The first-discharge capacity is 1660 mAh g-1 and corresponds to a consumption of about 5.5 moles of Li per mole of MnOOH, which made this material maybe one of the candidates for the negative materials.
677
Authors: Fang Chao Xu, Kazuhiro Kusukawa
Abstract: Lead-free piezoelectric (Bi1/2Na1/2)TiO3 (BNT) films were deposited on 0.2 mm thick pure titanium (Ti) substrates by a hydrothermal method. Scratch tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition with a view of investigating the effects of substrate surface pretreatments on the adhesion of BNT film. In the scratch test, the behaviour of BNT film exfoliation was investigated by SEM observation. The scratch test results revealed that the chemical polish pretreatment effectively improved the adhesion of BNT films.
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Authors: Fang Chao Xu, Kazuhiro Kusukawa
Abstract: Lead-free piezoelectric (Bi1/2Na1/2)TiO3 (BNT) films were deposited on 1 mm thick pure titanium(Ti) substrates by a hydrothermal method. Tensile tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition. In the tensile test, the behavior of BNT film exfoliation was investigated by the replica method. The critical Ti substrate strain inducing BNT film exfoliation was determined by the aid of finite element analysis (FEM). In this study, the results revealed that BNT film exfoliations were caused by the strain of Ti substrate, and the mechanical polish pretreatment improved the adhesion of BNT film to Ti substrate.
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Authors: Guan Qin Chen, Zhang Lian Hong
Abstract: Low frequency ultrasonic treatment was applied to desorb surface organics from the surface of nanosized TiO2 photocatalyst, which was prepared by hydrothermal method using a mixture of different amounts of Ti(OBu)4, ethanol, acetone and pyridine raw materials. The UV-Vis, TG-DTA and GC-MS analysis were used to investigate the surface organics. It was found that the absorption intensity around 250nm in UV-Vis spectra of the upper transparent solution, which represents the amount of organics desorbed from the TiO2 surface, increased with increasing treatment time. Along with the TG-DTA and GC-MS analysis, the kinds and amounts of partial surface organics were roughly clarified, and these organics may correspond with the photocatalytic degradation rate for methyl orange (MO) solution under visible light irradiation (≥450nm).
2304
Authors: Xiao Ming Fu, Zhao Wen Liu
Abstract: Anatase nano titanium oxide was synthesized with Ti(SO4)2 as titanium source and stronger ammonia water as precipitant using the hydrothermal method. The samples were characterized by XRD, SEM, TEM and UV-VIS. The results showed that the influence of the increase of the reaction time on as-prepared anatase nano titanium oxide was not obvious when stronger ammonia water was not added to Ti(SO4)2 solution. Anatase nano titanium oxide became small markedly under the same conditions when stronger ammonia water was added to Ti(SO4)2 solution. Anatase nano titanium oxide of about 20 nm in the diameter was obtained for 48 h with pH=9 at 240 °C by the hydrothermal method. That the size of Anatase nano titanium oxide particles became small was propitious to the blue shift of their absorption peak.
1198
Authors: Gabriela Borin Barin, Thalita Santos Bispo, Iara de Fátima Giminenez, Ledjane Silva Barreto
Abstract: Brazil has a large potential for energy generation and development of new materials from renewable resources through eco-friendly routes, which presents an alternative for construction of an eco-technological platform, where the entire lifecycle of the material or industrial product be sustainable. The proposal of the present work was synthesize carbon nanostructures from coconut coir dust and via template synthesis mediated by layered clays through hydrothermal process. The obtained materials were characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope (SEM). Carbon phase formation was indicated by infrared results with bands at 1444 cm-1 and 1512 cm-1 assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. SEM results showed overlapping sheets and plates formation. High Resolution Transmission Electron Microscopy measures are in progress.
1355
Authors: Fang Chao Xu, Kazuhiro Kusukawa
Abstract: Thin films of lead-free piezoelectric ceramics (Bi1/2Na1/2)TiO3 (abbreviated as BNT) were prepared on pure titanium substrates by a hydrothermal method. Several properties of BNT films synthesized in various Bi3+ and Ti4+ concentrations of starting materials were investigated using SEM, EDX, XRD and other instruments. Moreover, the effects of ion concentrations of starting materials on permittivity and piezoelectric effect of BNT films were discussed. The Bi2O3 crystals were more deposited on the surface of films with the increase of the concentration of Bi3+. The relationship between the deflection and applied electric field was measured on unimorph cantilever type actuators made from three samples which had different XRD patterns. The results showed that the piezoelectric effect of BNT films was dependent on the crystallization level of BNT.
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Authors: Yan Wang, Jin Hui Lin, Hui Li, Miao Deng, Shan Hua Chen
Abstract: Bismuth sodium titanate (Na1/2Bi1/2)TiO3 powders were prepared by the hydrothermal route with starting chemicals containing Ti (OC4H9)4, Bi (NO3)35H2O as Bi and Ti sources at 180°C for 48 h in a PTFE-lined autoclave. XRD result confirms the formation of a pure pervoskite structure for the synthesized powders. SEM observation shows that the powders consist of spherical particles in the range of 0.2~1.0 μm, exhibiting a mean particle size of 0.5 μm. Compared with (Na1/2Bi1/2)TiO3 ceramics made by the conventional solid state reaction method, the specimen made by the hydrothermal synthesis method has superior piezoelectric properties with its piezoelectric constant d33 attaining a relatively high value of 78 pC/N.
135
Authors: Pei Song Tang, Hai Feng Chen, Feng Cao, Guo Xiang Pan, Min Hong Xu
Abstract: The Nano-Bi2MoO6 was prepared using Bi(NO3)3•5H2O and Na2MoO4•2H2O as starting materials by a hydrothermal process. The prepared Bi2MoO6 product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). It was found that the prepared nano-Bi2MoO6 show narrow band gap of 2.88 eV. Consequently, the prepared nano-Bi2MoO6 show high visible-light photocatalytic activity for decomposition of Rhodamine B in comparison with the commercial Degussa P25, which was ascribed to the visible-light absorption.
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