This article introduces a process for the growth of one-dimensional oxide nanomaterials that combines rheological phase reaction and hydrothermal self-assembling process. Fundamentals and practical approaches of hydro...
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This article introduces a process for the growth of one-dimensional oxide nanomaterials that combines rheological phase reaction and hydrothermal self-assembling process. Fundamentals and practical approaches of hydrothermal self-assembling process and rheological phase reaction are briefly described. Particular attention is devoted to the rheological self-assembling for the growth of low dimensional oxide nanomaterials. Many examples are shown that the rheological self-assembling is an effective method to prepare one-dimensional nanomaterials, organic-inorganic hybrids and 1-D nanomaterial array for optical-electronic and electrochemical devices and catalysis. Morphologies, microstructures, properties, and application of one-dimensional oxide nanomaterials are reviewed.
Novel mesoporous ZnO-SiO2 (MZS) composites with rod-like morphology were synthesized from coprecipitation method, which was the first time to apply this method in the successful synthesis of ordered mesoporous composi...
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Novel mesoporous ZnO-SiO2 (MZS) composites with rod-like morphology were synthesized from coprecipitation method, which was the first time to apply this method in the successful synthesis of ordered mesoporous composites to our knowledge. This direct-synthesis method was more simple, convenient and efficient, compared with the post-synthesis ones. Structural characterization and spectroscopic study were discussed.
After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were di...
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After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were distinguished. The results showed that the bigger particles or less thickness of material could benefit to the anti-voltage strength and ultimately enhanced the energy storage density of composites. Moreover, the distribution of particle dimension also influenced the strengths of materials. Composite with homogeneous particles performed higher strength than that of composites with inhomogeneous particles.
In the study Li4/3Ti5/3O4 thin films were deposited on Pt substrates by sol-gel method using a spin coator. The coated films are dried at 310-360 °C, and then annealed at 500-800 °C for 30min. The prepared f...
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In the study Li4/3Ti5/3O4 thin films were deposited on Pt substrates by sol-gel method using a spin coator. The coated films are dried at 310-360 °C, and then annealed at 500-800 °C for 30min. The prepared films were characterized by X-ray diffraction, atomic force microscope and scanning electron microscope. The results indicated that the prepared film belonged to a spinel structure and had a uniform morphology. Electrochemical properties of the prepared electrode films were evaluated by using a discharge and charge test. From these results, it can be showed that the thin film electrode annealed at 700 °C exhibited good crystallinity, smooth surface morphology, high capacity, and good rechargeability. Therefore, This film was therefore suitable for use as an anode for thin-film microbatteries.
Sr-filled skutterudite compounds SryCo4Sb 12 (y=0-0.20) were synthesized by melting method. XRD and EPMA results revealed that the obtained samples are single skutterudite phase with homogeneous chemical composition. ...
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Sr-filled skutterudite compounds SryCo4Sb 12 (y=0-0.20) were synthesized by melting method. XRD and EPMA results revealed that the obtained samples are single skutterudite phase with homogeneous chemical composition. The lattice parameters increase linearly with increasing Sr content in the range of y=0-0.20. The thermal conductivity, electrical conductivity and Seebeck coefficient were measured in the temperature range of 300-850K. The measurement of Hall effect was performed by Van de Pauw method at room temperature. The obtained Sr-filled skutterudite exhibits n-type conduction. The absolute value of the Seebeck coefficient of Sr yCo4Sb12 decreases with the increase of Sr content. The electrical conductivity increases with the increase of Sr content. The lattice thermal conductivity of SryCo4Sb12 is significantly depressed as compared with unfilled CoSb3. The maximum dimensionless thermoelectric figure of merit is 0.7 for Sr 0.20Co4Sb12 at 850K. Further optimization of chemical composition would improve the thermoelectric performance.
A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The ex...
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A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The experiment procedure includes two stages, heating the specimen from the initial temperature 30°C for 40s, and then cooling for 20s. The heat transfer and the associated thermal stresses produced during the thermal shock procedure are simulated by finite element method. Experimental results indicated that the specimen of gradient coating behaves better in thermal shock experiments, which agree with the results of simulation.
The Yb-filled Yb x Co 4 Sb 12 (times=0.2-0.5) bulk materials with special nanostructure were prepared by combining melt spinning method with spark plasma sintering (SPS). The microstructure and thermal transport prop...
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The Yb-filled Yb x Co 4 Sb 12 (times=0.2-0.5) bulk materials with special nanostructure were prepared by combining melt spinning method with spark plasma sintering (SPS). The microstructure and thermal transport property of Yb x Co 4 Sb 12 were investigated. The microstructure observations were performed by using high-resolution transmission electron microscopy and field emitted scanning electron microscopy (HRTEM and FESEM). The results show that ribbon-shaped samples after melt spinning are composed of nanocrystals and amorphous-like phases, and possess preferable crystal granularity and evengranular distribution with roller linear speed of 30 m/s and nozzle pressure of 0.02 MPa; the bulk materials after SPS are composed of minicrystals with 200 nm average diameter which is formed by nanocrystals with 5-20 nm diameter. This special microstructure increases grain boundary scattering notably, and has great effect on phonon behavior. As a result, the thermal conductivity of the material is decreased remarkably. Compared with the sample prepared by melting-quench-diffusion annealing method with the same filling fraction (times=0.5), thermal conductivity of the sample prepared by melt spinning method decreased 50% from 4.0 Wm -1 K -1 to 2.0 Wm -1 K -1 at 600 K, and the sample still possesses relatively high power factor.
P-type Bi 0.5 Sb 1.5 Te 3 bulk material with fine nanostructure has been prepared by combining melt spinning technique with spark plasma sintering (SPS), and the effects of microstructure on the thermoelectric transp...
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P-type Bi 0.5 Sb 1.5 Te 3 bulk material with fine nanostructure has been prepared by combining melt spinning technique with spark plasma sintering (SPS), and the effects of microstructure on the thermoelectric transport properties are investigated. Bi 0.5 Sb 1.5 Te 3 ribbons with fine nanostructure are obtained during the melt spinning process and the grain sizes of Bi 0.5 Sb 1.5 Te 3 are about 5-15 nm observed by High-resolution transmission electron microscopy. Such structure has great influence on thermoelectric transport properties of Bi 0.5 Sb 1.5 Te 3 compound. Compared with zone melting and directing SPS samples, the lattice thermal conductivity of the sample processed by melt spinning decreases significantly due to the intensive phonon scattering induced by the fine nanostructure. The greatest thermoelectric figure of merit (ZT) of 1.20 is obtained at 300K for the sample which is prepared by melt spinning with roller linear speed of 10 m/s.
P-type Ba 8 Ga 16 Cd x Ge 30-x (x=0.95, 1.00, 1.05, 1.10) type-I clathrates with different Cd contents were synthesized by combining melt method with spark plasma sintering (SPS). The effects of Cd content on electri...
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P-type Ba 8 Ga 16 Cd x Ge 30-x (x=0.95, 1.00, 1.05, 1.10) type-I clathrates with different Cd contents were synthesized by combining melt method with spark plasma sintering (SPS). The effects of Cd content on electrical transport properties have been investigated. The results show that all samples exhibit p-type conduction. The Seebeck coefficient alpha and room temperature carrier mobility mu H decrease with the increasing Cd content. The electrical conductivity sigma and the room temperature carrier concentration N p increase with the increase of Cd content. In the low temperature range (T<150 K), the carrier scattering mechanism is mainly ionized impurity mechanism, and gradually changes to an acoustical mechanism with the rising temperature. The maximum power factor value of 0.35times10 -3 Wm -1 K -2 is obtained at 550 K for Ba 8 Ga 16 Cd 1.00 Ge 29.00 .
A kind of gradient thermal and environmental barrier coating applied in internal combustion engine is brought forward to improve its reliability, emission and efficiency. The multi-layer plate and cylinder models are ...
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A kind of gradient thermal and environmental barrier coating applied in internal combustion engine is brought forward to improve its reliability, emission and efficiency. The multi-layer plate and cylinder models are established for the simulations of heat transfer and thermal stress in the coatings. Both the theoretical and the numerical analysis with multi-layer cylinder model with coating inside are carried out and compared. The results show good agreement.
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