Antimony-doped tin oxide (ATO) nanoparticles with controlled doping level were prepared by a nonaqueous solution route, using alcohol as the solvent, citric acid as an agent, tin (IV) tetrachloride as tin source and a...
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ISBN:
(纸本)9783037856079;3037856076
Antimony-doped tin oxide (ATO) nanoparticles with controlled doping level were prepared by a nonaqueous solution route, using alcohol as the solvent, citric acid as an agent, tin (IV) tetrachloride as tin source and antimony (III) chlorideas as antimony sources. As-synthesized samples were characterized by Thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), transmission electron micrographs (TEM), N2 adsorption-desorption isotherms, and X-ray photoelectron spectroscopy (XPS). The results showed that the content of citric acid was the most important processing parameter which was largely governing the reaction course and the complete incorporation of Sb. When the citric acid to metal mol ratio was 2, the particles were the highly crystallized ATO nanoparticles of about 20nm and the Sb atoms were indeed incorporated into the SnO2 crystal structure (cassiterite SnO2 ).
SiC/Cu composites exhibit low density, low coefficient of thermal expansion and excellent mechanical properties. In this study, Zn of 2 wt. % was added as the sintering activator, and the high volume faction (60%) SiC...
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ISBN:
(纸本)9783037856079;3037856076
SiC/Cu composites exhibit low density, low coefficient of thermal expansion and excellent mechanical properties. In this study, Zn of 2 wt. % was added as the sintering activator, and the high volume faction (60%) SiC/Cu composites was fabricated by hot pressing sintering technology. The phase composition and morphology of as-prepare samples were characterized by X-ray diffraction (XRD) system and scanning electron microscopy (SEM) equipped with an energy-dispersive spectroscopy (EDS) system. The as-prepared SiC/Cu composites were dense and uniform as well as void free. The results show that SiC/Cu composites can reach excellent mechanical properties of SiC/Cu composites. With the increase of sintering temperature, Vickers hardness and the bending strength of the samples increased obviously and the as-prepared SiC/Cu composites achieved a maximum Vickers hardness and bending strength respectively of 195MPa and 140MPa.
Bismuth strontium titanate ceramics are rarely used for energy storage. In this paper, the energy storage characteristics of bismuth strontium titanate ceramics (1-(x/3))SrTiO 3 -(x/3)(Bi 2 O 3 ·3TiO 2 ) were sys...
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Bismuth strontium titanate ceramics are rarely used for energy storage. In this paper, the energy storage characteristics of bismuth strontium titanate ceramics (1-(x/3))SrTiO 3 -(x/3)(Bi 2 O 3 ·3TiO 2 ) were systematically researched. The traditional solid phase sintering method was employed for preparing bismuth strontium titanate ceramics. The frequency dependence of dielectric constant, the frequency dependence of the dielectric loss, and the DC electric field dependence of dielectric constant were measured. The energy storage density was obtained by integrating the area within the polarization axis and the discharge curve in the polarization-electric field (P-E) curve. Experimental results show that, when x=0.15, (1-(x/3))SrTiO 3 -(x/3)(Bi 2 O 3 ·3TiO 2 ) ceramic has high dielectric constant, fine frequency stability, high resistivity, low dielectric loss and weak DC electric field dependence of dielectric constant. And its energy storage density could achieve 1.63 J/cm 3 at 217.6 kV/cm electric field. Thus, it may possess the potential being used as a kind of energy storage dielectric material.
Laminated ZrB2-SiC ceramics with porous ZrB2 interlayers were successfully prepared by Spark plasma Sintering (SPS)/tape casting, laminating and Reactive Spark Plasma Sintering (RSPS). ZrB2-SiC plates were sintered by...
Laminated ZrB2-SiC ceramics with porous ZrB2 interlayers were successfully prepared by Spark plasma Sintering (SPS)/tape casting, laminating and Reactive Spark Plasma Sintering (RSPS). ZrB2-SiC plates were sintered by SPS. And ZrO2-B4C sheets were prepared by tape casting, which will undergo reducing reaction that produces porous ZrB2 interlayers during SSPS processing. The ZrB2-SiC plates and ZrO2-B4C sheets were laminated alternately and reactive sintered to laminated ceramics with porous ZrB2 interlayers. The porosity and thickness of the porous layers were controlled by the tape casting processing and sintering pressure. The microstructure of the laminated ZrB2-SiC ceramics was analysed and discussed in details.
The ZrB2/SiC/Zr2Al4C5 multi-phase ceramics were fabricated by spark plasma sintering (SPS) at 1800 °C for 3 min under 20 MPa in an vacuum. Oxidation behavior of multi-phase ceramics were investigated using thermo...
The ZrB2/SiC/Zr2Al4C5 multi-phase ceramics were fabricated by spark plasma sintering (SPS) at 1800 °C for 3 min under 20 MPa in an vacuum. Oxidation behavior of multi-phase ceramics were investigated using thermo gravimetric analysis (TGA) from 20 °C to 1500 °C and muffle furnace in stagnant air at 1200 °C. Samples were analyzed after oxidation by X-ray diffraction (XRD), scanning electron microscopy (SEM) along with energy dispersive spectroscopy (EDS) to determine the reaction products and to observe the microstructure. The results showed that the aluminium borate and mullite crystallize on the surface in the samples oxidized. The effect of Zr2Al4C5 content on the oxidation resistance of the ZrB2 ceramics were discussed respectively, and oxidation mechanism was also analysised.
Life is a typical chiral system,and chiral phenomena are ubiquitous in nature from macroscopic to molecular levels.1 For example,small natural biomolecules are mostly chiral molecules which show distinct chiral prefer...
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Life is a typical chiral system,and chiral phenomena are ubiquitous in nature from macroscopic to molecular levels.1 For example,small natural biomolecules are mostly chiral molecules which show distinct chiral preference,e.g.L-amino acids,D-sugars, L-phospholipids,etc..They integrate together via multiple chemical bonding or weak molecular interactions to form biomacromolecules with special steric confomiations and functions,which further assemble to form organelles,cells,tissues,and organs.
Multilayered TiO2/ATO thin films were prepared by the spin-coating method to evaluate the electronic interactions and the effect of the experimental conditions on optical transparency, electric resistivity and carrier...
Multilayered TiO2/ATO thin films were prepared by the spin-coating method to evaluate the electronic interactions and the effect of the experimental conditions on optical transparency, electric resistivity and carrier density. ATO chemical composition, number of layers and annealing temperature were modified to study their effect on the global properties of the TiO2/ATO system. TiO2/ATO films exhibited an optical transparency as high as 81 % in the visible wavelength and a strong absorption within the UV spectra. Electric resistivity as low as 3.4 × 10−1 Ωcm was measured for TiO2/ATO films. Optical properties were influenced mainly by the presence of upper TiO2 layer and ATO film thickness. The effect of ATO film thickness, composition and annealing temperature on TiO2/ATO transparency and resistivity are discussed.
The isothermal oxidation behaviors at 800-1000 ℃ for 20h in air of bulk Ti2 AlN and Ti2 AlN/TiN were investigated by TG,XRD and SEM coupled with *** oxidation behaviors generally follow the parabolic *** activation e...
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The isothermal oxidation behaviors at 800-1000 ℃ for 20h in air of bulk Ti2 AlN and Ti2 AlN/TiN were investigated by TG,XRD and SEM coupled with *** oxidation behaviors generally follow the parabolic *** activation energies of Ti2 AlN and Ti2 AlN/TiN composite are 614.93 KJ mol-1 and 541.35 KJ mol-1 *** antioxidation property of Ti2 AlN/TiN composite is better than Ti2 *** process of single-phase Ti2 AlN is composed by the outward diffusion of Al3+ and Ti4+,and inward diffusion of *** process of Ti2 AlN/TiN composite consists of two parts:firstly,the oxidation of TiN,the oxidation temperature is 500 ℃;the second step is the oxidation of Ti2 AlN,carried out mainly in the 800-1000 ℃.
In our present work, the effect of the Zn-vacancy concentration on the lattice thermal conductivity of β-Zn4Sb3 at room temperature is studied by using the nonequilibrium molecular dynamics approach. Along both the x...
In our present work, the effect of the Zn-vacancy concentration on the lattice thermal conductivity of β-Zn4Sb3 at room temperature is studied by using the nonequilibrium molecular dynamics approach. Along both the x- and z- axes, the heat flux and the temperature gradient exponentially decay and increase respectively. The lattice thermal conductivity of the single crystal bulk β-Zn4Sb3 rapidly decreases when there exists Zn atom vacancy, and then the lattice thermal conductivity slowly falls further with the growing Zn atom vacancy proportion, which suggests that the Zn atom vacancy (nv) to the lattice thermal conductivity (kvac) leads to a scaling law of kv ∼ nv−α This phenomenon is attributed to the fact that the existence of vacancy scattering can significantly decrease the mean free path. When the vacancy proportion of Zn atom reaches 10%, that is the vacancy model of β-Zn4Sb3, the lattice thermal conductivity of β-Zn4Sb3 is 1.32 W/mk and 1.62 W/mk along the x- and z- axes respectively, which drops by ∼ 90% than that of its full occupancy model.
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