ZnO sub-millimeter crystals were synthesized by microwave heating from ZnO powders without any catalyst or transport agent. Zinc oxide raw materials were evaporated from the high-temperature zone in an enclosure and c...
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ZnO sub-millimeter crystals were synthesized by microwave heating from ZnO powders without any catalyst or transport agent. Zinc oxide raw materials were evaporated from the high-temperature zone in an enclosure and crystals were grown on the self-source substrate. The thermodynamics analysis method was used to estimate the partial pressure of gases in the chamber, which shows that the pressure of ZnO could be neglected entirely in the range of experiment temperature. The kinetics analysis was employed to estimate the growth rate in different conditions, which shows a remarkable temperature gradient and a high system temperature would enhance the growth rate. Optics photos reveal that these products are hexagon crystals with 0.2-0.3 mm in diameter and 0.5-1 mm in length. A vapor-solid mechanism is proposed to explain the growth process of ZnO crystals. The temperature distribution in microwave oven is mainly determined by properties of electric field and it is different from that of a conventional method.
Fe doped In2O3 samples （In1-xFex）2O3 （x=0, 0.05, 0.1, 0.2 and 0.3） on glass substrate were prepared by sol-gel method. The XRD results demonstrate that the solubility of Fe ions in In2O3 matrix is around 20%, abov...
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Fe doped In2O3 samples （In1-xFex）2O3 （x=0, 0.05, 0.1, 0.2 and 0.3） on glass substrate were prepared by sol-gel method. The XRD results demonstrate that the solubility of Fe ions in In2O3 matrix is around 20%, above which impurity phase can be observed. The transmittance of the samples with x=0, 0.05, 0.1 and 0.2 are above 80% in the visible region while the transimittance of the glass is 90%. The transmittance curves slightly red-shifts as x increasing. All of the samples except x=0 are ferromagnetic at room temperature. The highest saturation magnetization moment is reached in the sample x=0.2 with 330 emu/cm3, and the coercive force is 169 Oe which is also the largest in our samples. The results indicate that the addition of Fe ions could tune the structure, the ferromagnetism and optical property in the In2O3 matrix.
About 300 μm thickness uniform thermal barrier coatings （TBCs） were deposited on the 1Cr18Ni9Ti samples by solution precursor plasma spray （SPPS）.The analysis methods,such as TEM,SEM,and XRD were used to characte...
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About 300 μm thickness uniform thermal barrier coatings （TBCs） were deposited on the 1Cr18Ni9Ti samples by solution precursor plasma spray （SPPS）.The analysis methods,such as TEM,SEM,and XRD were used to characterize the coatings in the aspects of microstructure and phase *** samples were quenched from 1121 ℃ to room temperature by forced-air to measure the thermal cycling *** density were measured by means of water *** experimental results show that grain size of the SPPS TBCs is about 30 nm with desired tetragonal phase ZrO2,and the SPPS TBCs（with 16% porosity） consist of arcuate pores,gelatin and melted *** hardness of the coatings is HR45Y38.5 and bond strength between coatings and substrates is 24.2 *** thermal shock test show the coatings have a average life of 500 cycles which is about 2.5 times than that of conventional air plasma spray （APS） TBCs.
The gas diffusion layer (GDL) of the proton exchange membrane fuel cell (PEMFC) plays a prominent effect on the water balance inside the fuel cell. A two-dimensional, steady-state, two-phase model for a PEMFC is devel...
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A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly（styrene-co-acrylic acid） [P（St-co-AA）] particles....
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A simple method was developed to prepare the uniform hematite hollow submicro-spheres with controllable structure and different diameter based on monodisperse poly（styrene-co-acrylic acid） [P（St-co-AA）] particles. The structure and formation mechanism of the hollow spheres were investigated in detail. The control mechanism of shell thickness was also discussed. The results indicated that the shell thickness and coarseness of the synthesized core-shell hematite hollow spheres could be tuned simply by the surface carboxyl content of the P（St-co-AA） particles. This method provided a new approach for the structure control in the preparation of hollow spheres. A Brunauer-Emmett-Teller （BET） test shows that the prepared hollow spheres have large surface areas which were decreased along with the increase of the diameter. The magnetic properties of the as-obtained hematite hollow spheres were investigated. The result showed that the coercivity and saturated magnetization were increased along with the increase of the shell thickness, and the remanent magnetization was increased along with the decrease of the diameter.
Catalytic effects of NiCl,TiC and TiN on the dehydrogenation/rehydrogenation characteristics of LiAlH were investigated by pressure -content-temperature(PCT),X-ray diffraction(XRD),differential scanning calorimatory(D...
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Catalytic effects of NiCl,TiC and TiN on the dehydrogenation/rehydrogenation characteristics of LiAlH were investigated by pressure -content-temperature(PCT),X-ray diffraction(XRD),differential scanning calorimatory(DSC),and field emission scanning electron microscopy(FESEM).The doped samples exhibit dehydrogenation at much lower *** with NiCl,TiC and TiN induce a decrease in the decomposition of first step by about 50-65℃compared to that of as received ***,amount of hydrogen release is significantly higher for TiC additions than that of samples doped with TiN and *** desorption results at 125℃reveal that dehydrating rate of doped alanate is much faster than that of pure ***,TiN and NiCl dopants show the reabsorption of about 1.9 wt.%, 1.3 wt.%,and 1.1 wt.%,*** and FESEM analyses suggest that both TiC and TiN are stable during the ball milling as well as the dehydrogenation *** the contrary,NiCl reacts and causes the partial decomposition of Li alanate during the ball milling process.
Cr(N,O) thin films were deposited by radio frequency reactive unbalanced magnetron sputtering on Si(100) or glassy carbon substrates. In this paper, the influence of oxygen content on hardness of Cr(N,O) thin films wa...
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Cr(N,O) thin films were deposited by radio frequency reactive unbalanced magnetron sputtering on Si(100) or glassy carbon substrates. In this paper, the influence of oxygen content on hardness of Cr(N,O) thin films was investigated. The compositional analysis was carried out by Rutherford backscattering spectroscopy. It was found that these thin films contained up to 44at.% of oxygen. Phases in the samples were determined by X-ray diffraction. Cr(N,O) thin films show only peaks based on CrN. The microstructure was observed by utilizing a transmission electron microscope. At
Polycrystalline samples of Sr5PrTi3Ta7O30 （SPTT） and Sr5EuTi3Ta7O30 （SETT） compounds were prepared by high-temperature solid-state reaction method and their formation, structure and dielectric properties were stud...
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Polycrystalline samples of Sr5PrTi3Ta7O30 （SPTT） and Sr5EuTi3Ta7O30 （SETT） compounds were prepared by high-temperature solid-state reaction method and their formation, structure and dielectric properties were studied. They are found to be ferroelectric phase of filled tetragonal tungsten bronze （TB） structure at room temperature and undergoes diffuse type of ferroelectric-paraelectric phase transition around 34 ℃ and 31 ℃, respectively. At 1 MHz SPTT exhibits high dielectric constants of 177 and low dielectric losses of 3.5×10^-4 and SETT has high dielectric constants of 125 and low dielectric losses of 2.4×10^-3.
Highly sensitive and selective nanosensor for labile iron pool (LIP) determination, has been designed and prepared by immobilization of Fluoresceine–Desferrioxamine (Fl–DFO), a bifunctional fluoro-siderophore probe ...
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Highly sensitive and selective nanosensor for labile iron pool (LIP) determination, has been designed and prepared by immobilization of Fluoresceine–Desferrioxamine (Fl–DFO), a bifunctional fluoro-siderophore probe molecule with great affinity for iron ions (pK f = 30.7), into highly ordered mesoporous silica structure. Different immobilization methods of Fl–DFO molecules, such as their encapsulation in surfactant micelles used as templating agents for the synthesis of mesoporous silica, direct impregnation into the mesochannels of as-synthesized mesoporous silica and their surface anchoring by covalent binding with propylamine groups implanted by post-synthesis on the internal surface of mesochannels, have been explored. Each nanohybrid has been fully characterized by small angle XRD, TEM, SEM, solid state 29 Si and 13 C MAS NMR and N 2 adsorption–desorption. The fluorescence properties of nanohybrids obtained have been correlated with the immobilization methods, generating interesting information concerning the localization of Fl–DFO molecules in the channels of mesoporous silica. The leaching of Fl–DFO molecules from mesoporous materials has been investigated. The nanosensor prepared by surface anchoring of Fl–DFO at the internal surface of mesochannels showed high performances with no leaching effect and high sensitivity in regards to its responses to ferric ions. Its fluorescence intensity decreased as soon as first Fe III ions are in contact with this nanosensor. A linear relationship between the fluorescence intensity and the ferric ions concentration was observed in low micromolar range. The selectivity of this nanosensor towards other metal ions has also been tested and shown its high affinity to ferric ions. This study can allow the design of a stable, portable, simple, regenerable and cost-effective nanosensor highly sensitive and selective for iron ions with detection limits in the range of cellular LIP in cells, e.g. lower micromolar range.
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