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1.
SnO2 nanowires mixed nanodendrites for high ethanol sensor response   总被引:1,自引:0,他引:1  
Mixed morphology of SnO2 nanowires and nanodendrites was synthesized on the gold-coated alumina substrates by carbothermal reduction of SnO2 in closed crucible. The products were characterized by scanning electron microscopy, x-ray diffractometer, and transmission electron microscopy. Results showed the SnO2 nanowires and the SnO2 nanodendrites branched out from the main nanowires. Both SnO2 nanostructures were pure tetragonal rutile structure. The nanowires were grown in [101] and directions with the diameter of 50–150 nm and the length of a few 10 μm. The nanodendrites were about 100–300 nm in diameter. The growth mechanism of the SnO2 nanostructures was also discussed. Characterization of ethanol gas sensor, based on the mixed morphology of the SnO2 nanostructures, was carried out. The optimal temperature was about 360 °C and the sensor response was 120 for 1000 ppm of ethanol concentration.  相似文献   

2.
Large-scale synthesis of rutile SnO2 nanorods   总被引:1,自引:0,他引:1  
A high yield of tin oxide (SnO2) nanorods was obtained via annealing a nanoscale precursor in the molten salt flux and surfactant. X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction and infrared spectroscopy showed that the nanorods are composed of SnO2 with rutile structure. The surfactant and temperature have a profound influence on the production of SnO2 nanorods.  相似文献   

3.
In this study, SnO2/TiO2 thin films are fabricated on SiO2/Si and Corning glass 1737 substrates using a R.F. magnetron sputtering process. The gas sensing properties of these films under an oxygen atmosphere with and without UV irradiation are carefully examined. The surface structure, morphology, optical transmission characteristics, and chemical compositions of the films are analyzed by atomic force microscopy, scanning electron microscopy and PL spectrometry. It is found that the oxygen sensitivity of the films deposited on Corning glass 1737 substrates is significantly lower than that of the films grown on SiO2/Si substrates. Therefore, the results suggest that SiO2/Si is an appropriate substrate material for oxygen gas sensors fabricated using thin SnO2/TiO2 films.  相似文献   

4.
We report the preparation of a novel kind of α-Fe2O3 hollow core/shell hierarchical nanostructures self-assembled by nanosheets. A green precursor powder is first prepared using nontoxic and inexpensive FeCl3 and urea in ethylene glycol by a surfactant-free solvothermal method at 160 °C for 15 h. The α-Fe2O3 hollow core/shell hierarchical nanostructures are obtained by the thermal treatment of the green precursor powder. The as-prepared α-Fe2O3 hollow core/shell hierarchical nanostructures are porous, and exhibit a good photocatalytic activity for the degradation of phenol. The samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).  相似文献   

5.
Structural and morphological characteristics of (1−x)α-Fe2O3-xSnO2 (x=0.0-1.0) nanoparticles obtained under hydrothermal conditions have been investigated by X-ray diffraction (XRD), transmission Mössbauer spectroscopy, scanning and transmission electron microscopy as well as energy dispersive X-ray analysis. On the basis of the Rietveld structure refinements of the XRD spectra at low tin concentrations, it was found that Sn4+ ions partially substitute for Fe3+ at the octahedral sites and also occupy the interstitial octahedral sites which are vacant in α-Fe2O3 corundum structure. A phase separation of α-Fe2O3 and SnO2 was observed for x≥0.4: the α-Fe2O3 structure containing tin decreases simultaneously with the increase of the SnO2 phase containing substitutional iron ions. The mean particle dimension decreases from 70 to 6 nm, as the molar fraction x increases up to x=1.0. The estimated solubility limits in the nanoparticle system (1−x)α-Fe2O3-xSnO2 synthesized under hydrothermal conditions are: x≤0.2 for Sn4+ in α-Fe2O3 and x≥0.7 for Fe3+ in SnO2.  相似文献   

6.
We focused on the effects of the inorganic acid HNO3 on the gas-sensing properties of nanometer SnO2 and prepared the powders via a dissolution-pyrolysis method. Furthermore, the powders were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectra (EDS). Several aspects were surveyed, including the calcining temperature, concentration of nitric acid and the working temperature. The results showed that the gas response of 3 wt% HNO3-doped SnO2 powders (calcined at 500 °C) to 10 ppm Cl2 reached 316.5, at the working temperature 175 °C. Compared with pure SnO2, appropriate HNO3 could increase the gas sensitivity to Cl2 gas more significantly.  相似文献   

7.
A study on the low-temperature CO gas sensors based on Au/SnO2 thick film was reported. Au/SnO2 powders were prepared by a deposition-precipitation method. Thick films were fabricated from Au/SnO2 powders. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analyses were carried out for investigation of morphology and crystalline structure. Au/SnO2 thick film sensors exhibited high sensitivity to CO gas at relatively low operating temperature (83-210 °C). We also reported the effect of the calcination temperature of Au/SnO2 on the CO gas sensing behavior. The optimal calcination temperature of Au/SnO2 was 300 °C.  相似文献   

8.
SnO2/In2O3 one-dimensional nano-core-shell structures have been synthesized at 1350 °C by thermal evaporation of the mixture of metal Sn, Fe(NO3)3 powders and In particles. The as-synthesized products have been characterized by energy-dispersive X-ray spectroscopy, selected-area electron diffraction and high-resolution transmission electron microscopy. Microstructure characterization indicates the orientation relationship between core and shell is , . The formation mechanism of this nano-core-shell structure can be attributed to the cover of In2O3 on the surface of SnO2 nanochains. The photoluminescence properties of the nano-core-shell structures have been measured. The PL spectrum shows some difference with the result from pure SnO2 and In2O3 nanostructure that be deemed to relate to interface defects in SnO2/In2O3 nano-core-shell structure.  相似文献   

9.
Tin oxide (SnO2)-layers-doped terbium and europium ions are elaborated by the sol-gel method on silicon substrates. After annealing at 500 °C, the transmission electron microscopy revealed a crystallization of tin oxide.The emission properties of rare-earth in SnO2 are studied systematically against temperature annealing and Tb3+ concentration. The PL spectrum is optimal after annealing at 900 °C and the corresponding photoluminescence (PL) decay is nearly exponential, showing that the sample is homogenous and the PL process can be described by two levels system.The concentration effect shows a quenching of the PL intensity for Tb3+ concentration above 4%. From the investigation of the decay rate from the 7F5 state within terbium concentration, we show that self-quenching is insured by dipole - dipole interaction. The evolutions of both PL intensity and PL lifetime versus temperature are studied. The PL intensity and PL lifetime are enhanced by deposing SnO2:Tb3+ and SnO2:Eu3+ in porous silicon. We show that an efficient excitation transfer from Si nanocrystallites to RE ions can occur.  相似文献   

10.
Nb2O5 nanorods have been prepared using water/ethanol media. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible absorption and photoluminescence spectroscopy. The as-prepared Nb2O5 nanorods appeared to be single pseudohexagonal (TT-Nb2O5) phase. From the photoluminescence spectrum, two emission bands at 407 and 496 nm, respectively, were observed. The origin of the luminescence was discussed in detail.  相似文献   

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