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1.
Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazardous gas components in air.
Different admixtures such as catalysts, aliovalent ions and solid ionic conductors were added to improve the sensitivity,
selectivity and stability of these sensors. For material preparation a sol-gel route is usually used and catalysts are added
before sintering to improve the sensitivity and to favour the sensors to specific gas components.
In this work we investigated the influence of added solid ionic conductors on the gas sensitivity of tin oxide based ceramic
admixtures dependent on the relative parts of the oxidic sodium ionic conductor, the ionic conductivity and the grain size
in relation to the tin oxide grains. Almost ideal model substances for these studies are solid electrolytes with the NASICON
(Na1+xZr2SixP3−xO12) structure. They can be prepared in the sol-gel route and in a solid state reaction as well resulting in different powder
grain sizes. The sodium ionic conductivity of the solid electrolytes in the composition range 0≤×≤3 varies by several orders
of magnitude.
Both materials, the NASICON and the tin oxide, were characterized with respect to morphology and structure by BET and XRD
measurements. Powders of tin oxide were homogeneously mixed with different NASICON powders, pressed as discs, sintered, and
contacted with gold electrodes for measurements of the conductivity in air at various temperatures (200°C≤T≤400 °C). For preparation
of sensor layers the powder mixtures were transferred to a paste, screen printed on an alumina substrate with interdigital
gold electrodes and sintered for gas sensitivity measurements. A dramatic sensitivity enhancement of the composite to alcohol
and significant sensitivity reduction to other gases like CO, H2, NH3, CH4, C3H8 was found.
Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001. 相似文献
2.
《Applied Surface Science》2002,185(3-4):161-171
The origin of haze was investigated in antimony-doped tin oxide thin films, and in double-stack thin films of fluorine-doped tin oxide/antimony-doped tin oxide, both deposited by chemical vapor deposition onto soda-lime–silica float glass substrates. These transparent conductive oxide thin films are of great importance in the production of solar control architectural glazing units. Therefore, understanding the origins of haze is necessary to the development of coated, IR-reflecting glass windows with low overall haze levels. Haze measurements of as-prepared and polished samples were correlated with surface roughness and concentration of internal hole defects. Surface roughnesses were evaluated by atomic force microscopy, and characterized by estimated RMS values. In thin tin oxide films (<2000 Å) internal hole defects caused haze, while in thick tin oxide films (>4000 Å) surface roughness was the primary source of haze. 相似文献
3.
The oxidation of liquid and solid tin from 25 to 240°C has been investigated using 75 eV low energy electron loss spectroscopy (LEELS) and Auger spectroscopy over an oxygen exposure range from zero to 107 L. LEELS was chosen for two reasons. First it can distinguish Sn, SnO and SnO2 from each other. Second, we show that at 75 eV incident energy LEELS has a penetration depth of only one monolayer. As a result the continuity and stoichiometry of the oxide layer could be studied as a function of thickness from submonolayer to several monolayer thicknesses. Although unable to distinguish SnO from SnO2 the larger penetration depth of the Auger technique complemented the LEELS study. From zero to one monolayer the oxide grows as islands containing both SnO and SnO2. Above one monolayer coverage the oxide is continuous and free of metallic tin with its outer most surface enriched in SnO2. Although oxide films grew more rapidly on polycrystalline tin than on single crystal tin the composition and continuity as a function of thickness remained unchanged. Very little change in oxide growth rate, continuity, or stoichiome- try was observed for solid tin up to temperatures near the melting point. However at 229°C, just 3°C below the melting point of tin, dissolution of oxygen into the metal was observed. A continuous, metal free solid oxide, primarily SnO, could be grown on liquid tin at 240°C than remained stable for 20 min after removal of the oxygen gas. Our model for the early stages of the oxidation of tin is different from that previously proposed on the basis of UPS, XPS, and 400 eV LEELS with respect to the continuity and relative ordering of the SnO and SnO2 phases. Quantitative comparison of our results with those previously reported shows that the previous results are consistent with our model for the structure and stoichiometry of the initial oxide grown on tin. 相似文献
4.
Diane Djoumessi Lekeufack Arnaud Brioude Yoann Lalatonne Laurence Motte Anthony W. Coleman Philippe Miele 《Journal of nanoparticle research》2012,14(6):1-7
The fabrication of semiconducting functional layers using low-temperature processes is of high interest for flexible printable electronics applications. Here, the one-step deposition of semiconducting nanoparticles from the gas phase for an active layer within a thin-film transistor is described. Layers of semiconducting nanoparticles with a particle size between 10 and 25?nm were prepared by the use of a simple aerosol deposition system, excluding potentially unwanted technological procedures like substrate heating or the use of solvents. The nanoparticles were deposited directly onto standard thin-film transistor test devices, using thermally grown silicon oxide as gate dielectric. Proof-of-principle experiments were done deploying two different wide-band gap semiconducting oxides, tin oxide, SnO x , and indium oxide, In2O3. The tin oxide spots prepared from the gas phase were too conducting to be used as channel material in thin-film transistors, most probably due to a high concentration of oxygen defects. Using indium oxide nanoparticles, thin-film transistor devices with significant field effect were obtained. Even though the electron mobility of the investigated devices was only in the range of 10?6?cm2?V?1?s?1, the operability of this method for the fabrication of transistors was demonstrated. With respect to the possibilities to control the particle size and layer morphology in situ during deposition, improvements are expected. 相似文献
5.
采用自悬浮定向流-真空热压法,在不同压强下制得铝纳米晶材料,并利用X射线衍射(XRD)和正电子湮没寿命谱(PALS)分析手段对铝纳米晶的结构和微观缺陷进行表征.XRD分析表明:所制备的铝纳米晶的晶粒度为48 nm.PALS分析表明:铝纳米晶的微观缺陷主要为类空位以及空位团,而微孔洞很少;短寿命τ1,中间寿命τ2以及其对应的强度I1,I2随压强变化而呈现阶段性变化;压制压强(P)低于0.39 GPa时制得的纳米晶空位团随压强的增加而逐渐转变为类空位;0.39 GPa P 0.72 GPa时,各类缺陷发生消除;P 0.72 GPa时,各类缺陷进一步发生消除.随压强的提高,铝纳米晶的密度增加,其显微硬度也明显增高. 相似文献
6.
Shumao Cui Eric C. Mattson Ganhua Lu Carol Hirschmugl Marija Gajdardziska-Josifovska Junhong Chen 《Journal of nanoparticle research》2012,14(3):744
Nanomaterials with controllable morphology and composition are synthesized by a simple one-step vapor condensation process
using a mini-arc plasma source. Through systematic investigation of mini-arc reactor parameters, the roles of carrier gas,
electrode material, and precursor on producing diverse nanomaterial products are revealed. Desired nanomaterial products,
including tungsten oxide nanoparticles (NPs), tungsten oxide nanorods (NRs), tungsten oxide and tin oxide NP mixtures and
pure tin dioxide NPs can thus be obtained by tailoring reaction conditions. The amount of oxygen in the reactor is critical
to determining the final nanomaterial product. Without any precursor material present, a lower level of oxygen in the reactor
favors the production of W18O49 NRs with tungsten as cathode, while a high level of oxygen produces more round WO3 NPs. With the presence of a precursor material, amorphous particles are favored with a high ratio of argon:oxygen. Oxygen
is also found to affect tin oxide crystallization from its amorphous phase in the thermal annealing. Results from this study
can be used for guiding gas phase nanomaterial synthesis in the future. 相似文献
7.
M.K. FungK.K. Wong X.Y. ChenY.F. Chan A.M.C. Ng A.B. Djuriši? W.K. Chan 《Current Applied Physics》2012,12(3):697-706
Indium oxide, tin oxide and indium tin oxide nanowires have been grown by vapor deposition on Si and quartz substrates. Under the growth conditions used, pure SiOx nanowires, a mixture of SiOx and indium oxide, tin oxide or indium tin oxide nanostructures, or pure indium oxide, tin oxide or indium tin oxide nanostructures could be obtained at different substrate temperatures. The growth mechanism of the obtained nanostructures at different substrate temperatures is discussed. Optical and electrical properties of the deposited pure indium oxide, tin oxide or indium tin oxide nanostructures have been measured, and low sheet resistances on quartz substrates have been obtained for indium oxide and indium tin oxide nanostructures. 相似文献
8.
V. S. Kortov K. A. Sergeeva V. A. Pustovarov A. A. Rempel 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2017,11(4):727-731
The photoluminescence of Zn2SiO4:Mn2+ ceramics with a particle size of 120 ± 10 nm, which is excited in the range of 3.5–5.8 eV and subjected to synchrotron radiation with photon energies of up to 20 eV, is investigated. Nanoscale Zn2SiO4:Mn2+ ceramics possesses intense luminescence with a maximum of 2.34 eV, the position and half-width of the band are independent of the excitation energy. It is found that the photoluminescence at 2.34 eV decays nonexponentially upon ultraviolet excitation. In the case of nanoscale ceramics is irradiated by vacuum ultraviolet, an additional photoluminescence-excitation channel is likely to occur due to interaction of band states and intrinsic vacancy-like defects of the Zn2SiO4 matrix. 相似文献
9.
Effects of Additional Vacancy-Like Defects Produced by Ion Impealations on Boron Thermal Diffusion in Silicon
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The effects of additional vacancy-like defects on thermal diffusion of B atoms in silicon were investigated by using secondary ion mass spectroscopy. B atoms were introduced into silicon by 30keV B ion implantation at a dose of 2×1014cm-2, while the additional vacancy-like defects were produced by two different ways. One was via 40 or 160keV He ion implantation at a dose of 5×1016cm-2 and followed by an annealing at 800°C for 1h, which produced a well-defined cavity band near the projected range of He ions. The other was via 0.5MeV F or O ion implantation at a dose of 5×1015cm-2,which creates excess vacancy-like defects around the 1/2 projected range of F or O ions. Our results clearly show that the additional vacancy-like defects could suppress the boron diffusion during subsequent thermal annealing at 800°C for 30 min. The suppressing effects were found to depend on both the ion type and ion energy. The results were qualitatively discussed in combination with the results obtained by using transmission electron microscopy and Rutherford backscattering spectroscopy. 相似文献
10.
N. Sankara Subramanian B. Santhi T. Sornakumar G. Karthik Subbaraj C. Vinoth G. Murugan 《Ionics》2004,10(3-4):273-282
Undoped and antimony doped tin oxide thin films of different thicknesses were prepared on mineral glass substrate by spray
pyrolysis method via sol-gel route. Both the films show good transmittance in the visible region. Band gap energy of both
films lies between 3 to 3.5 eV. X-ray diffraction studies of undoped and antimony doped tin oxide thin films for various annealing
temperature show polycrystalline tetragonal structure of SnO2 with preferred orientation of (110) and (101), respectively and from the XRD data, grain size were also evaluated. AFM images
of Undoped and antimony doped tin oxide thin films annealed at 375 °C depict the film thickness and indicate uniform surface
pattern without dark pits and with strains of some ups exceeding the specified limit. The prepared films were tested in a
specially developed test rig for Liquefied Petroleum Gas detection at different operating temperatures. The response characteristics
of the films for LPG detection show maximum sensitivity and minimum response time at the operating temperature 400 °C. Studies
indicate that antimony doped tin oxide thin film are one among the suitable candidates for LPG detection with a detection
sensitivity and response time (t90) of 11 and 140 seconds, respectively.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
11.
Indium-tin oxides (ITO) films were prepared on glass by Ar ion sputtering, ion plating and electron beam melting in vacuum,
and tin oxide films were prepared by chemical vapour deposition (CVD) of SnCl4 in methanol containing HF. The chemical state of samples prepared was analyzed by CEMS. ITO films, produced from ITO source
materials with higher solubility of tin oxide, showed lower electric resistivity. Amorphous ITO films had larger quadrupole
splitting than crystalline ones. The tin oxide films were exposed in hydrogen plasma and hydrogen gas and the change of these
films was also assessed by CEMS. 相似文献
12.
Tin oxide was supported on aluminium oxide, titanium oxide, magnesium oxide and silicon oxide, and the resulting interactions between the components in the prepared samples and after reduction were characterized by Mössbauer spectroscopy. It was observed that in the oxide state, tin is present as SnO2 on alumina, magnesia and silica, but on titania tin occupies Ti sites in the structure. After hydrogen treatment at high temperatures, tin is reduced from Sn(4) to Sn(2) on alumina and titania; it is reduced from Sn(4) to Sn(0) on silica, and is practically not reduced on magnesia. These results reveal the degree of interaction between tin and the different supports studied. 相似文献
13.
In this work, the influence of synthesis parameters on the synthesis efficiency of tin oxide nanomaterials was studied by
using the carbothermal reduction method in a sealed tube furnace. The parameters were the starting material, temperature and
time of synthesis as well as the gas flux. The starting material was tin dioxide mixed with carbon black in a molar proportion
of 1.5:1 and 1:1. The temperature range was from 950 to 1,125 °C with a step of 25 °C, and the synthesis times used were 15,
30, 45, 60, 75, 90, and 120 min. Using optimum values of the above parameters, the gas flux was changed to verify its influence.
After completion of the syntheses, we found a grayish-black material inside the tube which was characterized by X-ray diffraction
and scanning electron microscopy. The results showed that the collected material is composed of nanobelts (with width around
60 nm) and disks that grew preferentially in the SnO phase. A model based on the oxide vapor pressure was proposed to evaluate
the efficiency of the process, and the results showed good agreement between experimental data and the proposed model. Based
on the results obtained, the best conditions to obtain a homogeneous material with 95% efficiency is using a starting material
in the molar proportion Sn:C of 1.5:1, a temperature of 1,132 °C for 75 min, and a N2 gas flux of 80 sccm. 相似文献
14.
《Current Applied Physics》2020,20(5):720-737
Roll-to-roll (R2R) production is an innovative approach and is fast becoming a very popular industrial method for high throughput and mass production of solar cells. Replacement of costly indium tin oxide (ITO), which conventionally has served as the transparent electrode would be a great approach for roll to roll production of flexible cost effective solar cells. Indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) are brittle and ultimately limit the device flexibility. Perovskite solar cells (PSCs) have been the centre of photovoltaic research community during the recent years owing to its exceptional performance and economical prices. The best reported PSCs fabricated by employing mesoporous TiO2 layers require elevated temperatures in the range of 400–500 °C which limits its applications to solely glass substrates. In such a scenario developing flexible PSCs technology can be considered a suitable and exciting arena from the application point of view, them being flexible, lightweight, portable, and easy to integrate over both small, large and curved surfaces. 相似文献
15.
Pure and Au-doped mesostructured SnO2 thin films were successfully prepared by using non-ionic surfactant Brij-58 (polyoxyethylene acyl ether) as organic template and tin tetrachloride and hydrogen tetrachloroaurate(III) trihydrate as inorganic precursor. Thin films were deposited onto the glass substrates at 450 °C by simple spray pyrolysis technique. The novel mesostructured tin oxide thin films with different Au concentration exhibit highly selective response towards CO. The correlation of the Au incorporation in the mesostructure with particular morphology and gas sensing behavior is discussed using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area and transmission electron microscopy (TEM) studies. 相似文献
16.
J. Cizek I. Prochazka N. Zaludova G. Brauer A. Mücklich R. Kirchheim 《Applied Surface Science》2008,255(1):251-253
The present work reports on microstructure investigations of hydrogen-loaded nanocrystalline Gd films by means of slow positron implantation spectroscopy combined with in situ synchrotron radiation X-ray diffraction. It is found that the virgin films contain a high density of vacancy-like open volume defects at grain boundaries which trap positrons. These defects represent trapping sites also for hydrogen. With increasing hydrogen concentration the transformation from the α- into the β-phase (GdH2) takes place in the film. Accumulation of hydrogen at grain boundaries causes a decrease of positron localization at defects. The transformation into the β-phase is completed at xH ≈ 1.6 H/Gd. Contrary to bulk Gd specimens, the γ-phase (GdH3) is not formed in the nanocrystalline Gd films. 相似文献
17.
采用脉冲激光沉积方法在(LaAlO3)0:3(Sr2AlTaO6)0:7衬底上外延生长了La0.7Sr0.3MnO3薄膜,并采用慢正电子束方法分析了薄膜在不同厚度和不同退火气氛下参数S的变化. 分析表明,薄膜中包含两种机制引入的氧空位,分别是薄膜生长气氛中氧压偏低造成薄膜的氧缺乏和由于薄膜应变引入空位型缺陷. 当薄膜厚度较薄时,应变造成的晶格畸变化比较大,当薄膜的厚度大于11 nm时,薄膜的应变驰豫已经比较完全. 原位退火的样品中正电子主要是被氧缺乏引起的氧空位捕获. 在氧气中退火的样品,S随厚度的变化反映了应变对薄膜微结构的影响. 相似文献
18.
《Surface science》1996,367(2):L47-L53
Scanning tunneling microscopy (STM) is used to study surface diffusion of a special type of point defects at Si(111)-7 × 7 surfaces. These defects survive even after annealing up to 1250°C. They appear darker than Si adatoms at the tunneling biases ranging from −3 to +3 V, but they are not true vacancies. We found that these vacancy-like defects (hereafter, we refer to them as pseudo-vacancies) are not caused by adsorption of major contaminants in the vacuum chamber, nor by dopants. We also observed migration of pseudo-vacancies between nearest neighboring Si adatom sites at temperatures above 500°C. Most of the jumps are within a half of the 7 × 7 unit cell. Thousands of STM images were recorded from 520 to 610°C and the activation energies and frequency factors were determined. Varying the tunneling current produces almost no effect on the diffusion, but varying the scanning speed produces a small effect. 相似文献
19.
Ferenc Somodi Irina Borbáth József L. Margitfalvi Sándor Stichleutner Károly Lázár 《Hyperfine Interactions》2009,192(1-3):13-21
The active catalytic components in tin oxide containing alumina-supported gold catalyst were examined by comparing and analysing the in situ Mössbauer spectra of the SnO x –Al2O3 support and the 3 wt.% Au/SnO x –Al2O3 catalyst (1.1 wt.% Sn, Au/Sn = 3:2 atomic ratio). Samples were prepared by using organometallic precursor of 119SnMe4 (enriched). First tin was grafted to the alumina surface from the organometallic precursor compound. In the next step the grafted complexes were decomposed in flowing oxygen. Gold was deposited onto the SnO x –Al2O3 support in the subsequent step. Analysis of in situ spectra shows that in Au/SnO x –Al2O3 catalyst after activation in hydrogen at 620 K tin may occur in three different oxidation states [Sn (IV), Sn(II) and Sn(0)] simultaneously. The metallic tin is a component of the bimetallic AuSn alloy phase. Data presented provide the first evidence for the formation of alloy-type supported Sn–Au catalyst on alumina. Furthermore, from the spectra recorded at different temperatures, values of the Debye temperatures and recoilless fractions were also determined for the various species. The results show that in catalytic oxidation of carbon monoxide at room temperature the dominant part of Sn(II) and the AuSn alloy is oxidized. 相似文献
20.
J. Yli-Kauppila P. Moser H. Kiinzi P. Hautojdrvi 《Applied Physics A: Materials Science & Processing》1982,27(1):31-33
Positron lifetime measurements were performed on amorphous Pd80Si20 and Cu50Ti50 alloys irradiated with 3MeV electrons at 20K. The irradiation was found to increase the mean positron lifetime in both specimens indicating the presence of vacancy-like radiation damage. Isochronal annealing between 77 K and 300 K resulted in a continuous reduction of the positron lifetime, which suggests a gradual recovery of the irradiation induced defects. 相似文献