共查询到20条相似文献,搜索用时 0 毫秒
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G. Velayutham C. Ramesh N. Murugesan V. Manivannan K. S. Dhathathreyan G. Periaswami 《Ionics》2004,10(1-2):63-67
A Nafion based amperometric hydrogen sensor that operates at room temperature has been developed. The electrolyte used in
the sensor is Nafion 117, which is a proton conducting solid polymer electrolyte. Palladium catalyst was used on the sensing
side and platinum supported on carbon on the air side. The sensor functions as fuel cell, H2/Pd//Nafion//Pt/O2 and the short circuit current is measured. The short circuit current is found to be linear with respect to concentration
of hydrogen on the sensing side. The sensor is able to detect the concentration of hydrogen in argon down to ppb level. Details
of assembly of the sensor, response behavior and applications are discussed.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
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We report a novel scheme for a fiber-optic hydrogen sensor based on an erbium-doped fiber laser with a palladium-coated tapered fiber within the laser cavity. The tapered fiber acts as a hydrogen-sensing element. When the sensing element is exposed to a hydrogen atmosphere, its attenuation decreases, changing the cavity losses and leading to a modification of the laser transient. The hydrogen concentration is obtained by simple measurement of the buildup time of the laser. This technique translates the measurement of hydrogen concentration into the time domain, and it can be extended to many intensity-based fiber sensors. Relative variations in the buildup time of up to 55% at an increase of the hydrogen concentration from 0 to 10% are achieved with a resolution of better than 0.1%. 相似文献
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将钯基材料对氢气分子的特异选择性吸附能力与声表面波的快速响应特点相结合,可实现一种快速、高灵敏和低功耗的氢气检测与报警技术。传感器由双通道差分式振荡器与沉积在传感器件表面的声表面波传播路径上的钯基气敏薄膜组成。为提升传感器响应速度,该文探讨了采用钯镍合金薄膜与钯铜纳米线作为气敏材料的氢气传感器响应特性,通过对气敏材料制备方法及参数的优化,研制了两种沉积不同钯基气敏材料的氢气传感器件,并对其性能进行了评测。实验测试结果表明:钯铜纳米线气敏材料由于具有大体积表面积比和多孔结构,大幅提高了SAW氢气传感器响应速度,针对浓度为10%、4%以及0.5%的氢气响应时间可达~2s。 相似文献
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The layered hydrate HUO2PO4·4H2O is known to be a good selective proton conductor at room temperature. We have shown that the conductivity is dependent on the pressure of water vapour and good long term stability is obtained even at current densities as high as 5 mA/cm2. The construction of porous composite electrodes of Pt and Pd is described and their use in hydrogen concentration cells is demonstrated. Furthermore, it is shown that these concentration cells give the correct voltage according to Nernst's law. 相似文献
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C. Ramesh G. Velayutham N. Murugesan V. Ganesan V. Manivannan G. Periaswami 《Ionics》2004,10(1-2):50-55
An improved polymer electrolyte membrane (PEM) fuel cell based amperometric hydrogen sensor that operates at room temperature
has been developed. The electrolyte used in the sensor is PVA/H3PO4 blend, which is a proton conducting solid polymer electrolyte. A blend of palladium and platinum coated on the membrane is
used as anode and platinum as cathode. The sensor functions as a fuel cell, H2/Pd-Pt//PVA-H3PO4//Pt/O2, and the short circuit current is found to be linearly related to the hydrogen concentration. The present study aims at investigating
the dependence of sensor behaviour on the anode composition.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
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Joanna Prażmowska Adam Szyszka Regina Paszkiewicz Marek Tłaczała 《Central European Journal of Physics》2011,9(2):398-403
In this paper, a study of the influence of hydrogen (concentrations 6 ppm − 1%) on the work function of thin metallic films
at moderately elevated temperatures is presented. The work function was measured indirectly by the observation of the surface
potential of dedicated test structures using scanning surface potential microscope. Metallic layers with thicknesses of 10,
20, 30, and 50 nm were deposited on semiconductor substrates as well as on a thick gold layer. The investigations were focused
on palladium thin films although a comparison to results obtained for platinum layers was also discussed. 相似文献
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Howie RT Guillaume CL Scheler T Goncharov AF Gregoryanz E 《Physical review letters》2012,108(12):125501
We used Raman and visible transmission spectroscopy to investigate dense hydrogen (deuterium) up to 315 (275) GPa at 300 K. At around 200 GPa, we observe the phase transformation, which we attribute to phase III, previously observed only at low temperatures. This is succeeded at 220 GPa by a reversible transformation to a new phase, IV, characterized by the simultaneous appearance of the second vibrational fundamental and new low-frequency phonon excitations and a dramatic softening and broadening of the first vibrational fundamental mode. The optical transmission spectra of phase IV show an overall increase of absorption and a closing band gap which reaches 1.8 eV at 315 GPa. Analysis of the Raman spectra suggests that phase IV is a mixture of graphenelike layers, consisting of elongated H2 dimers experiencing large pairing fluctuations, and unbound H2 molecules. 相似文献
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《Current Applied Physics》2018,18(3):273-279
Oligo(phenylene ethynylene) (OPE) molecular junction has been suggested as a H2 molecule sensor based on calculations using the first principles of density–functional theory and non-equilibrium Green's function. The electronic transport properties of the OPE molecule between two Au electrodes with or without adsorbed H2 molecules are investigated. Results show that the adsorbed H2 molecule significantly changes the characteristics of the current–voltage curve of the OPE molecular junction. The pure OPE molecular junction exhibits a significant negative differential resistance, but this kind of phenomenon will disappear or weaken after hydrogen molecules are adsorbed. The conductance of the junction also obviously decreases in the bias range of [−0.4, 0.4] V after adsorbing H2 molecules. These effects can be used to design a H2 molecule sensor. 相似文献
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A mixed potential type yttria-stabilized zirconia-based sensor using NiO sensing electrode and Pt reference electrode was fabricated, and its NO2 sensing characteristics were examined at various operating temperatures in the range of 700–950 °C. It was observed that the sensitivity to NO2 strongly depends on the operating temperature of the sensor; the sensitivity decreases with increasing operating temperature, while the response/recovery rates increase. To rationalize this temperature dependence of NO2 response, polarization curves and complex impedances of the sensor were measured in the base gas and in the sample gas (400 ppm NO2?+?base gas) at various operating temperatures. It turned out that the operating temperature had a strong influence on the rate of anodic reaction of oxygen; the increased rate of anodic reaction leads to lower NO2 sensitivity and quicker response/recovery at higher operating temperature. 相似文献
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Paolo Vanini 《Letters in Mathematical Physics》1994,32(4):331-346
We consider the Schrödinger equation with an even-square integrable potential of period one on the negative real axis and a wall potential of heighta > 0 on the positive real axis. The spectrum of this Schrödinger equation is determined and it is proved that bounded solutions never exist if the energyE < a is lying in a gap of the periodic spectrum. 相似文献
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论述了一种非本征法布里 珀罗光纤应变传感器。采用透明弹性聚合物薄膜作为法布里 珀罗干涉腔,聚合物固定在多膜光纤末端作为应变敏感元件。传感器的分辨率为2μm,测量精度在0~5000μm范围内为5μm。 相似文献
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It was investigated whether a perovskite-type proton conductor, here BaCe0.95Y0.05O3 − δ (BCY), is suitable as sensing material for a novel type of thermoelectric hydrogen sensor. Therefore, the hydrogen and oxygen concentration dependence of the thermopower of BaCe0.95Y0.05O3 − δ was determined and was found to be in the same range as the value derived from theory. The hydrogen dependence was also measured at different temperatures, and only a comparatively small temperature dependence of the thermopower was observed. 相似文献
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Transverse magnetic (TM) waves in a four-layer slab waveguide structure are studied for optical sensing applications. The structure consists of a semi-infinite substrate, a thin metal layer, a medium with negative permittivity and permeability as a guiding layer, and a semi-infinite layer as a cover. The proposed sensor is operated in reflection mode in which the angular position of the reflectance peak is used to detect small changes in the refractive index of the cover medium. The optimal structure parameters that correspond to the sharpest and highest peak are presented. The results reveal that for aluminum metal layer, a thickness of about 9 nm represents the optimum metal thickness. Moreover, the thickness, negative permittivity, and negative permeability of the guiding layer are found to have great impacts on the performance of the proposed optical waveguide sensor. 相似文献
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双套管式光纤Bragg光栅温度传感器 总被引:3,自引:0,他引:3
研制了一种双套管式光纤Bragg光栅温度传感器,以实现无外力作用的温度测量。其中外套管隔离外加应力应变,在内套管内松弛地放置光栅以隔离封装结构的表观热应变。引入引出尾纤穿过带孔螺栓,以探测多个串联光栅。为了避免光栅处于张拉状态,封装在外套管1、外套管2和内套管中的光纤余长应分别大于1.4mm,1.8mm和0.4mm。试验结果表明,该光栅传感器的温度响应灵敏度为9.671×10-3nm/℃,温度测量分辨率为0.1℃。当水温从20℃跃变到70℃时,该传感器的温度响应时间分别为t0.5=15±2s和t0.9=52±4s。当水温从70℃跃变到20℃时,该传感器的温度响应时间分别为t0.5=26±9s和t0.9=63±8s。 相似文献
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Clustering of Ti on carbon nanostructures has proved to be an obstacle in their use as hydrogen storagematerials. Using density functional theory we show that Ti atoms will not cluster at moderate concentrations when doped into nanoporous graphene. Since each Ti atom can bind up to three hydrogen molecules with an average binding energy of 0.54 eV/H2, this material can be ideal for storing hydrogen under ambient thermodynamic conditions. In addition, nanoporous graphene is magnetic with or without Ti doping, but when it is fully saturated with hydrogen, the magnetism disappears. This novel feature suggests that nanoporous graphene cannot only be used for storing hydrogen, but also as a hydrogen sensor. 相似文献
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Oxygen dependency of the hydrogen sensor using high-temperature proton conductors with titanium/titanium hydride solid reference
material was studied. It was found that the oxygen in a measuring atmosphere led to a considerable p-type conduction which
was responsible for the instability of the sensor electromagnetic field (EMF). The sensor EMF increased continuously due to
the insertion of protons and decreased due to the depletion of protons upon exposure to an oxidizing atmosphere. It is revealed
that the EMF behavior of the sensor is decided by the electronic conduction that relatively changed with hydrogen concentration
in a highly oxidizing atmosphere. The transient behavior of the hydrogen sensor under various atmospheres containing oxygen
was discussed in this work. 相似文献
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We have studied a ferromagnetic superconductor having both a magnetic domain structure of the Kittel-type and a laminar structure of the normal regions. Our phenomenological approach is a combination of Ginzburg-Landau theory for superconductivity and the microscopic theory of ferromagnetism. Calculations of the thermodynamical potential and a comparison with Meissner and normal states offer the possibility to predict conditions for the crystal thickness and/or the absolute value of the magnetization vector at which the “mixed” state can exist. 相似文献