共查询到20条相似文献,搜索用时 15 毫秒
1.
Narender Budhiraja Sapna Vinod Kumar Monika Tomar Vinay Gupta 《Integrated ferroelectrics》2018,193(1):59-65
AbstractPresent work reports on the synthesis of 2-dimensional (2D) CuO nanostructures with enhanced NO2 gas sensing properties by a facile solvothermal method. 2D CuO nanostructures were investigated using X-ray diffraction, Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). FESEM studies revealed as synthesized nanostructures possess a nanosheets like morphology. Gas sensing studies showed that sensor of as prepared 2D CuO nanostructures exhibit enhanced gas sensing properties with excellent selectivity towards NO2 as compared to other volatile gases such as ethanol, methanol and acetone. 相似文献
2.
Avneet Singh Anjali Sharma Nidhi Dhull Anil Arora Monika Tomar 《Integrated ferroelectrics》2018,193(1):72-87
AbstractIn the present work efforts have been made to develop microheater integrated gas sensors with low power consumption. The design and simulation of a single-cell microheater is carried out using ANSYS. Low power consumption (<35?mW) platinum micro-heater has been fabricated using bulk micromachining technique on silicon dioxide membrane (1.5?μm thin), which provided improved thermal isolation of the active area of 250?×?250?μm2. The micro-heater has achieved a maximum temperature of ~950?°C at an applied dc voltage of 2.5 V. Fabricated mircro-heater has been integrated with SnO2 based gas sensors for the efficient detection of H2 and NO2 gases. The developed sensors were found to yield the maximum sensing response of ~184 and ~2.1 with low power consumption of 29.18 and 34.53?mW towards the detection of 1?ppm of NO2 gas and 500?ppm of H2 gas, respectively. 相似文献
3.
This work presents a simple synthetic route to produce WO3 nanofibers functionalized by catalytic Pt and IrO2 nanoparticles and their superior acetone and H2S sensing characteristics, demonstrating the potential use of Pt and IrO2 nanoparticles in applications as sensors of biomarkers of diabetes and halitosis, respectively, in exhaled breath. The individual WO3 fiber, calcined at 500 °C, was composed of small nanoparticles with a size distribution in the range of 30?C100?nm. Networks of WO3 fibers exhibited a high surface-to-volume ratio and unique morphologies, thus facilitating efficient gas transport into the entire fiber layers. Pt (4?C7?nm) and Ir (4?C8?nm) nanoparticles were synthesized by polyol methods and were used as additives to decorate the surface of the WO3 fibers. After a heat treatment, those catalyst particles were partially or fully oxidized to Pt/PtOx and IrO2, respectively. To investigate the advantages of Pt-decorated WO3 fibers (Pt-WO3) and IrO2-decorated WO3 (IrO2-WO3) fibers as acetone (CH3COCH3) and H2S sensing materials, respectively, we carried out gas-sensing measurements in a highly humid atmosphere (RH 75?%) similar to that of an oral cavity. The Pt-WO3 fibers showed a high acetone response (Rair/Rgas?=?8.7 at 5?ppm) at 350?°C and a superior H2S response (Rair/Rgas?=?166.8 at 5?ppm) at 350?°C. Interestingly, IrO2-WO3 fibers showed no response to acetone, while the gas response to H2S exhibited temperature-insensitivity, which has never been reported in any other work. Thus, the highly selective cross-response between H2S and acetone was successfully achieved via the combination of IrO2 particles on WO3 fibers. This work demonstrates that accurate diagnosis of diabetes and halitosis by sensing exhaled breath can be realized through the use of electrospun WO3 fibers decorated with Pt and IrO2 catalysts. 相似文献
4.
Shiguang Shang Ling Zhao Xin Li Mingqi Gao Ping Zhao Shan Zhao 《Integrated ferroelectrics》2014,151(1):49-55
The tungsten trioxide (WO3) precursor was prepared by sol-gel method with tungsten powder as the raw material, and the WO3 gas sensing films were obtained by a dip coating method and annealing precursor in air. X-ray diffraction (XRD) spectra indicate that with increasing annealing temperature the triclinic structure of as-prepared sample was transformed into monoclinic or orthorhombic phase. The images of scanning electron microscopy (SEM) exhibit that the WO3 grain sizes increase from less than 100 nm to several micrometers with increasing annealing temperature. The influences of applied frequency, annealing and operating temperature on NH3 gas sensing properties of the nanostructured WO3 porous films were investigated. The results indicate that the gas sensing film annealed at 500°C express high sensitivity, fast response and recovery speed to NH3 at operating temperature 250°C. 相似文献
5.
Marija F. Hribek Slavica S. Risti Bojana M. Radojkovi Zoran Lj. Filipovi Ognjen R. Risti 《International Journal of Numerical Modelling》2013,26(3):263-274
Comparative analysis of different, new gas sensing materials in surface acoustic wave chemical sensors is presented. Different gas sensing materials as polyaniline (PANI), Teflon AF 2400, polyisobutylene (PIB), polyepichlorohydrin (PECH) are considered. They are chosen according to the type of gas to be detected and the desired accuracy: Teflon AF 2400 thin film for the detection of CO2, PANI nanocomposites film that belongs to the group of conductive polymers for the detection of CO, NO2 and phosgene (COCl2), and PECH and PIB for the detection of dichloromethane (CH2Cl2, DCM). In the analysis, the simple and useful method of the complete analyses of gas chemical sensors is used. The method is based on the electrical equivalent circuit of the surface acoustic wave sensor. The method is very efficient and can be used for the optimal design of CO2 sensors. The results are compared with those presented in public literature and good agreement is obtained, demonstrating the validity of modelling. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
6.
Abstract High sensitive pyroelectric infrared (IR) sensors have been fabricated by using c-axis oriented La-modified PbTiO3 (Pb1–xLaxTi1?x/4O3, PLT) thin films. The PLT thin films were deposited on (100)-cleaved MgO single crystal substrates by intermittent rf-magnetron sputtering method. The PLT thin films have high figures of merit for IR sensor without a poling treatment. High performance pyroelectric IR sensors (single element type and linear array type) were fabricated by using PLT (x=0·1, γ=5·5x10?8 C/cm2K, ?r=200) thin films. The sensors have remarkably high D* of 3–6x108 cmHz1/2/W and very fast response. A new compact IR sensing system using the linear array sensor (8 elements) has been developed for a new type of room air-conditioner. This system can measure thermal distribution (8x64) by horizontal scanning of the vertical linear array. Image processing with neural network concept makes possible high-accuracy using a few data from the sensor elements. This sensing system provides ‘‘smart airconditioning'’to improve the comfortable control. 相似文献
7.
Growth and Dielectric Properties of Ferroelectric BaTiO3 Thin Films for Cantilever-Type Microsensors
Eun-Kyoung Kim Sung-Q Lee Seung Eon Moon Su-Jae Lee Kang-Ho Park 《Integrated ferroelectrics》2013,141(1):349-355
ABSTRACTFerroelectric BaTiO3 (BTO) thin films were deposited on Si, silicon-on-insulator (SOI) and MgO substrates by pulsed laser deposition. The orientations of the films, polycrystalline and epitaxial phase, were controlled by the lattice mismatch between the BTO film and substrates. The structural properties and surface morphologies were examined using X-ray diffractometer and atomic force microscope. The dielectric properties of BTO films were investigated using metal-ferroelectric-metal (MFM) and interdigital co-planar capacitors. Conductive oxide layers, SrRuO3(SRO) and La0.5Sr0.5CoO3 (LSCO), were grown on Si and SOI substrates as bottom electrodes. For MFM capacitors based on Au/BTO/SRO/Si and Au/BTO/LSCO/SOI layer structures, a little asymmetric capacitance-voltage curves were obtained with about 36% capacitance tunability. The remanent polarizations were about 21 μC/cm2 and the coercive fields were about 71 kV/cm. For an interdigital capacitor based on Au/BTO/MgO layer structure, a little lossy capacitance-voltage curve was obtained with about 64% capacitance tunability. 相似文献
8.
C. Pijolat C. Pupier C. Testud R. Lalauze L. Montanaro A. Negro C. Malvicino 《Journal of Electroceramics》1998,2(3):181-191
Recent progress in the development of a -alumina gas sensor for automotive applications is reported. The sensing device consists of two solid electrolytes (namely a thin film of sodium sulfate deposited on -alumina by appropriate treatment in a gaseous atmosphere), with two electrodes having different catalytic properties, one made of platinum, the other of gold. The -alumina component was prepared as sintered pellets by pressing and as thick films by screen-printing. The electrical response of these materials at different temperatures in the range 300° to 800°C and under various gases (CO, NO, NOx) with dilution in pure air in the range 5 ppm to 5 vol% was investigated and studied as a function of the preparation technique. The dense ceramic and the thick film designs behave similarly. A sensor prototype based on the thick film design was then developed and tested. All the experimental results prove that the sensor can be successfully used for selective detection of CO and NOx. The selectivity results from an appropriate choice of the working temperature of the sensing element. At low temperatures (300 to 400°C) NO2 can be selectively detected in the presence of CO; the opposite happens in the higher temperature range (550 to 650°C). 相似文献
9.
Abstract Pyroelectric infrared detectors based on La-modified PbTiO3 (PLT) thin films have been fabricated by RF magnetron sputtering and micromachining technology. The detectors form PB1?xLaxTi1?x/4O3 (x = 0.05) thin film ferroelectric capacitors epitaxially grown in-situ by RF magnetron sputtering on Pt/ MgO(100) substrate. The sputtered PLT thin film exhibits highly c-axis oriented crystal structure (90%) that poling treatment for sensing applications is not required. The c-axis orientation ratio a of deposited PLT thin film strongly depends on the morphology of Pt layer, which in turn varies with the thickness of Pt layer on MgO substrate. We have successfully grown highly c-axis oriented PLT film on Pt electrode with a conductive percolating network structure. Micromachining technology is used to lower the thermal mass of the detector by coating Polyimide on top of the sensing elements to support the fragile structure and by selectively etching the backside of the MgO substrate to reduce the heat loss. The sensing element exhibited a low noise equivalent power (NEP) of 1.7 × 10?10 W and a very high detectivity D? value of 8.5 × 108 cmVHz/W at room temperature. The high performance for pyroelectric infrared sensing is primarily due to the highly c-axis oriented PLT thin film and its minimized thermal mass. 相似文献
10.
AbstractThe design of reduced graphene oxide (RGO) with novel porous structure has attracted tremendous attention owing to their larger specific surface area. Herein, three-dimensional open microcells, bowl-shaped RGO were fabricated through spray drying method which employed polystyrene spheres as a sacrificial template. The bowl-shaped, open microcell-liked pores observed in the RGO network had an average diameter of ≈1?μm. Subsequently, the catalytic SnO2 nanoparticles were loaded on RGO network via a simple solvothermal method (SnO2@RGO), and their gas sensing properties were investigated at room temperature (RT). In a comparison with pristine RGO network, the SnO2@RGO composite exhibited almost 4 times higher response to 400?ppm NO2 at RT and rapid recovery time. The extraordinary sensing performance can be attributed to the novel open microcell-liked porous microstructure with the SnO2 catalyst nanoparticles. 相似文献
11.
Chih-Ming Wang Chih-Yu Wen Ying-Chung Chen Kuo-Sheng Kao Da-Long Cheng Chin-Hao Peng 《Integrated ferroelectrics》2014,158(1):62-68
Tungsten oxide (WO3) thin films were deposited on ITO/glass substrates using the electron beam evaporation technique. The WO3 films were grown on substrates at temperatures varying from room temperature (RT) to 240 °C. The structural characterization and surface morphology were examined using X-ray diffraction (XRD) and a field emission scanning electron microscope (FE-SEM). The electrochromic properties of WO3 thin films were investigated using cyclic voltammograms (CVs) and in situ transmittance measurements, which were performed on WO3 thin films immersed in an electrolyte of 1 M LiClO4 in propylene carbonate (PC). An amorphous 510-nm-thick WO3 film heated at RT exhibits the maximum transmittance variation (ΔT%) of 61.8% between the bleached state and the colored state, with a ΔOD of 0.739, Q of 17.31 mC/cm2 and η of 42.69 cm2/C at a wavelength (λ) of 550 nm. 相似文献
12.
The nanoparticles electrophoretic deposition (EPD) of barium titanate (BaTiO3 or BTO) thin films was investigated. BTO nanocrystallites in a pseudocubic perovskite phase with an average particle size of about 10 nm were synthesized at a low temperature of 90°C by a high-concentration sol–gel process. By using a mixed solvent of 2-methoxyethanol and acetylacetone as dispersing medium, transparent and well-dispersed BTO nanocrystallites suspensions within the concentration range of 0.0125 to 0.20 mol/l was successfully prepared for nanoparticles EPD. A uniform microstructure and a smooth surface were observed on the deposited films. The film thickness of the deposited films increased rapidly with increasing EPD time in the initial period of EPD, and thereafter gradually increased to a limited thickness. With increasing applied EPD voltage, the limited film thickness increased. A near linear relation between the film thickness of films and the concentration of suspensions was observed under the same EPD conditions. The microstructures of the deposited BTO thin films were investigated. 相似文献
13.
Tatsumi Ishihara Toshiaki Takagi Masami Ito Hiroyasu Nishiguchi Yusaku Takita 《Journal of Electroceramics》1999,4(1):207-214
Preparation of CuO-BaTiO3 mixed oxide thin film by the decomposition of a self-assembled multibilayer film as a molecular template was investigated in this study. Furthermore, CO2 sensing property of the resultant thin film was investigated as a capacitive type sensor. The self-assembled bilayer film of few 1000 layers thickness can be obtained easily by casting an aqueous suspension consisting of dimethyldihexadecylammoiun bromide (DC1-16), Cu(ClO4)2, Ba(TiO(C2H4)2), 2,6-dimetyle-3,5heptadione (DHP), and polyvinyl alcohol. Divalent copper ion (Cu2+)) which is associated with 2 DHP molecules was incorporated into the molecular bilayer film and BaTiO3 precursor exists at the interspace of molecular bilayer film by coordinating with polyvinyl alcohol. Upquenching the organic-inorganic film at 1173 K leads to the uniform film of CuO-BaTiO3 oxide mixture. Although operating temperature shifted to higher temperature, the resultant film exhibits the capacitance change upon exposure to CO2. Consequently, it is concluded that the mixed oxide film of CuO-BaTiO3 prepared by the decomposition of multibilayer film was also an appropriate capacitive type CO2 sensor. 相似文献
14.
Tatsumi Ishihara Toshiaki Takagi Masami Ito Hiroyasu Nishiguchi Yusaku Takita 《Journal of Electroceramics》2000,4(1):207-214
Preparation of CuO-BaTiO3 mixed oxide thin film by the decomposition of a self-assembled multibilayer film as a molecular template was investigated in this study. Furthermore, CO2 sensing property of the resultant thin film was investigated as a capacitive type sensor. The self-assembled bilayer film of few 1000 layers thickness can be obtained easily by casting an aqueous suspension consisting of dimethyldihexadecylammoiun bromide (DC1-16), Cu(ClO4)2, Ba(TiO(C2H4)2), 2,6-dimetyle-3,5heptadione (DHP), and polyvinyl alcohol. Divalent copper ion (Cu2+)) which is associated with 2 DHP molecules was incorporated into the molecular bilayer film and BaTiO3 precursor exists at the interspace of molecular bilayer film by coordinating with polyvinyl alcohol. Upquenching the organic-inorganic film at 1173 K leads to the uniform film of CuO-BaTiO3 oxide mixture. Although operating temperature shifted to higher temperature, the resultant film exhibits the capacitance change upon exposure to CO2. Consequently, it is concluded that the mixed oxide film of CuO-BaTiO3 prepared by the decomposition of multibilayer film was also an appropriate capacitive type CO2 sensor. 相似文献
15.
Abstract Pb(Zrx,Ti1?x)O3 thin films were deposited on Pt/SiO2/Si substrates by the rf magnetron sputtering using an alloy target consisting of Zr-Ti alloy and Pb metal. The dependence of electrical properties on film thickness and sputtering gas pressure was investigated. The dielectric constant and the remanent polarization decreased and the coercive field increased with the decrease of the film thickness. In the dependence of gas pressure, the relative dielectric constant of the film with only a perovskite phase were in the range of 235–280, which were higher than those of the film with only a pyrochlore phase, 20. The asymmetry of hysteresis loops increased with the decrease of the gas pressure. 相似文献
16.
This paper describes the characteristics of chemiresistor hydrogen (H2) sensors with different ZnO film structures in which ZnO dense films, nanoparticles (NPs), and nanorods (NRs) were prepared by RF magnetron sputtering, the sol–gel method, and the hydrothermal method, respectively. These were decorated with a Pt NP catalyst to investigate the performance of devices comprised of these structures. The effects of the ZnO morphology and operating temperature on the gas sensing behavior of the sensor are reported in detail. The various ZnO film morphologies, which contributed significantly to differences between sensors, play a very important role in enhancement of the supported Pt catalyst area and initial oxygen absorption on the ZnO surface. ZnO dense films prepared by sputtering showed the fastest response with a 13.5 % resistance variation at 1,000 ppm H2 because gas adsorption occurred only on the film surface. The sensor with ZnO NRs showed a slower response, but the highest change in resistance of 65.5 % occurred at 1,000 ppm H2 at room temperature. H2 sensing performance of the chemiresistor sensors was improved due to the Pt catalyst, which was more efficient in dissociating H2 gas molecules even at low temperature. The best chemiresistor sensor was fabricated using ZnO NRs and had a response time of approximately 10 s, a 27 s recovery time, and an 81.5 % change in resistance at 200 °C. 相似文献
17.
Ricardo Rangel Lidia Chávez-Chávez Manuel García-Méndez Eduardo Martínez 《Journal of Electroceramics》2012,28(1):34-44
CeO2, Ce(1-x)MXO2, {M = Ru, In} compounds with sensing properties were fabricated using the sol–gel route. The main purpose was to compare
the efficiency of CeO2 vs. Ce(1-x)MXO2 doped compounds as gas sensors for NO2 detection. Characterization was performed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface
area determination (BET). Measurements of electrical resistance under different conditions of time, concentration and temperature
in the presence of NO2 were carried out. Ruthenium inclusion increased the CeO2 sensor response in a great extent, gas response (S) = 1.8 for CeO2 vs. gas response (S) = 350 for Ce0.95Ru0.05O2 and gas response (S) = 35 for Ce0.95In0.05O2. This behavior is reported by the first time. Our results demonstrate that ruthenium or indium inclusion has been beneficial
for CeO2. Conclusively the materials herein described could be applied as NO2 gas sensors. 相似文献
18.
Z. Surowiak D. Czekaj A. A. Bakirov E. V. Sviridov V. P. Dudkevich 《Integrated ferroelectrics》2013,141(4):267-282
Abstract By means of r.f. sputtering of the ceramic targets or pressed powder targets with the chemical constitution of Pb (Zr0.52Ti0.46W0.01Cd0.01) O3 the polycrystalline thin ferroelectric films with the perovskite type structure and of thickness df = (1–2, 5) × 10?6 m on metal (stainless steel, platinum) or ceramic (polycor) substrates have been obtained. In case of thin film deposition on steel substrate and on platinum at low temperatures (Tx < 723 K) the nonferroelectric intermediate layer with the same chemical constitution but with the pyrochlore type structure have been created. Results of the X-ray analysis and dielectric investigations (low frequency dispersion) have proved existence of such a structure. The structural phase transition (P4mm ? Pm3m) takes place in the thin ferroelectric films. This is a diffuse type transition and the degree of diffuseness depends on the structural perfection of the thin films. The measure of the structural perfection of the thin films was taken to be the mean value of the lattice strains (microdeformations) ? Δd/d ? where “d”-interplane distance and the mean dimension (D) of the areas of coherent X-rays scattering (crystallites). With increase in ? Δd/d ? and decrease in D the degree of diffuseness increases. For quantitative and qualitative describing of this dependence in thin PZT films the phenomenological model of diffused phase transition developed earlier by the authors for thin BaTiO3 films has been applied. In this case a good agreement between theory and experiment have been achieved for low values of ? Δd/d ?. 相似文献
19.
Ho-Gi Kim 《Integrated ferroelectrics》2013,141(4):371-381
Abstract Lead titanate (PbTiO3) thin films have been prepared on titanium dioxide coated silicon wafers by chemical vapor deposition (CVD). The pure PbTiO3 thin films were deposited by controlling the experimental conditions. The gas phase reaction of TiO2 occurred by exceeding the critical value of titanium input fraction at constant oxygen partial pressure. Strontium titanate (SrTiO3) thin films have been prepared on p-type silicon wafers by radio frequency (RF) magnetron sputtering. The SrTiO3 thin film was polycrystalline and the Sr/Ti ratio of this film was 0.91. The SrTiO3 thin films contain three regions, an external surface layer, a main layer and an interfacial layer. The stoichiometric SrTiO3 thin film was obtained by using the SrO excess target. The SrTiO3 film annealed at 600[ddot]C has an ideal capacitance-voltage (C-V) curve and maximum effective dielectric constant. 相似文献
20.
H. Buhay S. Sinharoy M. H. Francombe W. H. Kasner J. Talvacchio B. K. Park 《Integrated ferroelectrics》2013,141(2-4):213-222
Abstract In this paper we describe recent successes of growth of epitaxial bismuth titanate (BTO) films by pulsed laser deposition (PLD) suitable for electro-optic and electrical switching device structures, and fabrication of an improved gate structure for a ferroelectric memory FET (FEMFET). TEM and x-ray results indicate that excellent crystalline quality BTO films were achieved on LaAlO3. Polarization switching was demonstrated for BTO capacitors with epitaxial superconducting YBa2Cu3O7 as the lower electrode. Using an SiO2 buffer layer, a BTO/Si structure was fabricated and direct charge modulation in the Si by polarization reversal in the BTO was demonstrated. 相似文献