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Development Of Ceramic Li Electrolyte Based Co2 Sensors For Temperatures Ranging From Ambient To High Temperature
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Book Synopsis Development of Ceramic Li-electrolyte Based CO2 Sensors for Temperatures Ranging from Ambient to High Temperature by : Inhee Lee
Download or read book Development of Ceramic Li-electrolyte Based CO2 Sensors for Temperatures Ranging from Ambient to High Temperature written by Inhee Lee and published by . This book was released on 2009 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Solid-state electrochemical CO2 gas sensors composed of an electrolyte and two porous electrodes have been used extensively in the automobile and bio-chemical industry. Based on the field of application, the working temperature of the sensor ranges from room temperature to 600 °C. Two potentiometric CO2 sensors that work at different temperature ranges were developed in this work. A potentiometric CO2 gas sensor with Li3PO4 electrolyte and BaCO3coated Li2CO3sensing electrode was developed and the sensing electrode was characterized in order to understand its sensing mechanism under humid conditions. This potentiometric CO2 sensor showed humidity-interference-free sensing response for high CO2 concentrations (5~25%) at high temperatures (T> 400 °C). In addition, the sensor showed good reproducibility and long-term stability under humid conditions. In the sensing electrode, the BaCO3layer improved the resistance against humidity as a chemical barrier, while the inner Li2CO3layer was responsible for the CO2 sensing. However, the sensor in which the eutectic layer covered the entire sensing electrode showed good sensing behavior under dry and humid conditions. Lately, low-temperature CO2 sensors have been attracting attention due to their low power consumption and easy sensor miniaturization, since a heater is unnecessary. We have developed a low-temperature CO2 sensor based on lithium lanthanum titanate (LLT) electrolyte in dry conditions that requires further improvement. Lithium lanthanum titanate (LLT) electrolytes were prepared by a conventional solid-state method. The impedance of the LLT electrolyte was measured over the temperature range of 300 to 473 K and the frequency range of 5 Hz and 13 MHz. Activation energies for the Li ionic conduction for grain boundary and grain were estimated to be 0.47 and 0.31 eV, respectively. It was found that LLT is a good ionic conductor at low temperatures and a good candidate as an electrolyte for low-temperature electrochemical cells. A La2/3-xLixTiO3LLT)-based CO2 sensor with a mixture of CeO2, Au, and Li2CO3as the sensing electrode has been developed and shown to have relatively stable sensing behaviors at 200 °C under dry conditions. However, this sensor showed non-Nernstian behavior because electrochemical reactions were not fast enough on the sensing electrode and the solid electrolyte may have some electronic conduction. In addition, the observed sensitivity was less than the theoretical prediction. By adding K2CO3on the sensing electrode, the sensitivity of the low-temperature CO2 sensor was slightly improved. However, the sensing signals of the sensors were degraded by water vapor under humid conditions due to the formation of KHCO3or K2CO3mH2O (m= 2, 3, or 6). To optimize the low-temperature CO2 sensor, a more active sensing electrode is needed, which may be achieved by controlling the size of particles and their distribution on the electrode. In addition, a thinner electrolyte with pure ionic conduction is also required.
Book Synopsis Development and Characterization of Ceramic-Based Carbon Monoxide Sensors by : Lora Birkefeld Younkman
Download or read book Development and Characterization of Ceramic-Based Carbon Monoxide Sensors written by Lora Birkefeld Younkman and published by . This book was released on 1995 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In recent years, the importance of monitoring combustion processes for fuel efficiency and pollution control has necessitated the development of reliable gas sensors for high temperature in situ detection. Semiconductor gas sensors have been developed for a wide range of reactive gases, but are typically nonselective to any particular gas in gaseous mixtures. The objective of this research was to develop fast-responding solid-state sensors for the selective detection of CO gas at elevated temperatures, as well as to understand and characterize the associated sensing mechanisms. From preliminary dc electrical resistance measurements, the sensing properties of various semiconducting oxides were investigated, and Mo03- and Ti02-based systems were selected as candidate sensor materials. Mo03 was found to display an ON/OFF-type sensing behavior. X-ray photoelectron spectroscopy (XPS) results indicated that the sensitivity could be attributed to the surface reduction of Mo03 to the Mo02 phase. The Ti02 sensor displayed a gradual drop in electrical resistance with increasing CO concentration but suffered from H2 interference. Two different mechanisms were proposed (based on recovery characteristics) to describe the sensitivity of Ti02: a surface-controlled mechanism for CO, supported by XPS data, and a bulk-diffusion controlled mechanism for H2. Through second phase additions of 10 wt% Y203 and 10 wt% Al203, the sensor was made selective to CO and H2, respectively with no interference from NOx. Fe and Pd catalyst additions improved both the response time and the lower limit of CO detection. A sensor device of (Ti02-10 wt% Y203)-5 wt% Pd was developed with optimized geometry, electrode configuration, and processing conditions. A prototype device was sucessfully tested in an automobile engine for over 50 cycles, responding quickly and reversibly under revving and idling conditions. Immittance spectroscopy (IS) was employed to characterize the electrical behavior of Ti02. By extracting the electrical parameters through lumped parameter/complex plane analysis, the sensing behavior was found to be grain boundary-controlled, with sensitivity determined by electrical barriers at the intergranular contacts. Upon exposure to CO gas, these barriers are effectively lowered, and the depletion region width decreases. The observed decrease in electrical resistance and increase in grain boundary capacitance provided evidence in support of this proposed mechanism.
Download or read book JJAP written by and published by . This book was released on 2000 with total page 1060 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book JJAP Letters written by and published by . This book was released on 2000 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Study of Interface Reaction of Li0.35La0.55TiO3-Li2CO3 and Its Effect on Potentiometric CO2 Gas Sensors by : Junro Yoon
Download or read book A Study of Interface Reaction of Li0.35La0.55TiO3-Li2CO3 and Its Effect on Potentiometric CO2 Gas Sensors written by Junro Yoon and published by . This book was released on 2012 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A new potentiometric CO2 gas sensor using lithium-lanthanum-titanate (Li0.35La0.55TiO3) electrolyte, Li2CO3 sensing electrode, and Li2TiO3+TiO2 reference electrode was investigated. The microstructure and electrical properties of the optimized solid electrolyte were examined and the measured conductivity values were found consistent with those reported in literature. The sensor was tested under dry condition in 21% O2/N2 at temperatures ranging from 250 to 550°C. As the temperature increased, the percentage of Nernstian behavior improved from 50% at 250°C to 95% at 450°C, but the performance degraded above 450°C. The proposed hypothesis for the degradation is as follows. Depending on CO2 partial pressure, Li2CO3 can decompose and react with Li0.35La0.55TiO3 around 475-500°C resulting in insertion of Li+ into Li0.35La0.55TiO3 that causes structural distortion. When the reaction between Li2CO3 and Li0.35La0.55TiO3 occurs at elevated temperatures such as at 700°C, the distorted structure transforms to disordered LaLi1/3Ti2/3O3 and the sensor performance degrades irreversibly. Thermodynamic calculations combined with solid-state reaction under controlled atmosphere followed by X-ray diffraction (XRD) are used to confirm the hypothesis. Finally, for device fabrication, it is demonstrated that introduction of high concentration of CO2 (~99.99%) can avoid the reaction between Li2CO3 and Li0.35La0.55TiO3 at high temperatures, which also facilitates good bonding between the electrode and the electrolyte. As for long-term device performance, it is shown that the sensor can measure changes in CO2 concentrations reproducibly as long as it is operated in conditions where there is a background of CO2, such as in ambient atmosphere or combustion systems.
Download or read book Ceramic Abstracts written by and published by . This book was released on 2000 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Novel Strategies for Design of High Temperature Titania-based Gas Sensors for Combustion Process Monitoring by : Marla Lea Frank
Download or read book Novel Strategies for Design of High Temperature Titania-based Gas Sensors for Combustion Process Monitoring written by Marla Lea Frank and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: TiO2 -based sensors were developed and characterized for improvement of selectivity and sensitivity towards CO gas at high temperatures. Selectivity was improved by combining several sensors into an array, while sensitivity improvement was studied by examination of the effects of various metal and metal oxide additives and reactive sputtering film preparation. TiO2-based sensors containing La2O3 and La2O3/CuO were combined into an array for testing of CO and O2 gas mixtures. Nonlinear regression analysis was developed to determine the concentrations of gases in the mixture. The regression technique can be used to determine the prediction ability of gas sensor combinations for given gas concentration ranges using a defined orthogonality index, as well as to determine the amount of each gas in the mixture based on the responses of a set of sensors. The prediction ability for a La2O3-containing sensor combined with La2O3/CuO-containing sensors with varying levels of CuO are compared for a range of CO and O2 concentrations. Concentrations of CO and O2 in gas mixtures are predicted using the La2O3- and La2O3/CuO-containing sensors and the regression analysis. Addition of various metals and metal oxides, including Au, CuO and La2O3 to TiO2-based gas sensors has been examined to determine the effect of additives on the gas-surface reactivity and electrical response of the sensors. Electrical measurements show that sensor sensitivity is decreased upon addition of La2O3 with only a slight increase in sensitivity when CuO is added to La2O3-containing sensors. Au, however, was found to increase the sensitivity of the TiO2-based sensors with and without La2O3. Gas chromatography was used to determine the catalytic conversion of CO for the various sensor materials at different temperatures for comparison with electrical measurements. General guidelines for additive selection have been proposed based on the results. Reactively sputtered thin film TiO2 gas sensors have been fabricated and characterized for improved sensitivity to CO gas. Sensitivity of optimized thin film sensors to CO was found to be much higher than for traditional thick film TiO2-based sensors. Characterization of the phase and morphology of the sensors using XRD, TEM and AFM show that the film consists of a dense layer of TiO2 in the rutile phase, with surface roughness changing with film thickness. Sensitivity of the thin film sensor could be varied by changing the film thickness, with a film thickness of 240 nm showing the best sensitivity to CO gas, although response and recovery times were slow.
Book Synopsis Progress in Solid Oxide Fuel Cells by : American Ceramic Society
Download or read book Progress in Solid Oxide Fuel Cells written by American Ceramic Society and published by Wiley-American Ceramic Society. This book was released on 2006-06-30 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work provides a collection of current research papers including valuable insights on materials-related aspects of solid-oxide fuel cells current status, processing and fabrication, various electrolytes, anodes, and cathodes, ceramic/metal interconnects, seal materials, mechanical properties, characterization, modeling, fuel reforming, component materials, materials processing, performance, stability, and more.
Download or read book Science Abstracts written by and published by . This book was released on 1995 with total page 1990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydrogen, Batteries and Fuel Cells by : Bengt Sundén
Download or read book Hydrogen, Batteries and Fuel Cells written by Bengt Sundén and published by Academic Press. This book was released on 2019-07-02 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen, Batteries and Fuel Cells provides the science necessary to understand these important areas, considering theory and practice, practical problem-solving, descriptions of bottlenecks, and future energy system applications. The title covers hydrogen as an energy carrier, including its production and storage; the application and analysis of electrochemical devices, such as batteries, fuel cells and electrolyzers; and the modeling and thermal management of momentum, heat, mass and charge transport phenomena. This book offers fundamental and integrated coverage on these topics that is critical to the development of future energy systems. - Combines coverage of hydrogen, batteries and fuel cells in the context of future energy systems - Provides the fundamental science needed to understand future energy systems in theory and practice - Gives examples of problems and solutions in the use of hydrogen, batteries and fuel cells - Considers basic issues in understanding hydrogen and electrochemical devices - Describes methods for modeling and thermal management in future energy systems
Book Synopsis Ceramic Materials for Energy Applications, Volume 32, Issue 9 by : Yutai Katoh
Download or read book Ceramic Materials for Energy Applications, Volume 32, Issue 9 written by Yutai Katoh and published by John Wiley & Sons. This book was released on 2011-10-11 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a collection of papers from The American Ceramic Society's 35th International Conference on Advanced Ceramics and Composites, held in Daytona Beach, Florida, January 23-28, 2011. This issue includes papers presented in the Ceramics for Electric Energy Generation, Storage and Distribution; Advanced Ceramics and Composites for Nuclear and Fusion Applications; and Advanced Materials and Technologies for Rechargeable Batteries symposia.
Book Synopsis Materials for Energy Conversion Devices by : C C Sorrell
Download or read book Materials for Energy Conversion Devices written by C C Sorrell and published by Elsevier. This book was released on 2005-10-30 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the finite capacity and pollution problems of fossil fuels grow more pressing, new sources of more sustainable energy are being developed. Materials for energy conversion devices summarises the key research on new materials which can be used to generate clean and renewable energy or to help manage problems from existing energy sources.The book discusses the range of materials that can be used to harness and convert solar energy in particular, including the properties of oxide materials and their use in producing hydrogen fuel. It covers thermoelectric materials and devices for power generation, ionic conductors and new types of fuel cell. There are also chapters on the use of such materials in the immobilisation of nuclear waste and as electrochemical gas sensors for emission control.With its distinguished editors and international team of contributors, Materials for energy conversion devices is a standard reference for all those researching and developing a new generation of materials and technologies for our energy need. - Detailed coverage of solar energy and thermoelectric conversion - Comprehensive survey of new developments in this exciting field - Edited by leading experts in the field with contributions from an international team of authors
Book Synopsis Electrical & Electronics Abstracts by :
Download or read book Electrical & Electronics Abstracts written by and published by . This book was released on 1997 with total page 1860 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2726 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1992 with total page 1156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
