In the paper, the authors analyse the rela- tionship between the electrical conductivity σ of ZrO_2 and the content of doped stabilizing agent by the Positron Annihilation Technique, and explain the change tendency ...In the paper, the authors analyse the rela- tionship between the electrical conductivity σ of ZrO_2 and the content of doped stabilizing agent by the Positron Annihilation Technique, and explain the change tendency of σ with the content of stabilizing agent. The research shows that 'number of effective vacancy' in material is a decisive factor causing change of σ.展开更多
The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2 (9mol% Y2O3) slurry and then co-fir...The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2 (9mol% Y2O3) slurry and then co-firing at 1750°C for 8 h. The double-cell method was employed to measure the electronic conductivity parameter and exam the reproducibility of the coated Mg- PSZ tube. The experimental results indicate that the good thermal shock resistance of the Mg-PSZ tube can be retained when the coating thickness is not more than 3.4 μm. The ZrO2 (9mol% Y2O3) coating reduces the electronic conductivity parameter remarka- bly, probably due to the lower electronic conductivity of Y2O,-stabilized ZrO2 than that of MgO-stabilized ZrO2. Moreover, the ZrO2 (9mol% Y2O3) coating can improve the reproducibility and accuracy of the Mg-PSZ tube significantly in the low oxygen measure- ment. The smooth surface feature and lower electronic conductivity of the coated Mg-PSZ tube should be responsible for this im- provement.展开更多
The thermal equilibrium state of the reference electrode was investigated. The results show that the temperature difference between the inside and the outside of zirconia tube was very small and the Seebeck effect can...The thermal equilibrium state of the reference electrode was investigated. The results show that the temperature difference between the inside and the outside of zirconia tube was very small and the Seebeck effect can be ignored after the sensor was dipped into liquid steel for more than 2 s. A special sensor was designed to test the relation between the EMF （electromotive force） of sensor and the thermal equilibrium state of the reference elec- trode. Based on these results, it is suggested that the peak in EMF curve was caused by the change of oxygen potential in reference electrode before the thermal equilibrium was reached. If NiO was added by 2 M- 5 M to the Cr/Cr2O3 reference electrode, the peak in EMF curve could be eliminated.展开更多
A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-l...A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.展开更多
An extended-life and ultra-low oxygen sensor has been fabricated by using polycrystalline Caβ″/β/α-Al2O3 as a solid electrolyte. Five reference electrodes CaO+O2, Caβ″/β/α-Al2O3 (powder)+O2,Cr+Cr2O3, Nb+NbO an...An extended-life and ultra-low oxygen sensor has been fabricated by using polycrystalline Caβ″/β/α-Al2O3 as a solid electrolyte. Five reference electrodes CaO+O2, Caβ″/β/α-Al2O3 (powder)+O2,Cr+Cr2O3, Nb+NbO and Mo+MoO2 were tested in order to select a better reference electrode for this sensor. The limit of determining oxygen activity and the extended-life of the sensor were also tested in this study.展开更多
A fiber optic 2-cholrophenol（2-CP） sensor was developed based on the fluorescence quenching of molecular oxygen on the oxygen-sensitive membrane and O2 consumption during catalytic oxidation reaction of 2-CP. The 2-...A fiber optic 2-cholrophenol（2-CP） sensor was developed based on the fluorescence quenching of molecular oxygen on the oxygen-sensitive membrane and O2 consumption during catalytic oxidation reaction of 2-CP. The 2-CP concentration can be determined by utilizing a lock-in amplifier to measure the change in the fluorescence lifetime of an oxygen-sensitive membrane, in which the tris（2,2′-bipyridyl） ruthenium（II） chloride complexes（Ru（II）（byp）3Cl2） were immobilized in cellulose acetate（CA） via simple hybridized approach. The experimental results show the good linear relationship between the phase delay of sensitive membrane and 2-CP concentration in its detection range of 1×10-7 to 1×10-5 mol/L and 1×10-5 to 1×10-4 mol/L. The detection limit of the sensor is 7×10-8 mol/L（S/N=3） and the response time is 5 min. Our experimental measurements confirmed good response characteristics of the as-prepared fiber optic 2-CP sensor, as well as its capability to detect the 2-CP concentration in practical water samples.展开更多
The high sensitivity of room-temperature gas sensors is the key to innovation in the areas of environment,energy conservation and safety.However,metal-oxide-based sensors generally operate at high temperatures.Herein,...The high sensitivity of room-temperature gas sensors is the key to innovation in the areas of environment,energy conservation and safety.However,metal-oxide-based sensors generally operate at high temperatures.Herein,we designed three ZrO_(2)-based sensors and explored their NO_(2)sensing properties at room temperature.ZrO_(2)with three different morphologies and microstructure were synthesized by simple hydrothermal methods.The microstructures of sensing materials are expected to significantly affect gas sensing properties.The rod-shaped ZrO_(2)(ZrO_(2)-R)displayed the advantages such as higher crystallinity,larger pore size,narrower band gap and more chemisorbed adsorbed oxygen,compared to hollow sphere-shaped ZrO_(2)(ZrO_(2)-HS),stellate-shaped ZrO_(2)(ZrO_(2)–S).The ZrO_(2)-R sensor showed the highest response towards 30 ppm NO_(2)(423.8%)at room temperature,and a quite high sensitivity of 198.0%for detecting 5 ppm NO_(2).Although ZrO_(2)-HS and ZrO_(2)–S sensors exhibited lower response towards 30 ppm NO_(2)(232.9%and 245.1%),the response time and recovery time of these two sensors are 5 s/19 s and 4 s/3 s,respectively.This work can provide a new strategy for the development of roomtemperature metal-oxide-based sensors.展开更多
（Bi2O3）0.73（Y2O3）0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen ch...（Bi2O3）0.73（Y2O3）0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 （Y2O3 stabilized） oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10^-2-1×10^-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10^-37-1×10^-27 Pa at 1.0 V and 1×10^-53-1×10^47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.展开更多
The selectivity of gas sensing materials is increasingly important for their applications. The oxygenregulated SnO2 films with(110) and(101) preferred orientation were obtained through magnetron sputtering, followed b...The selectivity of gas sensing materials is increasingly important for their applications. The oxygenregulated SnO2 films with(110) and(101) preferred orientation were obtained through magnetron sputtering, followed by annealing treatment. Their micro-structure, surface morphology and gas response were investigated by advanced structural characterization and property measurement. The results showed that the as-prepared(110)-oriented SnO2 film was oxygen-rich and had more adsorption sites while the as-prepared(101)-oriented SnO2 film was oxygen-poor and more sensitive to de-oxidation.H2 gas sensitivity, response speed, selectivity between H2 and CO of the(110)-orientated SnO2 film was superior to that of the(101)-orientated SnO2 film. After treated at high temperature and high vacuum,the reduction of gas-sensing properties of the annealed(110) SnO2 film was much more than that of the annealed(101) SnO2 film. The lattice oxygen was responsible for the difference in gas-sensing response between(110) and(101)-oriented SnO2 films under oxygen regulation. This work indicated the gassensing selectivity of the different crystal planes in SnO2 film, providing a significant reference for design and extension of the related materials.展开更多
文摘In the paper, the authors analyse the rela- tionship between the electrical conductivity σ of ZrO_2 and the content of doped stabilizing agent by the Positron Annihilation Technique, and explain the change tendency of σ with the content of stabilizing agent. The research shows that 'number of effective vacancy' in material is a decisive factor causing change of σ.
文摘The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2 (9mol% Y2O3) slurry and then co-firing at 1750°C for 8 h. The double-cell method was employed to measure the electronic conductivity parameter and exam the reproducibility of the coated Mg- PSZ tube. The experimental results indicate that the good thermal shock resistance of the Mg-PSZ tube can be retained when the coating thickness is not more than 3.4 μm. The ZrO2 (9mol% Y2O3) coating reduces the electronic conductivity parameter remarka- bly, probably due to the lower electronic conductivity of Y2O,-stabilized ZrO2 than that of MgO-stabilized ZrO2. Moreover, the ZrO2 (9mol% Y2O3) coating can improve the reproducibility and accuracy of the Mg-PSZ tube significantly in the low oxygen measure- ment. The smooth surface feature and lower electronic conductivity of the coated Mg-PSZ tube should be responsible for this im- provement.
文摘The thermal equilibrium state of the reference electrode was investigated. The results show that the temperature difference between the inside and the outside of zirconia tube was very small and the Seebeck effect can be ignored after the sensor was dipped into liquid steel for more than 2 s. A special sensor was designed to test the relation between the EMF （electromotive force） of sensor and the thermal equilibrium state of the reference elec- trode. Based on these results, it is suggested that the peak in EMF curve was caused by the change of oxygen potential in reference electrode before the thermal equilibrium was reached. If NiO was added by 2 M- 5 M to the Cr/Cr2O3 reference electrode, the peak in EMF curve could be eliminated.
基金supported by National Natural Science Foundation of China under grant No.59374160.
文摘A novel electrochemical oxygen sensor has been developed by using La beta -Al2O3 as solid electrolyte and Cr+Cr2O3 as reference electrode. The sensor not only can be used as normal oxygen sensor but also as an ultra-low oxygen sensor. Especially, it is very sensitive to measure ultra-low oxygen in molten metal. For estimating the accuracy of La beta -Al2O3 oxygen sensor, two series of oxygen activities in molten iron at different oxygen contents and different temperature were measured by both La beta -Al2O3 oxygen sensor and ZrO2 oxygen sensor. The theoretical values of oxygen activities in molten iron (3.30%C, in mass fraction) at 1723K and 1745K were also evaluated for comparing the measuring results of two sensors. At last, the error of measurement for La beta -Al2O3 oxygen sensor was discussed too.
文摘An extended-life and ultra-low oxygen sensor has been fabricated by using polycrystalline Caβ″/β/α-Al2O3 as a solid electrolyte. Five reference electrodes CaO+O2, Caβ″/β/α-Al2O3 (powder)+O2,Cr+Cr2O3, Nb+NbO and Mo+MoO2 were tested in order to select a better reference electrode for this sensor. The limit of determining oxygen activity and the extended-life of the sensor were also tested in this study.
基金Funded by the National Natural Science Foundation of China(No.61377092)
文摘A fiber optic 2-cholrophenol（2-CP） sensor was developed based on the fluorescence quenching of molecular oxygen on the oxygen-sensitive membrane and O2 consumption during catalytic oxidation reaction of 2-CP. The 2-CP concentration can be determined by utilizing a lock-in amplifier to measure the change in the fluorescence lifetime of an oxygen-sensitive membrane, in which the tris（2,2′-bipyridyl） ruthenium（II） chloride complexes（Ru（II）（byp）3Cl2） were immobilized in cellulose acetate（CA） via simple hybridized approach. The experimental results show the good linear relationship between the phase delay of sensitive membrane and 2-CP concentration in its detection range of 1×10-7 to 1×10-5 mol/L and 1×10-5 to 1×10-4 mol/L. The detection limit of the sensor is 7×10-8 mol/L（S/N=3） and the response time is 5 min. Our experimental measurements confirmed good response characteristics of the as-prepared fiber optic 2-CP sensor, as well as its capability to detect the 2-CP concentration in practical water samples.
基金supported by the Natural Science Foundation of Hebei Province(Project No.F2020202050)the National Natural Science Foundation of China(Grant No.62004059,11632004 and U1864208)+5 种基金the Key Program for International Science and Technology Cooperation Projects of the Ministry of Science and Technology of China(No.2016YFE0125900)National Science and Technology Major Project(2017-VII-0011-0106)Science and Technology Planning Project of Tianjin(20ZYJDJC00030)the Key Program of Research and Development of Hebei Province(202030507040009)the Fund for Innovative Research Groups of Natural Science Foundation of Hebei Province(A2020202002)the Key Project of Natural Science Foundation of Tianjin(S20ZDF077).
文摘The high sensitivity of room-temperature gas sensors is the key to innovation in the areas of environment,energy conservation and safety.However,metal-oxide-based sensors generally operate at high temperatures.Herein,we designed three ZrO_(2)-based sensors and explored their NO_(2)sensing properties at room temperature.ZrO_(2)with three different morphologies and microstructure were synthesized by simple hydrothermal methods.The microstructures of sensing materials are expected to significantly affect gas sensing properties.The rod-shaped ZrO_(2)(ZrO_(2)-R)displayed the advantages such as higher crystallinity,larger pore size,narrower band gap and more chemisorbed adsorbed oxygen,compared to hollow sphere-shaped ZrO_(2)(ZrO_(2)-HS),stellate-shaped ZrO_(2)(ZrO_(2)–S).The ZrO_(2)-R sensor showed the highest response towards 30 ppm NO_(2)(423.8%)at room temperature,and a quite high sensitivity of 198.0%for detecting 5 ppm NO_(2).Although ZrO_(2)-HS and ZrO_(2)–S sensors exhibited lower response towards 30 ppm NO_(2)(232.9%and 245.1%),the response time and recovery time of these two sensors are 5 s/19 s and 4 s/3 s,respectively.This work can provide a new strategy for the development of roomtemperature metal-oxide-based sensors.
基金the National Natural Science Foundation of China (50774018)
文摘（Bi2O3）0.73（Y2O3）0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 （Y2O3 stabilized） oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10^-2-1×10^-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10^-37-1×10^-27 Pa at 1.0 V and 1×10^-53-1×10^47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.
基金financially supported by the National Natural Science Foundation of China (Nos. 51502126 and 51874169)the Natural Science Foundation of Liaoning Province (No. 20180550802)
文摘The selectivity of gas sensing materials is increasingly important for their applications. The oxygenregulated SnO2 films with(110) and(101) preferred orientation were obtained through magnetron sputtering, followed by annealing treatment. Their micro-structure, surface morphology and gas response were investigated by advanced structural characterization and property measurement. The results showed that the as-prepared(110)-oriented SnO2 film was oxygen-rich and had more adsorption sites while the as-prepared(101)-oriented SnO2 film was oxygen-poor and more sensitive to de-oxidation.H2 gas sensitivity, response speed, selectivity between H2 and CO of the(110)-orientated SnO2 film was superior to that of the(101)-orientated SnO2 film. After treated at high temperature and high vacuum,the reduction of gas-sensing properties of the annealed(110) SnO2 film was much more than that of the annealed(101) SnO2 film. The lattice oxygen was responsible for the difference in gas-sensing response between(110) and(101)-oriented SnO2 films under oxygen regulation. This work indicated the gassensing selectivity of the different crystal planes in SnO2 film, providing a significant reference for design and extension of the related materials.
