Ce-doped nanosized ZnO desulfurizer was prepared by homogeneous precipitation,and its desulfurization efficiency at ambient temperature was investigated through dynamic experiments.The results showed that the desulfur...Ce-doped nanosized ZnO desulfurizer was prepared by homogeneous precipitation,and its desulfurization efficiency at ambient temperature was investigated through dynamic experiments.The results showed that the desulfurization activity of nanosized Ce-ZnO had improved greatly,compared to nanosized ZnO desulfurizer.Nanosized Ce-ZnO desulfurizer was characterized by XRD,TPD-MS,XPS,and TEM.The research results indicated that doping Ce decreased the particle size of the nanosized ZnO desulfurizer and ZnS was the principal desulfurization product.There were adsorption complexes of HS and S on the surface of desulfurizer as well.Only a small amount of vapor appeared in the tail gas on the condition of meeting the precision of desulfurization.展开更多
Cu-Ag-Zr-Ce alloy has an excellent combination of high mechanical strength and high electrical conductivity. By means of a vacuum induction melting, Cu-Ag-Zr-Ce alloy was produced. The effects of aging processes and r...Cu-Ag-Zr-Ce alloy has an excellent combination of high mechanical strength and high electrical conductivity. By means of a vacuum induction melting, Cu-Ag-Zr-Ce alloy was produced. The effects of aging processes and rare earths element cerium on microhardness and conductivity of Cu-Ag-Zr-Ce alloy were studied. By aging at 480 ℃ for 2 h, the alloy has an excellent combination of microhardness and conductivity, the microhardness and conductivity reach 132 HV and 80.24%IACS, respectively. The precipitates responsible for the age-hardening effect are f. c. c. Cu_5Zr, the fine and dispersed precipitates are fully coherent with the Cu matrix, and make the Cu-Ag-Zr-Ce alloy possesses higher hardness and conductivity. With the addition of trace rare earth element cerium, the strength is increased about 9～49 MPa, but the effect on conductivity is very little.展开更多
Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabil...Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...展开更多
Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it m...Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging extent.For comparison,the H-BEA support was aged under the same conditions.Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and acidity.The HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.展开更多
The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed. The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 °C could be completed ...The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed. The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 °C could be completed within 12 h, while this process in the Ce-containing alloy required more time. In subsequent aging process at 175 °C, Ce obviously delayed the aging process of AZ91D. It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution, and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.展开更多
The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temp...The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 oC changed more than four order of magnitude in the relative humidity（RH） range of 11%-95% at 25 oC.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These re-sults indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.展开更多
基金Project supported by the National Natural Science Foundation of China(50478026)
文摘Ce-doped nanosized ZnO desulfurizer was prepared by homogeneous precipitation,and its desulfurization efficiency at ambient temperature was investigated through dynamic experiments.The results showed that the desulfurization activity of nanosized Ce-ZnO had improved greatly,compared to nanosized ZnO desulfurizer.Nanosized Ce-ZnO desulfurizer was characterized by XRD,TPD-MS,XPS,and TEM.The research results indicated that doping Ce decreased the particle size of the nanosized ZnO desulfurizer and ZnS was the principal desulfurization product.There were adsorption complexes of HS and S on the surface of desulfurizer as well.Only a small amount of vapor appeared in the tail gas on the condition of meeting the precision of desulfurization.
文摘Cu-Ag-Zr-Ce alloy has an excellent combination of high mechanical strength and high electrical conductivity. By means of a vacuum induction melting, Cu-Ag-Zr-Ce alloy was produced. The effects of aging processes and rare earths element cerium on microhardness and conductivity of Cu-Ag-Zr-Ce alloy were studied. By aging at 480 ℃ for 2 h, the alloy has an excellent combination of microhardness and conductivity, the microhardness and conductivity reach 132 HV and 80.24%IACS, respectively. The precipitates responsible for the age-hardening effect are f. c. c. Cu_5Zr, the fine and dispersed precipitates are fully coherent with the Cu matrix, and make the Cu-Ag-Zr-Ce alloy possesses higher hardness and conductivity. With the addition of trace rare earth element cerium, the strength is increased about 9～49 MPa, but the effect on conductivity is very little.
基金supported by the National 863 Research Project (2006AA03Z219)Natural Science Foundation of Jiangsu Province (BK2007199)Foundation for "Liu Da Ren Cai" of Jiangsu Province (06-E-021)
文摘Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...
基金supported the National Key R&D Program of China(2021YFB3503200)the Innovative Research Groups of the National Natural Science Foundation of China(51921004)+1 种基金Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)the Key R&D Project of Shandong Province(2021CXGC010703,2022CXGC020311)。
文摘Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging extent.For comparison,the H-BEA support was aged under the same conditions.Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and acidity.The HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.
基金Project supported by the Natural Science Foundation of Inner Mongolia (2009MS0801)
文摘The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed. The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 °C could be completed within 12 h, while this process in the Ce-containing alloy required more time. In subsequent aging process at 175 °C, Ce obviously delayed the aging process of AZ91D. It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution, and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.
文摘The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 oC changed more than four order of magnitude in the relative humidity（RH） range of 11%-95% at 25 oC.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These re-sults indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.
