Effects of interlayer composition on bonding strength and interfacial microstructure of green joined CePO_4-ZrO_2 ceramics were studied. Green bodies of 25%CePO_4/ZrO_2 and ZrO_2 ceramics were joined by using interlay...Effects of interlayer composition on bonding strength and interfacial microstructure of green joined CePO_4-ZrO_2 ceramics were studied. Green bodies of 25%CePO_4/ZrO_2 and ZrO_2 ceramics were joined by using interlayer composed of CePO_4 and ZrO_2 at 1450 ℃ for 120 min without applied pressure.The effects of CePO_4/(CePO_4+ZrO_2) ratio on the bond strength of the joints were investigated. Under the experimental conditions, the grain size of the particles grown in the joint is smaller than those in joined ceramics. The microstructure of the joint is more homogeneous than that of the matrix and without obvious cracks, pores and other defects.展开更多
The sintering and machinability of monazite-type CePO_4 ceramics were investigated. Relative density ≥98% and apparent porosity <2% were achieved when the monazite-type CePO_4 were sintered at 1500 ℃/1 h in air,a...The sintering and machinability of monazite-type CePO_4 ceramics were investigated. Relative density ≥98% and apparent porosity <2% were achieved when the monazite-type CePO_4 were sintered at 1500 ℃/1 h in air,and the maximal bending strength value (184 MPa) was achieved at this temperature. CePO_4 ceramics has a multilayer structure and an exciting 'ductility',so it can be drilled and cut with WC cutter with a small machining damage.展开更多
One-dimensional cerium phosphate （CePO4） nanorods were successfully synthesized by a facile and simple solvothermal method at 150℃ for 12 h, using Ce（NO_3）_3·6H_20 and NaH_2PO_4·2H2O as the starting mat...One-dimensional cerium phosphate （CePO4） nanorods were successfully synthesized by a facile and simple solvothermal method at 150℃ for 12 h, using Ce（NO_3）_3·6H_20 and NaH_2PO_4·2H2O as the starting materials. Phase and morphologie of the as-synthesized CePO4 products, characterized by XRD, FESEM, and TEM, were proved to be perfect and uniform hexagonal CePO_4 nanorods with aspect ratio of more than 100. The photoluminescence （PL） spectrometer was used to investigate the optical properties of the as- synthesized hexagonal CePO_4 nanorods.展开更多
The property parameters and machining output parameters were selected for machinability evaluation of machinable ceramics. Based on fuzzy evaluation theory, two-stage fuzzy evaluation approach was applied to consider ...The property parameters and machining output parameters were selected for machinability evaluation of machinable ceramics. Based on fuzzy evaluation theory, two-stage fuzzy evaluation approach was applied to consider these parameters. Two-stage fuzzy comprehensive evaluation model was proposed to evaluate machinability of machinable ceramic materials. Ce-ZrO2/CePO4 composites were fabricated and machined for evaluation of machinable ceramics. Material removal rates and specific normal grinding forces were measured. The parameters concerned with machinability were selected as alternative set. Five grades were chosen for the machinability evaluation of machnable ceramics. Machinability grades of machinable ceramics were determined through fuzzy operation. Ductile marks are observed on Ce-ZrO2/CePO4 machined surface. Five prepared Ce-ZrO2/CePO4 composites are classified as three machinability grades according to the fuzzy comprehensive evaluation results. The machinability grades of Ce-ZrO2/CePO4 composites are concerned with CePO4 content.展开更多
The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic pr...The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic properties are primarily determined by the microscopic structure,the correlation between phosphorus fixation capacity and slag structure was explored by spectroscopy(XPS),Raman spectroscopy,and ferromanganese dephosphorization experiments.The results show that the predominant species of P^(5+)are Q_(P)^(0)(PO_(4)^(3-))and Q_(P)^(1)(P_(2)O_(7)^(4-))units in the CaO^(-)SiO_(2)-Al_(2)O_(3)-MnO^(-)Ce_(2)O_(3)-P_(2)O_(5)quenched slag,and the phosphorus fixation capacity increases with the Q_(P)^(1)(P_(2)O_(7)^(4-))unit to Q_(P)^(0)(PO_(4)^(3-))unit transformation(the P-O^(0) bond to P-O^(-)bond transformation)since the electron cloud density between P and O atoms increases and the average radius of P-O bonds decreases.Especially,CaO or Ce_(2)O_(3) as a network modifier can release the O_(2)-and promote the P-O^(0) bond to P-O^(-)bond(connected to Ca^(2+),/Ce^(3+))transformation in the quenched slag.Furthermore,the phosphorus enrichment phases in the slow cooling slag are confirmed as nCa_(2)SiO_(3)-Ca_(3)P_(2)O_(8)(nC_(2)S-C3P)and CePO_(4) solid solutions by the scan electron microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive spectrometer(EDS)methods.The re sults show Ce_(2)O_(3) can depolymerize the polyphosphate structure partially replacing CaO after introducing Ce_(2)O_(3) into CaO based slag because of its strong ability to donate electrons.The above results not only help to understand the dependence of phosphorus fixation capacity on slag composition from a structural view,but also provide the theoretical guidance for optimizing the composition of Ce_(2)O_(3)-containing dephosphorization slag.展开更多
Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature rang...Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature range of 80 to 400°C.The catalytic efficiencies of the three catalysts are as follow:CePO_(4)>CeVO_(4)>Ce_(2)(SO_(4))_(3),which is in agreement with their abilities of NH_(3)adsorption capacities.The highest NO conversion rate of CePO_(4)could reach about 95%,and the catalyst had more than 90%NO conversion rate between 260 and 320°C.The effect of PO_(4)^(3–),VO_(4)^(3–)and SO_(4)^(2–)on NH_(3)-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis,NH_(3)temperature programmed desorption,H2 temperature programmed reduction and field emission scanning electron microscopy tests.The key factors that can enhance the SCR are the existence of Ce4+,large NH_(3)adsorption capacity,high and early H2 consumptions,and suitable microstructures for gas adsorption.Finally,CePO_(4)and CeVO_(4)catalysts also exhibited relatively strong tolerance of SO2,and the upward trend about 8%was detected due to the sulfation enhancement by SO2 for Ce_(2)(SO_(4))3.展开更多
CePO_(4):Tb^(3+)nanorods were successfully obtained via a simple hydrothermal method and combined with carbon dots(CDs)to obtain CDs@CePO_(4):Tb^(3+)nanorods.Due to the combination of CDs,the emission intensity of CDs...CePO_(4):Tb^(3+)nanorods were successfully obtained via a simple hydrothermal method and combined with carbon dots(CDs)to obtain CDs@CePO_(4):Tb^(3+)nanorods.Due to the combination of CDs,the emission intensity of CDs@CePO_(4):Tb^(3+)nanorods increases about 92 times,compared with that of CePO_(4):Tb^(3+)nanorods.The combination of CDs and CePO_(4):Tb^(3+)nanorods was confirmed by Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and so on.The mechanism of luminescence enhancement may be attributed to some aspects:the formation of hexagonal phase results in the increase of crystal field symmetry,and the energy transfer among CDs,Ce^(3+)and Tb^(3+)ions,which causes the Tb^(3+)ions in CDs@CePO_(4):Tb^(3+)nano rods to obtain mo re excited energy and less non-radiative atte nuation co mpared to CePO_(4):Tb^(3+)nano rods.The luminescence enhancement strategy through combination of CDs would provide a simple and effective approach for other rare earth ions doped luminescent materials.展开更多
Revealing the active species of the catalyst is conducive to the design of more efficient catalyst.Herein,we tried to demonstrate the roles of amorphous and crystalline structures on CePO_(4)catalyst during selective ...Revealing the active species of the catalyst is conducive to the design of more efficient catalyst.Herein,we tried to demonstrate the roles of amorphous and crystalline structures on CePO_(4)catalyst during selective catalytic reduction(SCR)of NO_(x)by NH_(3).Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO_(4).Both amorphous and crystalline CePO_(4)species on CePO-X samples can provide acid sites for NH_(3)adsorption,but the former can provide more acid sites.The superior redox property of surface amorphous CePO_(4)species contributes to its high NH_(3)-SCR activity at low temperature,but it also leads to the decrease of high temperature(>350℃)NH_(3)-SCR activity due to the oxidation of NH_(3).In contrast,crystalline CePO_(4)species shows high activity only at high temperature because of its poor redox property.Therefo re,it can be inferred that amo rphous and crystalline structures on CePO_(4)catalyst can be the efficient active species of NH_(3)-SCR at low and high temperature,respectively.展开更多
Non-toxic rare earth(RE) composite materials are promising and active in optoelectronic fields,such as pigment.In this work,Na ions doped γ-Ce_(2) S_(3) pigments were synthesized by solid-phase vulcanization and foll...Non-toxic rare earth(RE) composite materials are promising and active in optoelectronic fields,such as pigment.In this work,Na ions doped γ-Ce_(2) S_(3) pigments were synthesized by solid-phase vulcanization and followed by in-situ synthesis to prepare an outer layer of CePO_(4) film.The characterizations of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),solid state nuclear magnetic resonance(NMR) indicate that Na-dopedγ-Ce_(2) S_(3) and CePO_(4) uniformly and tightly coated core-shell structure was successfully synthesized.The thermogravimetric analysis(TG) and reflection spectrum(RS) reveal that the CePO_(4) coating significantly improves the colorant and thermal stability performance of γ-Ce_(2) S_(3) .The excellent color quality of γ-Ce_(2) S_(3) @CePO_(4)(L*=45.16,a*=55.94.b*=44.53) is achieved and the red color(L*=43.82,a*=49.79,b*=38.04) is still retained even if the sample is heated in air at 400℃ for 30 min.展开更多
文摘Effects of interlayer composition on bonding strength and interfacial microstructure of green joined CePO_4-ZrO_2 ceramics were studied. Green bodies of 25%CePO_4/ZrO_2 and ZrO_2 ceramics were joined by using interlayer composed of CePO_4 and ZrO_2 at 1450 ℃ for 120 min without applied pressure.The effects of CePO_4/(CePO_4+ZrO_2) ratio on the bond strength of the joints were investigated. Under the experimental conditions, the grain size of the particles grown in the joint is smaller than those in joined ceramics. The microstructure of the joint is more homogeneous than that of the matrix and without obvious cracks, pores and other defects.
文摘The sintering and machinability of monazite-type CePO_4 ceramics were investigated. Relative density ≥98% and apparent porosity <2% were achieved when the monazite-type CePO_4 were sintered at 1500 ℃/1 h in air,and the maximal bending strength value (184 MPa) was achieved at this temperature. CePO_4 ceramics has a multilayer structure and an exciting 'ductility',so it can be drilled and cut with WC cutter with a small machining damage.
基金Funded by the Scientism and Technology Project of Zhejiang Provincial Science Technology Department(2013C31050)the Zhejiang Provincial Natural Science Foundation of China(Y12E090007)+1 种基金the Scientism and Technology Project of Zhoushan(2012C33007)the National Natural Science Foundation of China(51102289)
文摘One-dimensional cerium phosphate （CePO4） nanorods were successfully synthesized by a facile and simple solvothermal method at 150℃ for 12 h, using Ce（NO_3）_3·6H_20 and NaH_2PO_4·2H2O as the starting materials. Phase and morphologie of the as-synthesized CePO4 products, characterized by XRD, FESEM, and TEM, were proved to be perfect and uniform hexagonal CePO_4 nanorods with aspect ratio of more than 100. The photoluminescence （PL） spectrometer was used to investigate the optical properties of the as- synthesized hexagonal CePO_4 nanorods.
基金Project(50305023) supported by the National Natural Science Foundation of China
文摘The property parameters and machining output parameters were selected for machinability evaluation of machinable ceramics. Based on fuzzy evaluation theory, two-stage fuzzy evaluation approach was applied to consider these parameters. Two-stage fuzzy comprehensive evaluation model was proposed to evaluate machinability of machinable ceramic materials. Ce-ZrO2/CePO4 composites were fabricated and machined for evaluation of machinable ceramics. Material removal rates and specific normal grinding forces were measured. The parameters concerned with machinability were selected as alternative set. Five grades were chosen for the machinability evaluation of machnable ceramics. Machinability grades of machinable ceramics were determined through fuzzy operation. Ductile marks are observed on Ce-ZrO2/CePO4 machined surface. Five prepared Ce-ZrO2/CePO4 composites are classified as three machinability grades according to the fuzzy comprehensive evaluation results. The machinability grades of Ce-ZrO2/CePO4 composites are concerned with CePO4 content.
基金Project supported by the National Natural Science Foundation of China(51874082)NSFC-Liaoning Joint Fund(U1908224)。
文摘The phosphorus fixation capacity of some slag systems,such as Ce_(2)O_(3)-containing slag,has hardly been investigated from a thermodynamics view due to the lack of relevant thermodynamic data.Since the macroscopic properties are primarily determined by the microscopic structure,the correlation between phosphorus fixation capacity and slag structure was explored by spectroscopy(XPS),Raman spectroscopy,and ferromanganese dephosphorization experiments.The results show that the predominant species of P^(5+)are Q_(P)^(0)(PO_(4)^(3-))and Q_(P)^(1)(P_(2)O_(7)^(4-))units in the CaO^(-)SiO_(2)-Al_(2)O_(3)-MnO^(-)Ce_(2)O_(3)-P_(2)O_(5)quenched slag,and the phosphorus fixation capacity increases with the Q_(P)^(1)(P_(2)O_(7)^(4-))unit to Q_(P)^(0)(PO_(4)^(3-))unit transformation(the P-O^(0) bond to P-O^(-)bond transformation)since the electron cloud density between P and O atoms increases and the average radius of P-O bonds decreases.Especially,CaO or Ce_(2)O_(3) as a network modifier can release the O_(2)-and promote the P-O^(0) bond to P-O^(-)bond(connected to Ca^(2+),/Ce^(3+))transformation in the quenched slag.Furthermore,the phosphorus enrichment phases in the slow cooling slag are confirmed as nCa_(2)SiO_(3)-Ca_(3)P_(2)O_(8)(nC_(2)S-C3P)and CePO_(4) solid solutions by the scan electron microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive spectrometer(EDS)methods.The re sults show Ce_(2)O_(3) can depolymerize the polyphosphate structure partially replacing CaO after introducing Ce_(2)O_(3) into CaO based slag because of its strong ability to donate electrons.The above results not only help to understand the dependence of phosphorus fixation capacity on slag composition from a structural view,but also provide the theoretical guidance for optimizing the composition of Ce_(2)O_(3)-containing dephosphorization slag.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.52102367)And the tests of XRD and XPS were supported by Research and Test Center of Materials,Wuhan University of TechnologyDRIFTS,TPD and TPR tests were supported by State Key Laboratory of Silicate Materials for Architectures,Wuhan University of Technology.
文摘Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature range of 80 to 400°C.The catalytic efficiencies of the three catalysts are as follow:CePO_(4)>CeVO_(4)>Ce_(2)(SO_(4))_(3),which is in agreement with their abilities of NH_(3)adsorption capacities.The highest NO conversion rate of CePO_(4)could reach about 95%,and the catalyst had more than 90%NO conversion rate between 260 and 320°C.The effect of PO_(4)^(3–),VO_(4)^(3–)and SO_(4)^(2–)on NH_(3)-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis,NH_(3)temperature programmed desorption,H2 temperature programmed reduction and field emission scanning electron microscopy tests.The key factors that can enhance the SCR are the existence of Ce4+,large NH_(3)adsorption capacity,high and early H2 consumptions,and suitable microstructures for gas adsorption.Finally,CePO_(4)and CeVO_(4)catalysts also exhibited relatively strong tolerance of SO2,and the upward trend about 8%was detected due to the sulfation enhancement by SO2 for Ce_(2)(SO_(4))3.
基金Project supported by the National Natural Science Foundation of China(51572303,52002117)。
文摘CePO_(4):Tb^(3+)nanorods were successfully obtained via a simple hydrothermal method and combined with carbon dots(CDs)to obtain CDs@CePO_(4):Tb^(3+)nanorods.Due to the combination of CDs,the emission intensity of CDs@CePO_(4):Tb^(3+)nanorods increases about 92 times,compared with that of CePO_(4):Tb^(3+)nanorods.The combination of CDs and CePO_(4):Tb^(3+)nanorods was confirmed by Fourier transform infrared spectroscopy(FTIR),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and so on.The mechanism of luminescence enhancement may be attributed to some aspects:the formation of hexagonal phase results in the increase of crystal field symmetry,and the energy transfer among CDs,Ce^(3+)and Tb^(3+)ions,which causes the Tb^(3+)ions in CDs@CePO_(4):Tb^(3+)nano rods to obtain mo re excited energy and less non-radiative atte nuation co mpared to CePO_(4):Tb^(3+)nano rods.The luminescence enhancement strategy through combination of CDs would provide a simple and effective approach for other rare earth ions doped luminescent materials.
基金Project supported by the Fundamental Research Funds for the Central Universities(30919011220)the Key Project of Jiangsu Province Programs for Research and Development(BE2019115)Top-notch Academic Programs Project of Jiangsu Higher Education Institutions。
文摘Revealing the active species of the catalyst is conducive to the design of more efficient catalyst.Herein,we tried to demonstrate the roles of amorphous and crystalline structures on CePO_(4)catalyst during selective catalytic reduction(SCR)of NO_(x)by NH_(3).Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO_(4).Both amorphous and crystalline CePO_(4)species on CePO-X samples can provide acid sites for NH_(3)adsorption,but the former can provide more acid sites.The superior redox property of surface amorphous CePO_(4)species contributes to its high NH_(3)-SCR activity at low temperature,but it also leads to the decrease of high temperature(>350℃)NH_(3)-SCR activity due to the oxidation of NH_(3).In contrast,crystalline CePO_(4)species shows high activity only at high temperature because of its poor redox property.Therefo re,it can be inferred that amo rphous and crystalline structures on CePO_(4)catalyst can be the efficient active species of NH_(3)-SCR at low and high temperature,respectively.
基金Project supported by the Natural Science Foundation of Zhejiang Province,China(LQ21E020006)the National Key Research and Development Program of China(2019YFA0709101)Opening Fund of State Key Laboratory of Rare Earth Resource Utilization,China(Changchun Institute of Applied Chemistry)(RERU2018012)。
文摘Non-toxic rare earth(RE) composite materials are promising and active in optoelectronic fields,such as pigment.In this work,Na ions doped γ-Ce_(2) S_(3) pigments were synthesized by solid-phase vulcanization and followed by in-situ synthesis to prepare an outer layer of CePO_(4) film.The characterizations of X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),solid state nuclear magnetic resonance(NMR) indicate that Na-dopedγ-Ce_(2) S_(3) and CePO_(4) uniformly and tightly coated core-shell structure was successfully synthesized.The thermogravimetric analysis(TG) and reflection spectrum(RS) reveal that the CePO_(4) coating significantly improves the colorant and thermal stability performance of γ-Ce_(2) S_(3) .The excellent color quality of γ-Ce_(2) S_(3) @CePO_(4)(L*=45.16,a*=55.94.b*=44.53) is achieved and the red color(L*=43.82,a*=49.79,b*=38.04) is still retained even if the sample is heated in air at 400℃ for 30 min.
