A series of Sm doped ZnO based thermoelectric materials were prepared by mechanical alloying and spark plasma sintering.The effects of Sm doping on ZnO based thermoelectric materials were systematically studied by mea...A series of Sm doped ZnO based thermoelectric materials were prepared by mechanical alloying and spark plasma sintering.The effects of Sm doping on ZnO based thermoelectric materials were systematically studied by means of electrical and thermal properties tests combined with first principles calculations of energy band,density of states and elastic constants.The experimental results show that the substitution of Sm at Zn site could cause the valence band and conduction band moving down,and the 4f orbitals of Sm could contribute to the increase of the density of states near the Fermi level,corresponding to the increase of carrier concentration and electrical conductivity.The substitution of Sm at Zn site could cause the decrease of effective mass and Seebeck coefficient.The substitution of Sm at Zn site could lead to the decrease of Young's modulus and lattice thermal conductivity,which contribute to the decrease of thermal conductivity.Finally,the highest dimensionless thermoelectric figure of merit(ZT)value has been increased to 0.346,which is 3.48 times as pristine ZnO.展开更多
Ternary piezoelectric ceramics Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)exhibit excellent temperature stability and hold great potential for high-frequency and high-power applications.H...Ternary piezoelectric ceramics Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)exhibit excellent temperature stability and hold great potential for high-frequency and high-power applications.However,its piezoelectric performance is much lower than that of the famous binary Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-PT)system.In this work,high-performance 15PIN-50PMN-35PT piezoceramics with piezoelectric coefficient d_(33) of 700 pC/N,electromechanical coupling coefficient k_(p) of 66% and high Curie temperature Tc of 199℃ were fabricated.Effect of Samarium(Sm)doping content on the ferroelectric,dielectric,electromechanical and piezoelectric properties and structures of 15PIN-50PMN-35PT piezoelectric ceramics were investigated,and results reveal that increasing the amount of Sm doping leads to a significant decrease of d_(33),k_(p),T_(C) and other properties.This phenomenon is different from the previously reported results in Sm-doped binary PMN-PT ceramics.The room temperature and variable temperature phase structure and room temperature microstructure were studied to explain this phenomenon.展开更多
LiFePO_(4)is widely used as a stable and environmentally benign cathode material.However,its reuse potential is constrained by recycling challenges and significant performance degradation after decommissioning.Therefo...LiFePO_(4)is widely used as a stable and environmentally benign cathode material.However,its reuse potential is constrained by recycling challenges and significant performance degradation after decommissioning.Therefore,how to effectively improve the electrochemical performance of regenerated LiFePO_(4)materials and enhance their stability during cycling has become the focus of current research.In this research,Sm doping was introduced to optimize regenerated LiFePO_(4)cathode materials via a plasma ball milling assisted solid-state calcination method.Comparison between spent LiFePO_(4)and Sm-doped regenerated cathodes revealed that the appropriate level of Sm doping effectively maintained the crystal structure of LiFePO_(4).It also promoted a more uniform particle morphology and a reduced particle size,which is beneficial for shortening Li^(+)transport pathways.This enhancement significantly improved electronic conductivity,leading to enhanced electrochemical performance.The 2%Sm doped regenerated material exhibited optimal performance,achieving an initial charge-discharge specific capacity of 142.2 mAh·g^(-1)at 1 C and maintaining a capacity retention of 96.5%after 200 cycles.This conclusion is of significant importance for improving resource utilization efficiency of spent LiFePO_(4)batteries.展开更多
Nanocrystalline and amorphous La_（2–x）Sm_xMg_（16）Ni＋200wt.% Ni（x=0, 0.1, 0.2, 0.3, 0.4） alloys were prepared by mechanical milling technology. The structures of as-cast and milled alloys were investigated by X...Nanocrystalline and amorphous La_（2–x）Sm_xMg_（16）Ni＋200wt.% Ni（x=0, 0.1, 0.2, 0.3, 0.4） alloys were prepared by mechanical milling technology. The structures of as-cast and milled alloys were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Electrochemical performance of the alloy was studied by using an automatic galvanostatic system. The electrochemical impedance spectra（EIS） and Tafel polarization curves were measured by electrochemical workstation. The results indicated that the structures of the as-cast and milled alloys presented a multiphase structure with nanocrystalline and amorphous phase, moreover, transforming from nanocrystalline to amorphous phase with Sm doping. With the increase of Sm content, the maximum discharge capacity of the alloy was decreased from 922.6 to 649.1 m Ah/g, the high-rate discharge ability（HRD） was decreased, the cycle stability was strengthened, and the alloy exhibited excellent electrochemical kinetics. In addition, the charge-transfer resistance（R_（ct）） of alloy was lessened from 0.05874 to 0.02953 ？ and the limiting current density（I_L） was descended from 2.08366 to 1.04592 A/g with increasing Sm content.展开更多
The self-made MnFeO_(x) catalysts doped with cerium and samarium were prepared by impregnation method for low-temperature selective catalytic reduction(SCR)by NH3.In this work,the surface properties of the series of M...The self-made MnFeO_(x) catalysts doped with cerium and samarium were prepared by impregnation method for low-temperature selective catalytic reduction(SCR)by NH3.In this work,the surface properties of the series of MnFe-based catalysts were studied.The results indicate Sm-modified catalyst have superior low-temperature SCR activity;NO_(x) conversion maintained at nearby to 100%at 90℃ to 240℃.In addition,The N_(2) selectivity of Sm doping remains above 80%in the range of 60℃ to 150℃.In SO_(2) poisoning test,the NO_(x) conversion can be remained>90%after 10 h of reaction.The XPS,NH_(3)-TPD and H_(2)-TPR results show the catalyst with Sm doping enhances the acid sites and oxidation catalytic sites of mixed oxides serves for improving oxygen vacancies and transfer electrons.In situ diffuse reflaxions infrared Fourier transformations spectroscopy(DRIFTS)results show that NO_(x) is more easily adsorbed on the surface after Sm doping,which provided favorable conditions for the NH_(3)-SCR reaction to proceed.The reaction at the catalyst surface will follow the L-H reaction mechanism by transient reaction test.展开更多
Ce0.8Sm0.2O1.9（SDC）powder was prepared with an oxalate coprecipitation route.SDC solid solutions were sintered at various temperatures ranging from 1100~1450 ℃,and characterized by X-ray diffraction（XRD）,scanning...Ce0.8Sm0.2O1.9（SDC）powder was prepared with an oxalate coprecipitation route.SDC solid solutions were sintered at various temperatures ranging from 1100~1450 ℃,and characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,density measurements,and electrical conductivity measurements.The optimized processing parameters for densification were to uniaxially press the sample at 200~400 MPa and sinter it at 1350~1400 ℃ for 4 h.The density of the sintered pellets was 〉90% of the theoretical density;their soakage was 〈0.5%;and the average grain size was 1~2 μm.The conductivities of the typical sintered specimen were 0.0133 and 0.0211 S·cm-1 at 550 and 600 ℃,respectively;Its activation energy for ionic conductivity was 0.62 eV.The dense SDC bulk material could be used as the electrolyte layer of low temperature solid oxide fuel cells.展开更多
Samarium doped vertically aligned one dimensional ZnO nanorod（NR） arrays were grown by vapor phase transport（VPT） method through vapor solid（VS） growth process. Influence of different concentrations（0% to 8%） ...Samarium doped vertically aligned one dimensional ZnO nanorod（NR） arrays were grown by vapor phase transport（VPT） method through vapor solid（VS） growth process. Influence of different concentrations（0% to 8%） of Sm（all Sm contents in the paper are in mass fraction） on the ZnO NR arrays were investigated by X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, photoluminescence（PL）, Raman spectroscopy and vibrating sample magnetometry（VSM） techniques, respectively. X-ray diffraction studies revealed that the ZnO NR arrays were perfectly oriented along（002） crystallographic orientation with wurtzite crystal structure. Photoluminescence results showed an increase in oxygen vacancies due to increase in Sm doping. M-H curves revealed enhanced ferromagnetic behavior, and the magnetic moment values were 0.45, 0.363, 1.694, 3.613 and 2.197 emu/cm^3 for（0–8%） Sm doped ZnO NR arrays respectively. The curve revealed that paramagnetic behavior was observed for undoped ZnO NR arrays and on increasing the Sm dopant to 4%, paramagnetic switched to ferromagnetic behavior.展开更多
The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface def...The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen pressures.Recently published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder conditions.The theoretical analysis of these experimental results fits very well the experimental results of SDC and PCO.It leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the bulk.In PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and semiconducting.The surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the bulk.The reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this problem.For that we make use of the experimental data and theoretical analysis available for acceptor doped ceria.展开更多
基金by the Natural Science Foundation of Hubei Province(2021CFB009)the Guiding Project of Hubei Province in 2022 and the School Youth Fund of Wuhan Donghu University。
文摘A series of Sm doped ZnO based thermoelectric materials were prepared by mechanical alloying and spark plasma sintering.The effects of Sm doping on ZnO based thermoelectric materials were systematically studied by means of electrical and thermal properties tests combined with first principles calculations of energy band,density of states and elastic constants.The experimental results show that the substitution of Sm at Zn site could cause the valence band and conduction band moving down,and the 4f orbitals of Sm could contribute to the increase of the density of states near the Fermi level,corresponding to the increase of carrier concentration and electrical conductivity.The substitution of Sm at Zn site could cause the decrease of effective mass and Seebeck coefficient.The substitution of Sm at Zn site could lead to the decrease of Young's modulus and lattice thermal conductivity,which contribute to the decrease of thermal conductivity.Finally,the highest dimensionless thermoelectric figure of merit(ZT)value has been increased to 0.346,which is 3.48 times as pristine ZnO.
基金funded by the National Natural Science Foundation of China(Grant No.52272116)the Natural Science Foundation of Shandongg Province(No.ZR2021ME096)the Taishan Scholar Program of Shandong Province(No.tstp20240511)。
文摘Ternary piezoelectric ceramics Pb(In_(1/2)Nb_(1/2))O_(3)-Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)exhibit excellent temperature stability and hold great potential for high-frequency and high-power applications.However,its piezoelectric performance is much lower than that of the famous binary Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-PT)system.In this work,high-performance 15PIN-50PMN-35PT piezoceramics with piezoelectric coefficient d_(33) of 700 pC/N,electromechanical coupling coefficient k_(p) of 66% and high Curie temperature Tc of 199℃ were fabricated.Effect of Samarium(Sm)doping content on the ferroelectric,dielectric,electromechanical and piezoelectric properties and structures of 15PIN-50PMN-35PT piezoelectric ceramics were investigated,and results reveal that increasing the amount of Sm doping leads to a significant decrease of d_(33),k_(p),T_(C) and other properties.This phenomenon is different from the previously reported results in Sm-doped binary PMN-PT ceramics.The room temperature and variable temperature phase structure and room temperature microstructure were studied to explain this phenomenon.
基金The Yunnan Province Basic Research Program(Nos.202501AW070007 and 202201AT070184)the Yunnan Precious Metals Laboratory Technology Plan Project(YPML-20240502049)+1 种基金the High-level Talent Introduction Scientific Research Start Project of KUST(20190015)the Kunming University of Science and Technology Analysis Test Fund(2023P20221102021,2024T20180052)are gratefully acknowledged.
文摘LiFePO_(4)is widely used as a stable and environmentally benign cathode material.However,its reuse potential is constrained by recycling challenges and significant performance degradation after decommissioning.Therefore,how to effectively improve the electrochemical performance of regenerated LiFePO_(4)materials and enhance their stability during cycling has become the focus of current research.In this research,Sm doping was introduced to optimize regenerated LiFePO_(4)cathode materials via a plasma ball milling assisted solid-state calcination method.Comparison between spent LiFePO_(4)and Sm-doped regenerated cathodes revealed that the appropriate level of Sm doping effectively maintained the crystal structure of LiFePO_(4).It also promoted a more uniform particle morphology and a reduced particle size,which is beneficial for shortening Li^(+)transport pathways.This enhancement significantly improved electronic conductivity,leading to enhanced electrochemical performance.The 2%Sm doped regenerated material exhibited optimal performance,achieving an initial charge-discharge specific capacity of 142.2 mAh·g^(-1)at 1 C and maintaining a capacity retention of 96.5%after 200 cycles.This conclusion is of significant importance for improving resource utilization efficiency of spent LiFePO_(4)batteries.
基金Project supported by National Natural Science Foundation of China(51371094,51471054)Young Teachers'Training Project,School of Materials and Metallurgy,Inner Mongolia University of Science and Technology(214CY012)
文摘Nanocrystalline and amorphous La_（2–x）Sm_xMg_（16）Ni＋200wt.% Ni（x=0, 0.1, 0.2, 0.3, 0.4） alloys were prepared by mechanical milling technology. The structures of as-cast and milled alloys were investigated by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Electrochemical performance of the alloy was studied by using an automatic galvanostatic system. The electrochemical impedance spectra（EIS） and Tafel polarization curves were measured by electrochemical workstation. The results indicated that the structures of the as-cast and milled alloys presented a multiphase structure with nanocrystalline and amorphous phase, moreover, transforming from nanocrystalline to amorphous phase with Sm doping. With the increase of Sm content, the maximum discharge capacity of the alloy was decreased from 922.6 to 649.1 m Ah/g, the high-rate discharge ability（HRD） was decreased, the cycle stability was strengthened, and the alloy exhibited excellent electrochemical kinetics. In addition, the charge-transfer resistance（R_（ct）） of alloy was lessened from 0.05874 to 0.02953 ？ and the limiting current density（I_L） was descended from 2.08366 to 1.04592 A/g with increasing Sm content.
基金supported by the Fundamental Research Funds for the Central Universities(222201817001)Shanghai Sailing Program(21YF140800).
文摘The self-made MnFeO_(x) catalysts doped with cerium and samarium were prepared by impregnation method for low-temperature selective catalytic reduction(SCR)by NH3.In this work,the surface properties of the series of MnFe-based catalysts were studied.The results indicate Sm-modified catalyst have superior low-temperature SCR activity;NO_(x) conversion maintained at nearby to 100%at 90℃ to 240℃.In addition,The N_(2) selectivity of Sm doping remains above 80%in the range of 60℃ to 150℃.In SO_(2) poisoning test,the NO_(x) conversion can be remained>90%after 10 h of reaction.The XPS,NH_(3)-TPD and H_(2)-TPR results show the catalyst with Sm doping enhances the acid sites and oxidation catalytic sites of mixed oxides serves for improving oxygen vacancies and transfer electrons.In situ diffuse reflaxions infrared Fourier transformations spectroscopy(DRIFTS)results show that NO_(x) is more easily adsorbed on the surface after Sm doping,which provided favorable conditions for the NH_(3)-SCR reaction to proceed.The reaction at the catalyst surface will follow the L-H reaction mechanism by transient reaction test.
基金Project supported by the National Natural Science Foundation of China(20576063)
文摘Ce0.8Sm0.2O1.9（SDC）powder was prepared with an oxalate coprecipitation route.SDC solid solutions were sintered at various temperatures ranging from 1100~1450 ℃,and characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,density measurements,and electrical conductivity measurements.The optimized processing parameters for densification were to uniaxially press the sample at 200~400 MPa and sinter it at 1350~1400 ℃ for 4 h.The density of the sintered pellets was 〉90% of the theoretical density;their soakage was 〈0.5%;and the average grain size was 1~2 μm.The conductivities of the typical sintered specimen were 0.0133 and 0.0211 S·cm-1 at 550 and 600 ℃,respectively;Its activation energy for ionic conductivity was 0.62 eV.The dense SDC bulk material could be used as the electrolyte layer of low temperature solid oxide fuel cells.
基金supported by Department of Science and Technology,Government of India,under the Nano mission project(SR/NM/NS-113/2010-BU(G)),DST-FIST and DST-PURSE for the characterization facilities
文摘Samarium doped vertically aligned one dimensional ZnO nanorod（NR） arrays were grown by vapor phase transport（VPT） method through vapor solid（VS） growth process. Influence of different concentrations（0% to 8%） of Sm（all Sm contents in the paper are in mass fraction） on the ZnO NR arrays were investigated by X-ray diffraction（XRD）, field emission scanning electron microscopy（FESEM）, photoluminescence（PL）, Raman spectroscopy and vibrating sample magnetometry（VSM） techniques, respectively. X-ray diffraction studies revealed that the ZnO NR arrays were perfectly oriented along（002） crystallographic orientation with wurtzite crystal structure. Photoluminescence results showed an increase in oxygen vacancies due to increase in Sm doping. M-H curves revealed enhanced ferromagnetic behavior, and the magnetic moment values were 0.45, 0.363, 1.694, 3.613 and 2.197 emu/cm^3 for（0–8%） Sm doped ZnO NR arrays respectively. The curve revealed that paramagnetic behavior was observed for undoped ZnO NR arrays and on increasing the Sm dopant to 4%, paramagnetic switched to ferromagnetic behavior.
基金financially supported by the Technion V.P.for Research Fund(No.2023320)。
文摘The monomolecular surface layer of acceptor doped CeO_(2) may become neutral and metallic or charged and semiconducting.This is revealed in the theoretical analysis of the oxygen pressure dependence of the surface defects concentration in acceptor doped ceria with two different dopant types and operated under different oxygen pressures.Recently published experimental data for highly reduced Sm0.2Ce0.8O1.9-x(SDC)containing a fixed valence dopant Sm3+are very different from those published for Pr0.1Ce0.9O_(2)-x(PCO) with the variable valence dopant Pr4+/Pr3+being reduced under milder conditions.The theoretical analysis of these experimental results fits very well the experimental results of SDC and PCO.It leads to the following predictions:the highly reduced surface of SDC is metallic and neutral,the metallic surface electron density of state is gs=0.9×10^(38)J-1·m^(-2)(1.4×1015eV^(-1)·cm^(-2)),the electron effective mass is meff,s=3.3me,and the phase diagram of the reduced surface has theα(fcc)structure as in the bulk.In PCO a double layer is predicted to be formed between the surface and the bulk with the surface being negatively charged and semiconducting.The surface of PCO maintains high Pr^(3+) defect concentration as well as relative high oxygen vacancy concentration at oxygen pressures higher than in the bulk.The reasons for the difference between a metallic and semiconducting surface layer of acceptor doped CeO_(2) are reviewed,as well as the key theoretical considerations applied in coping with this problem.For that we make use of the experimental data and theoretical analysis available for acceptor doped ceria.
