Ce0.8Sm0.2O1.9-δ-La0.9Sr0.1Ga0.8Mg0.2O3-δ（SDC-LSGM）is prepared by the glycine-nitrate process（GNP）.SDC-LSGM composite electrolyte samples with different weight ratios are prepared by the co-combustion method so ...Ce0.8Sm0.2O1.9-δ-La0.9Sr0.1Ga0.8Mg0.2O3-δ（SDC-LSGM）is prepared by the glycine-nitrate process（GNP）.SDC-LSGM composite electrolyte samples with different weight ratios are prepared by the co-combustion method so as to obtain homogeneous nano-sized precursor powders. The X-ray diffraction （XRD） and the scan electron microscope （SEM） are used to investigate the phases and microstructures. The measurements and analyses of oxygen ionic conductivity of SDC-LSGM are carried out through the four-terminal direct current （DC） method and the electrochemical impendence spectroscopy, respectively. The optimum weight ratio of SDC-LSGM is 8∶2, of which the ionic conductivity is 0.113 S/cm at 800℃ and the conductivity activation energy is 0.620 eV. The impendence spectra shows that the grain boundary resistance becomes the main barrier for the ionic conductivity of electrolyte at lower temperatures. The appropriate introduction of LSGM to the electrolyte SDC can not only decrease the electronic conductivity but also improve the conditions of the grain and grain boundary, which is advantageous to cause an increase in oxygen ionic conductivity.展开更多
The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conduc...The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conductivities of high-entropy ceramics(HECs).Although RE_(3)MO_(7) (RE represents rare-earth elements;M is Ta or Nb) ceramics have been widely studied for use in thermal barrier coatings and solid oxide fuel cells,their application scope can be broadened through the effective manipulation of the thermal/oxygen ionic conductivities.Herein,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))_(3)Ta_(1/2)Nb_(1/2)O_(7) HECs are designed and synthesized.These ceramics exhibit lower thermal conductivity and higher oxygen ionic conductivity than pristine ordered RE_(3)MO_(7) ceramics.Characterization results prove that high-entropy effects in the prepared material enhance atomic displacement parameters(ADPs),causing an increase in the oxygen ionic conductivity by a factor of 10 and enhancement in the phonon scattering rate,thereby reducing thermal conductivity by increasing ADPs.The ADPs can act as an indicator of the anharmonic vibration strength of the lattice,affecting the thermal/oxygen ionic conductivity and thermal expansion coefficient.Furthermore,in nano-indentation tests,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))3Ta_(1/2)Nb_(1/2)O_(7) HECs show high hardness(11.8 GPa),toughness(2.0 MPa·m^(1/2)),and modulus(215.0 GPa),which are beneficial for structural/functional applications.Overall,the obtained results indicate that thermal/oxygen ionic transport mechanisms can be used to further improve the properties and thereby expand the application scope of various HECs.展开更多
Solid electrolytes(CeO2)0.7-x(MO)x (La2O3) 0.3(M = Mg,Ca,Sr)were synthesized.Their crystal structure,conductivity, XPS spectrum,ionic transferance number and the V-1 curve of the obtained fuel cell were measured.(CeO2...Solid electrolytes(CeO2)0.7-x(MO)x (La2O3) 0.3(M = Mg,Ca,Sr)were synthesized.Their crystal structure,conductivity, XPS spectrum,ionic transferance number and the V-1 curve of the obtained fuel cell were measured.(CeO2)0.7z (La2O3)0.3 doped with Ca2+,Mg2+,and Sr2+can perform the oxygen ionic electrolyte,and so enhance the open voltage and power output of the fuel cell.展开更多
Composite oxide ionic conductors consisting of Zr_(0.85)Y_(0.15)O_(1.925)(YSZ)and La_(9.33)Si_(6)O_(26)(LSO)have been synthesized by a modified coprecipitation method.X-ray diffraction,electron microscope,and complex ...Composite oxide ionic conductors consisting of Zr_(0.85)Y_(0.15)O_(1.925)(YSZ)and La_(9.33)Si_(6)O_(26)(LSO)have been synthesized by a modified coprecipitation method.X-ray diffraction,electron microscope,and complex impedance were adopted to investigate the phase component,microstructures,and conductivities,respectively.The results show that the average grain sizes of the composite powders and as-sintered pellets are less than 20 nm and 200 nm,respectively.The conductivity of the composite materials composed of 94 wt%YSZ and 6 wt%LSO is 0.215 S/cm at 700℃.The conductivity of the composite is three times higher than that of the polycrystalline YSZ and has two orders in magnitude higher than that of the polycrystalline LSO at 700℃.By analyzing the impedance spectra and modulus spectra,the grain-boundary effect on the conductivity improvement is investigated and the conductive mechanisms of the composite materials are discussed.展开更多
基金The National Basic Research Program of China (973 Program) (No.2007CB936300)the Natural Science Foundation of Jiangsu Province (No.BK2009293)
文摘Ce0.8Sm0.2O1.9-δ-La0.9Sr0.1Ga0.8Mg0.2O3-δ（SDC-LSGM）is prepared by the glycine-nitrate process（GNP）.SDC-LSGM composite electrolyte samples with different weight ratios are prepared by the co-combustion method so as to obtain homogeneous nano-sized precursor powders. The X-ray diffraction （XRD） and the scan electron microscope （SEM） are used to investigate the phases and microstructures. The measurements and analyses of oxygen ionic conductivity of SDC-LSGM are carried out through the four-terminal direct current （DC） method and the electrochemical impendence spectroscopy, respectively. The optimum weight ratio of SDC-LSGM is 8∶2, of which the ionic conductivity is 0.113 S/cm at 800℃ and the conductivity activation energy is 0.620 eV. The impendence spectra shows that the grain boundary resistance becomes the main barrier for the ionic conductivity of electrolyte at lower temperatures. The appropriate introduction of LSGM to the electrolyte SDC can not only decrease the electronic conductivity but also improve the conditions of the grain and grain boundary, which is advantageous to cause an increase in oxygen ionic conductivity.
基金financially supported by the National Natural Science Foundation of China(No.52562006 and No.52502065)Yunnan Major Scientific and Technological Projects(No.202302AG050010)Yunnan Province Innovation Team(No.202305AS350018)
文摘The high-entropy engineering has emerged as a novel method for manipulating various properties of ceramics.Herein,the enhancement of atomic displacements was shown to effectively tailor the thermal/oxygen ionic conductivities of high-entropy ceramics(HECs).Although RE_(3)MO_(7) (RE represents rare-earth elements;M is Ta or Nb) ceramics have been widely studied for use in thermal barrier coatings and solid oxide fuel cells,their application scope can be broadened through the effective manipulation of the thermal/oxygen ionic conductivities.Herein,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))_(3)Ta_(1/2)Nb_(1/2)O_(7) HECs are designed and synthesized.These ceramics exhibit lower thermal conductivity and higher oxygen ionic conductivity than pristine ordered RE_(3)MO_(7) ceramics.Characterization results prove that high-entropy effects in the prepared material enhance atomic displacement parameters(ADPs),causing an increase in the oxygen ionic conductivity by a factor of 10 and enhancement in the phonon scattering rate,thereby reducing thermal conductivity by increasing ADPs.The ADPs can act as an indicator of the anharmonic vibration strength of the lattice,affecting the thermal/oxygen ionic conductivity and thermal expansion coefficient.Furthermore,in nano-indentation tests,(Sm_(1/5)Eu_(1/5)Gd_(1/5)Dy_(1/5)Ho_(1/5))3Ta_(1/2)Nb_(1/2)O_(7) HECs show high hardness(11.8 GPa),toughness(2.0 MPa·m^(1/2)),and modulus(215.0 GPa),which are beneficial for structural/functional applications.Overall,the obtained results indicate that thermal/oxygen ionic transport mechanisms can be used to further improve the properties and thereby expand the application scope of various HECs.
文摘Solid electrolytes(CeO2)0.7-x(MO)x (La2O3) 0.3(M = Mg,Ca,Sr)were synthesized.Their crystal structure,conductivity, XPS spectrum,ionic transferance number and the V-1 curve of the obtained fuel cell were measured.(CeO2)0.7z (La2O3)0.3 doped with Ca2+,Mg2+,and Sr2+can perform the oxygen ionic electrolyte,and so enhance the open voltage and power output of the fuel cell.
基金the National Nature Science Foundation of China(Nos.50872155 and 51172287)。
文摘Composite oxide ionic conductors consisting of Zr_(0.85)Y_(0.15)O_(1.925)(YSZ)and La_(9.33)Si_(6)O_(26)(LSO)have been synthesized by a modified coprecipitation method.X-ray diffraction,electron microscope,and complex impedance were adopted to investigate the phase component,microstructures,and conductivities,respectively.The results show that the average grain sizes of the composite powders and as-sintered pellets are less than 20 nm and 200 nm,respectively.The conductivity of the composite materials composed of 94 wt%YSZ and 6 wt%LSO is 0.215 S/cm at 700℃.The conductivity of the composite is three times higher than that of the polycrystalline YSZ and has two orders in magnitude higher than that of the polycrystalline LSO at 700℃.By analyzing the impedance spectra and modulus spectra,the grain-boundary effect on the conductivity improvement is investigated and the conductive mechanisms of the composite materials are discussed.
