Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were...Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.展开更多
Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and t...Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.展开更多
A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and elec...A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and electro- structures, electrical con- on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450℃ where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac- terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700℃, A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm2 at 700 ℃ with humidified hydrogen fuel and static air oxidant.展开更多
Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinyl pyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after doped with LiClO4, TCNQ or LiClO4 and TCNQ were ...Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinyl pyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after doped with LiClO4, TCNQ or LiClO4 and TCNQ were investigated. Effects of LiClO4 and TCNQ concentrations on the conductivity of PEO/P2VP/LiClO4 or TCNQ blend were studied. The ionic conductivity of PEO/P2VP/LiClO4 blend increases with increasing PEO content. At a Li/ethylene bride molar ratio of 0.10 and a TCNQ/2-vinyl pyridine molar ratio of 0.5, the mixed conductivity of PEO/P2VP/LiClO4/TCNQ is higher than the total of ionic conductivity of PEO/P2VP/LiClO4 and electronic conductivity of PEO/P2VP/TCNQ when the weight ratio of PEO and P2VP is 6/4 or 5/5. Scanning electron microscopy (SEM) on the broken cross-section of the PEO/P2VP/LiClO4 blend and differential scanning calorimetry (DSC) results show that LiClO4 could act as a compatibilizer in the blend.展开更多
BaFeO_(3-δ)-derived perovskites are promising cathodes for intermediate temperature solid oxide fuel cells.The activity of these perovskites depends on the number of oxygen vacancies in their lattice,which can be tun...BaFeO_(3-δ)-derived perovskites are promising cathodes for intermediate temperature solid oxide fuel cells.The activity of these perovskites depends on the number of oxygen vacancies in their lattice,which can be tuned by cationic substitution.Our first-principle calculations show that Ag is a promising substitute for the Fe site,resulting in a reduced oxygen vacancy formation energy compared with the pristine BaFeO_(3-δ).Ag has limited solubility in perovskites,and its introduction generates an Ag metal secondary phase,which influences the cathode performances.In this work,we investigate the matter,using a Ba0:9La0:1Fe_(1-x)AgxO_(3-δ)series of materials as a case study.Acknowledging the limited solubility of Ag in Ba0:9La0:1Fe_(1-x)AgxO_(3-δ),we aim to distinguish the effects of Ag substitution from those of the Ag secondary phase.We observed that Ag substitution increases the number of oxygen vacancies,confirming our calculations,and facilitates the oxygen incorporation.However,Ag substitution lowers the number of holes,in this way reducing the electronic p-type conductivity.On the other hand,Ag metal positively affects the electronic conductivity and helps the redistribution of the electronic charge at the cathode-electrolyte interface.展开更多
PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula...PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.展开更多
A series of compounds La2Mo2-xSnxO9-6 （x=0-0.3） have been synthesized by solid-state reaction technique. Materials have been characterized by XRD, SEM, DSC and impedance study. In the temperature regime 520℃-590 ℃...A series of compounds La2Mo2-xSnxO9-6 （x=0-0.3） have been synthesized by solid-state reaction technique. Materials have been characterized by XRD, SEM, DSC and impedance study. In the temperature regime 520℃-590 ℃, the specimens with x〈0.05 have the conductivity higher than La2Mo2O9. Conductivity of Sn-doped compound decreases consistently with increasing Sn-doping, compared to the undoped compound both below and above phase transition, barring the specimens with x〈 0.05, where conductivity values remains almost same as that of undoped specimen in high temperature region. In the intermediate temperature regime （520℃-590℃）, the conductivity of doped compounds increases for x〈0.05 as compared to parent compound. Also, there is no indication of phase stabilization with Sn-doping in this compound even with the highest doping level, x=0.3. Electric modulus analysis suggests that thermally activated oxygen ion hopping mechanism is responsible for the conduction in Sn-doped compound.展开更多
Manipulating the superconducting states of high transition temperature(high-Tc)cuprate superconductors in an efficient and reliable way is of great importance for their applications in next-generation electronics.Here...Manipulating the superconducting states of high transition temperature(high-Tc)cuprate superconductors in an efficient and reliable way is of great importance for their applications in next-generation electronics.Here,employing ionic liquid gating,a selective control of volatile and non-volatile superconductivity is achieved in pristine insulating Pr2CuO4±δ(PCO)films,based on two distinct mechanisms.Firstly,with positive electric fields,the film can be reversibly switched between superconducting and non-superconducting states,attributed to the carrier doping effect.Secondly,the film becomes more resistive by applying negative bias voltage up to-4V,but strikingly,a non-volatile superconductivity is achieved once the gate voltage is removed.Such phenomenon represents a distinctive route of manipulating superconductivity in PCO,resulting from the doping healing of oxygen vacancies in copper-oxygen planes as unravelled by high-resolution scanning transmission electron microscope and in situ X-ray diffraction experiments.The effective manipulation of volatile/non-volatile superconductivity in the same parent cuprate brings more functionalities to superconducting electronics,as well as supplies flexible samples for investigating the nature of quantum phase transitions in high-Tcsuperconductors.展开更多
Comb poly(siloxane-g-ethylene oxide)(PSi-PE)with high chain segmental mobility,as a plasticizer,was introduced into poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate)(PLiAMPS)-based semi-interpenetrating polymer ...Comb poly(siloxane-g-ethylene oxide)(PSi-PE)with high chain segmental mobility,as a plasticizer,was introduced into poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate)(PLiAMPS)-based semi-interpenetrating polymer network single-ion conductors.The structures of PSi-PE and PLiAMPS were characterized by FTIR spectroscopy.The distribution of PSi-PE in polyelectrolyte matrix was investigated through observing the residual surface morphology of conductor membrane after being etched by toluene.AC impedance and dielectric behavior measurements were used to investigate the impact of PSi-PE on the ionic conductivity and to analyze the mechanism of conductivity variation.Compared with the unplasticized membranes,the ionic conductivity of the membrane with the addition of 35 wt.%PSi-PE was improved by 20 times.Meanwhile,the dielectric constant(ε)of the membrane was increased to 1330 and the relaxation time was decreased to 0.012 s.The changes of dielectric properties reflect directly the effect of PSi-PE on the dissociation ability of Liþand the chain segmental mobility,which well explains the reasons of ionic conductivity variation.展开更多
基金Project supported by the National Basic Research Program of China (Grant No.2010CB832902)the Key Program of the National Natural Science Foundation of China (Grant No.10835010)the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (Grant No.KJCX2-YW-N35)
文摘Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.
基金Supported by the Joint Funds of NSFC-Guangdong of China(U0834004)the Natural Science Foundation of Guangdong Province(06025657)
文摘Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La10-xVx(SiO4) 6O3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC) ,X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800°C,a relatively low temperature in comparison to 1500°C with the conventional solid-state method.The ceramic pellets sintered at 1200°C for 5 h showed a higher relative density than La9.33Si6O26 pellets sintered at 1400°C for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.
文摘A cobalt-free perovskite-type Ba0.5Sr0.5A10.1Fe0.9O3-δ （BSAF） chemically studied as solid oxide fuel cell （SOFC） cathode. The ductivity, and electrode polarizations in symmetrical cell based is developed and electro- structures, electrical con- on mixed ion conducting electrolyte were investigated, respectively. The temperature dependence of conductivity of BSAF in air shows a typical semiconductor behavior with positive temperature coefficient up to 450℃ where the conductivity reaches 14.0 S/cm while above this temperature the negative temperature coefficient dominates the total conductivity. Electrochemical charac- terizations show desirable polarization resistance of BSAF cathode in a symmetric cell based on mixed ion conducting electrolyte at 650-700℃, A single SOFC with BSAF cathode shows OCV of 1.0 V and maximum output of 420 mW/cm2 at 700 ℃ with humidified hydrogen fuel and static air oxidant.
基金Project supported by the National Natural Science Foundation of China.
文摘Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinyl pyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after doped with LiClO4, TCNQ or LiClO4 and TCNQ were investigated. Effects of LiClO4 and TCNQ concentrations on the conductivity of PEO/P2VP/LiClO4 or TCNQ blend were studied. The ionic conductivity of PEO/P2VP/LiClO4 blend increases with increasing PEO content. At a Li/ethylene bride molar ratio of 0.10 and a TCNQ/2-vinyl pyridine molar ratio of 0.5, the mixed conductivity of PEO/P2VP/LiClO4/TCNQ is higher than the total of ionic conductivity of PEO/P2VP/LiClO4 and electronic conductivity of PEO/P2VP/TCNQ when the weight ratio of PEO and P2VP is 6/4 or 5/5. Scanning electron microscopy (SEM) on the broken cross-section of the PEO/P2VP/LiClO4 blend and differential scanning calorimetry (DSC) results show that LiClO4 could act as a compatibilizer in the blend.
基金The authors gratefully acknowledge the Research Grant Council of Hong Kong for support through the projects 16201820,and 16206019.
文摘BaFeO_(3-δ)-derived perovskites are promising cathodes for intermediate temperature solid oxide fuel cells.The activity of these perovskites depends on the number of oxygen vacancies in their lattice,which can be tuned by cationic substitution.Our first-principle calculations show that Ag is a promising substitute for the Fe site,resulting in a reduced oxygen vacancy formation energy compared with the pristine BaFeO_(3-δ).Ag has limited solubility in perovskites,and its introduction generates an Ag metal secondary phase,which influences the cathode performances.In this work,we investigate the matter,using a Ba0:9La0:1Fe_(1-x)AgxO_(3-δ)series of materials as a case study.Acknowledging the limited solubility of Ag in Ba0:9La0:1Fe_(1-x)AgxO_(3-δ),we aim to distinguish the effects of Ag substitution from those of the Ag secondary phase.We observed that Ag substitution increases the number of oxygen vacancies,confirming our calculations,and facilitates the oxygen incorporation.However,Ag substitution lowers the number of holes,in this way reducing the electronic p-type conductivity.On the other hand,Ag metal positively affects the electronic conductivity and helps the redistribution of the electronic charge at the cathode-electrolyte interface.
基金supported by the National Research Foundation (NRF) grant funded by the Korea government (NRF2022R1C1C1007619, NRF-2021M3H4A1A01002921, NRF2021M3I3A1084292)supported by the KIST Institutional Program (Project No. 2E32592-23-069)。
文摘PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF < Nd BSCF < Gd BSCF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBSCF cathodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.
文摘A series of compounds La2Mo2-xSnxO9-6 （x=0-0.3） have been synthesized by solid-state reaction technique. Materials have been characterized by XRD, SEM, DSC and impedance study. In the temperature regime 520℃-590 ℃, the specimens with x〈0.05 have the conductivity higher than La2Mo2O9. Conductivity of Sn-doped compound decreases consistently with increasing Sn-doping, compared to the undoped compound both below and above phase transition, barring the specimens with x〈 0.05, where conductivity values remains almost same as that of undoped specimen in high temperature region. In the intermediate temperature regime （520℃-590℃）, the conductivity of doped compounds increases for x〈0.05 as compared to parent compound. Also, there is no indication of phase stabilization with Sn-doping in this compound even with the highest doping level, x=0.3. Electric modulus analysis suggests that thermally activated oxygen ion hopping mechanism is responsible for the conduction in Sn-doped compound.
基金supported by the National Key Basic Research Program of China(2015CB921000,2016YFA0300301,2017YFA0302902,2017YFA0303003 and 2018YFB0704102)the National Natural Science Foundation of China(11674374 and 11834016)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB25000000)the Key Research Program of Frontier Sciences,CAS(QYZDB-SSW-SLH008 and QYZDY-SSW-SLH001)CAS Interdisciplinary Innovation Teambenefited from the bilateral collaboration F.R.S.-FNRS/NSFC(V4/345-DeM-229)。
文摘Manipulating the superconducting states of high transition temperature(high-Tc)cuprate superconductors in an efficient and reliable way is of great importance for their applications in next-generation electronics.Here,employing ionic liquid gating,a selective control of volatile and non-volatile superconductivity is achieved in pristine insulating Pr2CuO4±δ(PCO)films,based on two distinct mechanisms.Firstly,with positive electric fields,the film can be reversibly switched between superconducting and non-superconducting states,attributed to the carrier doping effect.Secondly,the film becomes more resistive by applying negative bias voltage up to-4V,but strikingly,a non-volatile superconductivity is achieved once the gate voltage is removed.Such phenomenon represents a distinctive route of manipulating superconductivity in PCO,resulting from the doping healing of oxygen vacancies in copper-oxygen planes as unravelled by high-resolution scanning transmission electron microscope and in situ X-ray diffraction experiments.The effective manipulation of volatile/non-volatile superconductivity in the same parent cuprate brings more functionalities to superconducting electronics,as well as supplies flexible samples for investigating the nature of quantum phase transitions in high-Tcsuperconductors.
文摘Comb poly(siloxane-g-ethylene oxide)(PSi-PE)with high chain segmental mobility,as a plasticizer,was introduced into poly(lithium 2-acrylamido-2-methyl-1-propanesulfonate)(PLiAMPS)-based semi-interpenetrating polymer network single-ion conductors.The structures of PSi-PE and PLiAMPS were characterized by FTIR spectroscopy.The distribution of PSi-PE in polyelectrolyte matrix was investigated through observing the residual surface morphology of conductor membrane after being etched by toluene.AC impedance and dielectric behavior measurements were used to investigate the impact of PSi-PE on the ionic conductivity and to analyze the mechanism of conductivity variation.Compared with the unplasticized membranes,the ionic conductivity of the membrane with the addition of 35 wt.%PSi-PE was improved by 20 times.Meanwhile,the dielectric constant(ε)of the membrane was increased to 1330 and the relaxation time was decreased to 0.012 s.The changes of dielectric properties reflect directly the effect of PSi-PE on the dissociation ability of Liþand the chain segmental mobility,which well explains the reasons of ionic conductivity variation.
