A La_(0.5)Ba_(0.5)MnO_(3-δ) oxide was prepared using the sol-gel technique.Instead of a pure phase,La_(0.5)Ba_(0.5)MnO_(3-δ) was discovered to be a combination of La_(0.7)Ba_(0.3)MnO_(3-δ) and BaMnO_(3).The in-situ...A La_(0.5)Ba_(0.5)MnO_(3-δ) oxide was prepared using the sol-gel technique.Instead of a pure phase,La_(0.5)Ba_(0.5)MnO_(3-δ) was discovered to be a combination of La_(0.7)Ba_(0.3)MnO_(3-δ) and BaMnO_(3).The in-situ production of La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites enhanced the oxygen vacancy(Vo)formation compared to single-phase La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3),providing potential benefits as a cathode for fuel cells.Subsequently,La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites were utilized as the cathode for proton-conducting solid oxide fuel cells(H-SOFCs),which significantly improved cell performance.At 700 C,H-SOFC with a La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposite cathode achieved the highest power density(1504 mW·cm^(-2))yet recorded for H-SOFCs with manganate cathodes.This performance was much greater than that of single-phase La_(0.7)Ba_(0.3)MnO_(3-δ)or BaMnO_(3) cathode cells.In addition,the cell demonstrated excellent working stability.First-principles calculations indicated that the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface was crucial for the enhanced cathode performance.The oxygen reduction reaction(ORR)free energy barrier was significantly lower at the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface than that at the La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3) surfaces,which explained the origin of high performance and gave a guide for the construction of novel cathodes for H-SOFCs.展开更多
Magnetoresistanoe in the temperature region from 300 K to liquid helium temperature has been measured on good (100) oriented La2/3Ca1/3MnO2 thin films prepared by d.c. magnetron sputtering on ZrO2 (100) substrates. It...Magnetoresistanoe in the temperature region from 300 K to liquid helium temperature has been measured on good (100) oriented La2/3Ca1/3MnO2 thin films prepared by d.c. magnetron sputtering on ZrO2 (100) substrates. It is found that there appears a resistance peak at about TP = 72K at zero magnetic field, and this peak moves to higher temperature with increasing field H, and R decreases simultaneously. However, the magnetoresistance ratio MR = 5R /R (H) = (Ro~ RH) /RH has a different temperature dependence. There are also MR peaks, but the temperature of maximum MR is at about 25 K which does not change with changing external magnetic field. The heat treatment (annealed at 700C in 105’Pa O2 for 30min) will make R reduce dramatically and has an effect on the temperature dependence of R and its MR.展开更多
Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(110) substrates by d. c. magnetron sputtering method. The measurements of magnetoresistance ρ(H) upon magnetic field at different temperatures were carried...Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(110) substrates by d. c. magnetron sputtering method. The measurements of magnetoresistance ρ(H) upon magnetic field at different temperatures were carried out in the field range of 0 - 8 T. It is found that p(H) obeys the following relations: when the temperature(T) is higher than the Curie temperature Tc, ρ ( H ) =1/α(T)+β(T)H2; below Tc, ρ ( H ) = ρ0 ( T ) 1/A(T)+B(T)exp(H/C(Y)),and ρ(H) =1/κa(T)+γ(T)H when T is far below TC. It is Suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductance.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52272216 and 51972183)the Hundred Youth Talents Program of Hunan,and the Startup Funding for Talents at University of South Chinathe support from the Hunan University Student Innovation and Entrepreneurship Training Program(Grant No.S202210555343)。
文摘A La_(0.5)Ba_(0.5)MnO_(3-δ) oxide was prepared using the sol-gel technique.Instead of a pure phase,La_(0.5)Ba_(0.5)MnO_(3-δ) was discovered to be a combination of La_(0.7)Ba_(0.3)MnO_(3-δ) and BaMnO_(3).The in-situ production of La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites enhanced the oxygen vacancy(Vo)formation compared to single-phase La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3),providing potential benefits as a cathode for fuel cells.Subsequently,La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposites were utilized as the cathode for proton-conducting solid oxide fuel cells(H-SOFCs),which significantly improved cell performance.At 700 C,H-SOFC with a La_(0.7)Ba_(0.3)MnO_(3-δ)+BaMnO_(3) nanocomposite cathode achieved the highest power density(1504 mW·cm^(-2))yet recorded for H-SOFCs with manganate cathodes.This performance was much greater than that of single-phase La_(0.7)Ba_(0.3)MnO_(3-δ)or BaMnO_(3) cathode cells.In addition,the cell demonstrated excellent working stability.First-principles calculations indicated that the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface was crucial for the enhanced cathode performance.The oxygen reduction reaction(ORR)free energy barrier was significantly lower at the La_(0.7)Ba_(0.3)MnO_(3-δ)/BaMnO_(3) interface than that at the La_(0.7)Ba_(0.3)MnO_(3-δ) or BaMnO_(3) surfaces,which explained the origin of high performance and gave a guide for the construction of novel cathodes for H-SOFCs.
基金supported by the National Natural Science Foundation of China (52272216 and 51972183)the Hundred Youth Talents Program of Hunan and the Startup Funding for Talents at the University of South China。
基金supported by the National Natural Science Foundation of China.
文摘Magnetoresistanoe in the temperature region from 300 K to liquid helium temperature has been measured on good (100) oriented La2/3Ca1/3MnO2 thin films prepared by d.c. magnetron sputtering on ZrO2 (100) substrates. It is found that there appears a resistance peak at about TP = 72K at zero magnetic field, and this peak moves to higher temperature with increasing field H, and R decreases simultaneously. However, the magnetoresistance ratio MR = 5R /R (H) = (Ro~ RH) /RH has a different temperature dependence. There are also MR peaks, but the temperature of maximum MR is at about 25 K which does not change with changing external magnetic field. The heat treatment (annealed at 700C in 105’Pa O2 for 30min) will make R reduce dramatically and has an effect on the temperature dependence of R and its MR.
基金Project supported by the National Natural Science Foundation of China (Grant No. 19504012) the Chinese Academy of Sciences
文摘Epitaxial La2/3Ca1/3 MnO3 thin films were prepared on NdGaO3(110) substrates by d. c. magnetron sputtering method. The measurements of magnetoresistance ρ(H) upon magnetic field at different temperatures were carried out in the field range of 0 - 8 T. It is found that p(H) obeys the following relations: when the temperature(T) is higher than the Curie temperature Tc, ρ ( H ) =1/α(T)+β(T)H2; below Tc, ρ ( H ) = ρ0 ( T ) 1/A(T)+B(T)exp(H/C(Y)),and ρ(H) =1/κa(T)+γ(T)H when T is far below TC. It is Suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductance.
