利用氩离子束镀膜技术在 Si O2 / Si衬底上淀积钛酸镧锶 (Sr1 - x L ax Ti O3)膜 ,并制成平面型电阻器。研究了薄膜电阻器的光电流与照度、电压和电极间距的关系以及薄膜在调制光下的频率特性 ,计算出薄膜中载流子寿命约为 2 9ms。结果...利用氩离子束镀膜技术在 Si O2 / Si衬底上淀积钛酸镧锶 (Sr1 - x L ax Ti O3)膜 ,并制成平面型电阻器。研究了薄膜电阻器的光电流与照度、电压和电极间距的关系以及薄膜在调制光下的频率特性 ,计算出薄膜中载流子寿命约为 2 9ms。结果表明 ,Sr1 - x L ax Ti O3薄膜在可见光区域具有较好的光敏特性 ,其灵敏度和光电导增益都比较高。在弱照度下 ,光电流随照度变化较快 ,主要与单分子复合过程相关 ;而在强照度下 ,变化趋于缓慢 。展开更多
Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the M...Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn-O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.展开更多
The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnet...The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenological formula of ρ(T)=(1σ(T)= (1α(M/M s) 2+βexp(-E 0/k BT), where the fitting parameters α,β vary as the external magnetic field H changes, E 0 is the activation energy, E 0/k B =1160 K, M s is the saturation magnetization, the temperature and magnetic field dependence of M/M s is obtained by the mean-field expression.展开更多
As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to...As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to explore the intrinsic mechanism of oxygen evolution reaction(OER)using two-dimensional thin film La1-xSrxCoO3 electrode as a model.Herein,we report a planar two-dimensional model La1-xSrxCoO3 electrode grown on a Nb-SrTiO3 single-crystal substrate via pulsed laser deposition.The two-dimensional La1-xSrxCoO3 films offer different oxygen evolution activities at different pH electrolyte solutions.The mechanisms behind the variations of the oxygen evolution activity were discussed after comparing the oxygen evolution activity before and after treatments of the electrodes and measurements by various test methods.The results of this study offer a promising,low-cost electrode material for the efficient OER and a sustainable production of hydrogen fuel.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
文摘利用氩离子束镀膜技术在 Si O2 / Si衬底上淀积钛酸镧锶 (Sr1 - x L ax Ti O3)膜 ,并制成平面型电阻器。研究了薄膜电阻器的光电流与照度、电压和电极间距的关系以及薄膜在调制光下的频率特性 ,计算出薄膜中载流子寿命约为 2 9ms。结果表明 ,Sr1 - x L ax Ti O3薄膜在可见光区域具有较好的光敏特性 ,其灵敏度和光电导增益都比较高。在弱照度下 ,光电流随照度变化较快 ,主要与单分子复合过程相关 ;而在强照度下 ,变化趋于缓慢 。
基金Supported by the National Natural Science Foundation of China under Grant Nos G50225209 and G50271023, the Key Foundation of Education Ministry of China under Grant G02017 and the Natural Science Foundation of Hebei Province under Grant No G503031.
文摘Infrared absorption spectra of La0.67-xPrxCa0.33MnO3 （x= 0, 0.18 and 0.36） are experimentally studied in the temperature range 20 -300K. Absorption peak splitting corresponding to the stretching oscillation of the Mn-O bond, together with a shift of peak position, is observed below the Curie temperature. These features weaken and even disappear as the samples are warmed up to the Curie temperature, which indicates that this anomaly may be a result of phase separation in the compounds.
文摘The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77-300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenological formula of ρ(T)=(1σ(T)= (1α(M/M s) 2+βexp(-E 0/k BT), where the fitting parameters α,β vary as the external magnetic field H changes, E 0 is the activation energy, E 0/k B =1160 K, M s is the saturation magnetization, the temperature and magnetic field dependence of M/M s is obtained by the mean-field expression.
基金the National Natural Science Foundation of China(Grant Nos.11574365,and 11974099)the Program for the Innovation Team of Science and Technology in University of Henan(Grant No.20IRTSTHN014)。
文摘As an alternative electrode material,transition metal oxides are promising candidates due to multivalent nature and oxygen vacancies present in the structure with facilitate redox reactions.The aim of this study is to explore the intrinsic mechanism of oxygen evolution reaction(OER)using two-dimensional thin film La1-xSrxCoO3 electrode as a model.Herein,we report a planar two-dimensional model La1-xSrxCoO3 electrode grown on a Nb-SrTiO3 single-crystal substrate via pulsed laser deposition.The two-dimensional La1-xSrxCoO3 films offer different oxygen evolution activities at different pH electrolyte solutions.The mechanisms behind the variations of the oxygen evolution activity were discussed after comparing the oxygen evolution activity before and after treatments of the electrodes and measurements by various test methods.The results of this study offer a promising,low-cost electrode material for the efficient OER and a sustainable production of hydrogen fuel.
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.
