Samples of manganese oxides La（1-x）2/3Ca1/3MnO3（x 〈 0.10） with Lavacancy were prepared by standard solid-state reaction method. All the samples are single phase, with orthorhombic symmetry （Pnma ）, analyzed by ...Samples of manganese oxides La（1-x）2/3Ca1/3MnO3（x 〈 0.10） with Lavacancy were prepared by standard solid-state reaction method. All the samples are single phase, with orthorhombic symmetry （Pnma ）, analyzed by XRD and with Rietveld Refinement. The effect of different La-site vacancies concentration on electronic transport of La（1-x）2/3Ca1/3MnO3 was investigated. The insulator-metal transition temperature （about 267 K） nearly remains unchanged with the increase of vacancy concentration, which indicates that small La-vacancy does not destroy the double exchange interaction. But the electronic resistance increases and MR value decreases with La-vacancy content x 〉 0.04. The maximum of the MR value （8 T） is about 220% at transition temperature （TMI）.展开更多
In this work, the enthalpy of fusion and melting points of 2-（tert-butyl）-5-methylphenol （2B5MP） and 2-（tert-butyl）-4-methylphenol （2B4MP） were measured by differential scanning calorimetry （DSC）. The binary...In this work, the enthalpy of fusion and melting points of 2-（tert-butyl）-5-methylphenol （2B5MP） and 2-（tert-butyl）-4-methylphenol （2B4MP） were measured by differential scanning calorimetry （DSC）. The binary solid-liquid equilibrium （SLE） of both compounds were predicted by integrated computer aided system （ICAS） and measured by DSC. The corresponding eutectic molar composition is 0.6998 and the eutectic temperature is 281.96 K. The quasi-static heat capacities of 2B5MP and 2B4MP were evaluated by stochastic temperature modulation DSC technique （TOPEM）. The SLE experimental data were correlated using the Margules, Wilson, and non-random two liquid （NRTL） equations and a good agreement between measurement and calculation could be obtained.展开更多
文摘Samples of manganese oxides La（1-x）2/3Ca1/3MnO3（x 〈 0.10） with Lavacancy were prepared by standard solid-state reaction method. All the samples are single phase, with orthorhombic symmetry （Pnma ）, analyzed by XRD and with Rietveld Refinement. The effect of different La-site vacancies concentration on electronic transport of La（1-x）2/3Ca1/3MnO3 was investigated. The insulator-metal transition temperature （about 267 K） nearly remains unchanged with the increase of vacancy concentration, which indicates that small La-vacancy does not destroy the double exchange interaction. But the electronic resistance increases and MR value decreases with La-vacancy content x 〉 0.04. The maximum of the MR value （8 T） is about 220% at transition temperature （TMI）.
基金We are grateful to Prof. Rafiqul Gani for providing the software ICAS. This work was financially supported by the National Natural Science Foundation of China （Grant Nos. 20836005, 21003077 and 21176184） and Open Project of Key Laboratory Advanced Energy Materials Chemistry （Nankai University） （KLAEMC-OP201201）.
文摘In this work, the enthalpy of fusion and melting points of 2-（tert-butyl）-5-methylphenol （2B5MP） and 2-（tert-butyl）-4-methylphenol （2B4MP） were measured by differential scanning calorimetry （DSC）. The binary solid-liquid equilibrium （SLE） of both compounds were predicted by integrated computer aided system （ICAS） and measured by DSC. The corresponding eutectic molar composition is 0.6998 and the eutectic temperature is 281.96 K. The quasi-static heat capacities of 2B5MP and 2B4MP were evaluated by stochastic temperature modulation DSC technique （TOPEM）. The SLE experimental data were correlated using the Margules, Wilson, and non-random two liquid （NRTL） equations and a good agreement between measurement and calculation could be obtained.
