As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the or...As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the orthorhombic perovskite GdFeO 3 type. XPS analysis indicates that chrome ions are in different valence state. The introduction of Ca 2+ into the lattice induces the oxidation of Cr 3+ to Cr 6+ . With x increasing, the amount of Cr 6+ increases. The present of the more Cr 6+ is one of the important factors that effect electric conductivity of La 1-x Ca x CrO 3.展开更多
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
文摘As an interconnector of solid oxide fuel cell, La 1-x Ca x CrO 3( x =0 0~0 5) were prepared by sol gel method. The crystal structures of La 1-x Ca x CrO 3 at room temperature are the orthorhombic perovskite GdFeO 3 type. XPS analysis indicates that chrome ions are in different valence state. The introduction of Ca 2+ into the lattice induces the oxidation of Cr 3+ to Cr 6+ . With x increasing, the amount of Cr 6+ increases. The present of the more Cr 6+ is one of the important factors that effect electric conductivity of La 1-x Ca x CrO 3.
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).