摘要
Several samples of manganese oxides La(1-x)2/3Ca1/3MnO3 (V-LCMO) and (La0.7-xY0.3)2/3Ca1/3MnO3 (x<0.15) (V-LYCMO) with vacancies at La-site (La-vacancy) were prepared by solid-state reaction method. The X-ray diffraction(XRD) patterns refined by Rietveld confirm that these compounds exhibit single phase structure with orthorhombic symmetry (Pnma). The lattice parameters, Mn—O bond length and Mn—O—Mn bond angle vary with La-vacancy concentration, as an indication of the occurrence of the local Jahn-Teller effect. The measurement result of V-LCMO compounds shows that the maximum magnetoresistance(MR) is about 220% at TIM=268 K and La-vacancy content x=0.04. For V-LYCMO compounds, there exists metal-insulator transition at about 50 K, and a very large MR (over 106%) is observed at the temperature ranging from 40 K to 50 K.
Several samples of manganese oxides La(1-x)2/3Cal/3MnO3 (V-LCMO) and (La0.7-xY0.3)2/3Cal/3MnO3 (x〈0.15) (V-LYCMO) with vacancies at La-site (La-vacancy) were prepared by solid-state reaction method. The X-ray diffraction(XRD) patterns refined by Rietveld confirm that these compounds exhibit single phase structure with orthorhombic symmetry (Pnma). The lattice parameters, Mn-O bond length and Mn—O—Mn bond angle vary with La-vacancy concentration, as an indication of the occurrence of the local Jahn-Teller effect. The measurement result of V-LCMO compounds shows that the maximum magnetoresistance(MR) is about 220% at TIM=268 K and La-vacancy content x=0.04. For V-LYCMO compounds, there exists metal-insulator transition at about 50 K, and a very large MR (over 106%) is observed at the temperature ranging from 40 K to 50 K.
出处
《中国有色金属学会会刊:英文版》
CSCD
2007年第5期992-995,共4页
Transactions of Nonferrous Metals Society of China
基金
Project(0150014) supported by the Natural Science Foundation of Jiangxi Province, China