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首页> 外文期刊>Physica, B. Condensed Matter >Magnetoresistive studies on nanocrystalline La0.8Sr0.2MnO3+delta manganite
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Magnetoresistive studies on nanocrystalline La0.8Sr0.2MnO3+delta manganite

机译：纳米晶La0.8Sr0.2MnO3 +δ锰铁矿的磁阻研究

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摘要

Low-temperature magnetoresistance (MR) measurement has been carried out on nanocrystalline La0.8Sr0.2MnO3+delta manganites prepared by combustion synthesis. This preparation method yields voluminous powders with large surface area (similar to 40 m(2)/g) having crystalline nanosize (similar to 50 nm) products. Formation and homogeneity of the solid solutions have been confirmed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Rietveld refinement of X-ray data indicates that as-formed compound exhibits cubic phase with space group Pm3 m. However, calcined sample transforms into rhombohedral phase with space group R-3c. The stabilization of the cubic phase in as-formed manganite is due to the substitution of Sr2+ on La3+ sites, resulting in higher Mn4+ content. The low-temperature resistivity measurements down to 70 K exhibit a broad metal-insulator transition (TM-I) at around 257 K. MR measurements on sintered pellets show similar to 5% MR at 1 T, whereas for 4 and 7 T, the %MR values are found as 22% and 28%. respectively, at TM-I.
机译：已经对通过燃烧合成制备的纳米晶La0.8Sr0.2MnO3 +δ锰矿进行了低温磁阻（MR）测量。该制备方法产生具有结晶纳米尺寸（类似于50nm）产物的大表面积（类似于40m（2）/ g）的大体积粉末。固溶体的形成和均匀性已通过粉末X射线衍射（PXRD），扫描电子显微镜（SEM）和能量分散光谱（EDS）得以确认。 X射线数据的Rietveld精炼表明，所形成的化合物显示立方相，空间群为Pm3 m。但是，煅烧后的样品会变成带有空间群R-3c的菱面体相。形成的锰矿中立方相的稳定是由于La3 +位置上Sr2 +的取代，导致Mn4 +含量更高。低至70 K的低温电阻率测量值在257 K左右显示出较宽的金属-绝缘体转变（TM-I）。烧结球团的MR测量在1 T时显示出接近5％MR，而对于4 T和7 T，发现％MR值是22％和28％。分别在TM-1。

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