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(1-x)La_(0.7)Ca_(0.3)MnO_3/xAg磁电阻的温度稳定性 被引量:2

Temperature Stability of Magnetoresistance in (1-x)La_(0.7)Ca_(0.3)MnO_3/xAg
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摘要 用固相反应法将Ag引入La0.7Ca0.3MnO3颗粒表面,形成(1-x)La0.7Ca0.3MnO3/xAg(x=0.00,0.10,0.20,0.25,0.30,0.35)。通过XRD谱、扫描电子显微镜(SEM)照片及SEM能谱(EDS)、ρ-T曲线、ρ-T拟合曲线、MR-T曲线,研究电输运性质及MR温度稳定性。结果表明:随复Ag量增大,电阻率急剧下降,高复Ag(x≥0.3)的电阻率比低复Ag(x≤0.10)的电阻率下降2个数量级;发现x=0.00,0.10用ρ-T2公式拟合比较合理,是单磁子散射作用;x=0.20,0.25用ρ-T2.5公式拟合比较合理,是自旋波散射作用;x=0.30,0.35,分别在97,93 K以上用ρ-T4.5公式拟合比较合理,说明是电子-磁子散射作用;所有复Ag样品,在250~20 K温区MR表现出很好的温度稳性,特别是x=0.10的样品,在220~150 K温区MR保持(13.8±0.2)%。提出磁电阻稳定性的机制:Ag与钙钛矿颗粒形成电输运二元通道,钙钛矿颗粒通道产生的低场磁电阻与Ag通道产生的正常磁电阻共同作用,产生MR温度稳定性。 Ag was introduced into the surface of La0.7 Ca0.3 MnO3 grains by the solid-state reaction method, and the samples ( 1 - x) La0.7Ca0.3MnO3/xAg (x =0. 00, 0.10, 0.20, 0.25, 0.30, 0.35) were prepared. The electric transport property and the temperature stability of MR in the system were studied through the measurements of XRD spectrum, scanning electron microscope (SEM) photo- graph and SEM spectroscopy (EDS), p-T curves p-T fitted curves, and MR-T curves. The results indicated that with the increase of composite Ag amount, resistivity decreased sharply, and the resistivity of the samples with high composite Ag amount ( x ≥0.3 ) was two orders of magnitude lower than that of the samples with low composite Ag amount(x≤0. 10) ; p-T curves of the samples of x = 0. 00, 0.10 could be reasonably fitted by the p-T2 formula, which belonged to single magneton scattering function; p-T curves of the samples of x = 0.20, 0.25 could be reasonably fitted by the p-T^2. 5 formula, which belonged to spin wave scattering function; p-T curves of the samples of x = 0.30, 0.35 could be reasonably fitted by the p-T^4 5 formula above 97 and 93 K respectively, which belonged to e- lectron-magneton scattering function; for all the samples with composite Ag, MR showed very good temperature stability in the tempera- ture range of 250 - 20 K, especially MR of the sample of x = 0.10 kept at ( 13.8 ± 0.2) % in the temperature range of 220 -150 K. The mechanism of magnetoresistance stability was put forward as below: Ag and the perovskite grains formed two channels for electric transport, and the temperature stability of MR came from the common effect of low-field magnetoresistance induced by the channel of perovskite grains and ordinary magnetoresistance induced by the channel of Ag.
出处 《稀有金属》 EI CAS CSCD 北大核心 2013年第1期49-54,共6页 Chinese Journal of Rare Metals
基金 国家自然科学基金重点项目(19934003) 安徽省教育厅自然科学研究重点项目(KJ2011A259 KJ2012Z404) 宿州学院教授(博士)基金项目(2011jb01 2011jb02) 宿州学院科研平台开放课题项目(2011YKF08)资助
关键词 磁电阻(MR) 温度稳定性 二相复合体 钙钛矿锰氧化物 magnetoresistance temperature stability two-phase composite perovskite manganite Ag
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