Ag和K掺杂对La_(4/5)Sr_(1/5)MnO_3电输运性质及磁电阻的影响  

INFLUENCE OF Ag AND K DOPINGS ON ELECTRIC TRANSPORT PROPERTY AND MAGNETORSISTANCE OF La_(4/5)Sr_(1/5)MnO_3

作　　者：张明玉[1,2] 严国清[1,2] 唐永刚[1,2] 王桂英[1,2] 宋启祥[1,2] 彭振生[1] 

机构地区：[1]自旋电子与纳米材料安徽省重点实验室（培育基地）,安徽宿州234000 [2]宿州学院机械与电子工程学院,安徽宿州234000

出　　处：《低温物理学报》2012年第3期200-204,共5页Low Temperature Physical Letters

基　　金：安徽省教育厅自然科学研究重点项目(批准号:KJ2011A259);宿州学院教授(博士)基金项目(批准号:2011jb01;2011jb02)资助的课题;Project supported by the Key Program of National Natural Science Foundation of China(Grant No.19934003)~~

摘　　要：用固相反应法制备La4/5Sr1/5MnO3及在其A位分别掺K、Ag系列样品,通过X射线衍射(XRD)谱,电阻率-温度(ρ～T)曲线,磁电阻-温度(MR～T)曲线,研究了在A位同时掺入一价、二价元素而保持Mn3+/Mn4+比值(摩尔比n(A)/n(B))不变的钙钛矿锰氧化物体系A位离子半径<rA>及A位离子的无序度σ2对电输运性质及磁电阻的影响.结果表明:A位离子的无序度σ2对电输运性质的影响比A位平均离子半径<rA>对电输运性质的影响大;电阻率曲线出现双峰是由于表面相电阻率与体相电阻率竞争的结果;MR的温度稳定性是本征磁电阻与隧穿磁电阻竞争的结果;掺K样品在253～175K温区MR从8.1%缓慢上升到9.5%,掺Ag样品在260K以下温区MR都在7.4%以上,纯的La4/5Sr1/5MnO3样品在318～259K温区MR都在7.0%以上,在如此宽温区MR几乎不变有利于MR的实际应用.La4/5 Srl/5 MnO3 and its doped samples with respective doping of K and Ag at A-site were prepared by the solid-state reaction method. The influences of the radius 〈rA〉 and disorder degree a2 of A-site ions on electric transport property and magnetoresistance of the perovskite manganite system with unchanged value of Mn3＋/Mn4＋ ratio through the introduction of both univalent and bivalent elements at A-site have been studied through the measurements of X-ray diffraction （XRD） patterns, resistivity-temperature （MR-T） curves, and magnetoresistance-temperature （MR-T） curves. The results indicate that： the influence of the disorder degreea2 of A-site ions on electric transport property is larger than that of the average radius 〈rA 〉 of A-site ions; the resistivity curves exhibit the double-peak phenomenon, which is the result of the competition between the resistivity of surface phase and that of body phase; the temperature stability of MR is the result of the competition between intrinsic magnetoresistance and tunneling magnetoresistance; MR of the sample with K doping increases slowly from 8. 1 ~ to 9.5 % in the tempera- ture range of 253-175 K, MR of the sample with Ag doping is above 7. 4% in the temperature range below 260 K, and MR of the pure sample La4/5 Sr1/5 MnO3 is above 7.0% in the temperature range of 318-259 K; MR almost keeps the same in such wide temperature range, which is beneficial to its practical application.

关 键 词：电输运性质 磁电阻 A位离子半径 无序度 钙钛矿锰氧化物 

分 类 号：O482.5[理学—固体物理]