不同烧结温度的La_(0.8)Sr_(0.05)Na_(0.15)MnO_3电输运性质及磁电阻的温度稳定性  

INFLUENCE OF DIFFERENT SINTERING TEMPERATURE ON ELECTRIC TRANSPORT PROPERTY AND THERMAL STABILITY OF MAGNETORESISTANCE OF THE La_(0.8)Sr_(0.05)Na_(0.15)MnO_3

作　　者：杨杰[1,2] 唐永刚[1,2] 王桂英[1,2] 毛强[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》2013年第3期187-191,共5页Low Temperature Physical Letters

基　　金：国家自然科学基金重点项目(批准号:19934003);安徽省教育厅自然科学研究重点项目(批准号:KJ2011A259);安徽省教育厅自然科学研究项目(批准号:KJ2012Z404);自旋电子与纳米材料安徽省重点实验室培育基地开放课题(2012YKF07;2012YKF08)资助的课题~~

摘　　要：用固相反应法制备La0.8Sr0.05Na0.15MnO3多晶样品,通过X射线衍射(XRD)图谱、扫描电镜(SEM)照片、电阻率-温度(ρ～T)曲线、磁电阻-温度(MR～T)曲线,研究不同烧结温度对La0.8Sr0.05Na0.15MnO3电输运性质的影响及磁电阻的温度稳定性.研究结果表明:钙钛矿氧化物多晶样品形成体相和表面相,体相的电输运由双交换作用支配,表面相的电输运是自旋相关散射或自旋极化隧穿,电输运性质由二次颗粒大小及二次颗粒周边环境决定.体相产生的本征磁电阻在高温区占优势,表面相产生的磁电阻在低温区占优势,二者迭加在某一温区产生磁电阻的温度稳定性.烧结温度为1100℃(Ts1100)的样品,0.8T磁场下,在320～243K温区,磁电阻保持(9.2±0.2)%基本不变,实现了在室温附近较大温区(△T=77K)磁电阻的温度稳定性.La0.8Sr0.05Na0.15MnO3 samples were prepared by solid-state reaction, and the influence of different sintering temperature on electric transport property and thermal stability of magnetoresistance of the samples were studied through the measurements of x-ray diffraction （XRD） patterns, scanning electron microscope （SEM） images, resistivity-temperature （ρ-T） curves, and magnetoresistance-temperature （MR-T） curves. The results indicate that polycrystalline La0.8Sr0.05Na0.15MnO3 samples have bulk phase and surface phase. The electric transport of bulk phase is induced by double-exehange function, and electric transport of the surface phase is induced by spin-dependent scattering or spin polarization tunneling. The electric transport properties are determined by the size of secondary particles and the surrounding environment of secondary particles. The intrinsic magnetoresistance in bulk phase predominates at high temperature zone, and magnetoresistance of the surface phase predominates at low temperature zone. However, temperature stability of magnetoresistanee can be made by superimposing between bulk and surface phases at a temperature zone. For sintering at 1100℃ （Ts1100）, the magnetoresistance is hardly changed in the temperature range of 320 - 243 K under magnetic field of 0. 8 T conditions, which leads to temperature stability of magnetoresistanee in the wider temperature range（AT= 77 K）near room temperature.

关 键 词：钙钛矿锰氧化物 电输运性质 磁电阻温度稳定性 烧结温度 

分 类 号：O482.4[理学—固体物理]