LaMnO_3的La位掺杂对输运特性和磁电阻的影响  

Influence on Transport Properties and Magnetoresistance of Different Element Substitution in La-site of LaMnO_3

作　　者：周振春[1] 

机构地区：[1]丽水学院数理学院,浙江丽水323000

出　　处：《丽水学院学报》2005年第5期46-51,共6页Journal of Lishui University

基　　金：国家自然科学基金资助项目(10274070)

摘　　要：采用固相反应法制备实验所需的多晶样品,主要探讨LaMnO3的La位分别用不同价阳离子掺杂对输运特性和磁电阻的影响,明确指出La位掺杂是提高和调制钙钛矿型锰氧化物超大磁电阻(CMR)效应的一种有效途径。实验结果表明:La1-xMxMnO3(M为Ag,Na)多晶样品当0.1<x<0.2时室温磁电阻值最大;La1-xMxMnO3(M为Sr,Ca,Pb等)当x=0.33时体系为最佳导电和CMR态,其本质原因是双交换(DE)作用和Jahn-Teller效应;La1-xMxMnO3(M为Te,Ce,Zr,Sb等)电子掺杂型锰氧化物在发生PM-FM转变的同时伴随半导体-金属的相变,而两个相变温度Tc与Tp非常接近,在Tc附近具有CMR效应,这种现象我们认为可用广义的DE模型来解释。Polycrystalline samples were prepared successfully by solid - state reaction, and the influence on transport properties and magnetoresistance of different elements substitution in La - site of LaMnO3 was investigated; We clearly point out that the substitution in La - site is an efficient method for promoting and modulating the CMR effect of perovskite manganite. The experimental results show that the magnetoresistance under room temperature of polycrystalline samples La1-xMxMnO3（M = Ag, Na） get maximum when 0.1 〈 x 〈 0.2 ; the most optimal electrical properties and CMR of La1 - x Mx MnO3 （ M = Sr, Ca, Pb） are obtained when x = 0.33 and its essential factor is double exchange（DE） interaction and Jahn-Teller effect; a paramagnetic- ferromagnetic transition accompanying with a metal - semiconductor phase transition is found for the eledtron - doped Manganites La1-xMxMnO3（M = Te, Ce, Zr, Sb）, moreover the Tc is close to Tp and CMR effect is found around To, we suppose that this phenomena can be explained by generalized DE model.

关 键 词：钙钛矿型 La位掺杂 双交换(DE)作用 Curie温度(Tc) CMR效应 

分 类 号：O513[理学—低温物理]