空位掺杂La_((1-x)2/3)Ca_(1/3)MnO_3的结构及磁电阻效应  

Structural and Magnetoresistance Effect of La_((1-x)2/3)Ca_(1/3)MnO_3 with Vacancies

作　　者：罗广圣[1] 辛勇[2] 胡凌燕[3] 雷宇[1] 刘光华[1] 周正有[1] 陈光[4] 甘建萍[1] 欧阳小吕[1] 

机构地区：[1]南昌大学材料科学与工程学院,江西南昌330031 [2]南昌大学理学院,江西南昌330031 [3]南昌大学信息工程学院,江西南昌330031 [4]南昌大学科技学院,江西南昌330047

出　　处：《南昌大学学报（工科版）》2007年第4期331-335,共5页Journal of Nanchang University(Engineering & Technology)

基　　金：江西省教育厅科技计划资助项目(赣教技字[2006]25号);南昌大学科学基金资助项目(Z-03694);江西省高等学校教学改革研究省级课题(JXJG-06-1-30);南京大学固体微结构物理国家重点实验室基金资助项目(M041916)

摘　　要：利用标准的固相反应法在1200℃烧结了La(1-x)2/3Ca1/3MnO3(x=0,0.02,0.04,0.08,0.10)样品,冷却后,取出部分在1350℃进行再烧结。利用X射线衍射(XRD)和扫描电镜(SEM)对其晶体结构及表面微观结构进行了研究。X射线衍射测量分析表明样品均为单相,单胞仍然具有正交对称性结构(空间群为Pnm a),随着掺杂浓度的增加,晶格常数和晶胞体积逐渐减小。通过扫描电镜研究表明,样品随着掺杂浓度增加,晶粒逐渐增大,均匀性变好;样品在1350℃再烧结条件下,平均粒度要大,空隙度变小。样品随着掺杂浓度的增加,电阻在逐渐增大,磁电阻在逐渐减小。Some La-Vacancy samples of La（l-x）2/3 Ca1/3 MnO3 （x=0,0.02,0.04,0.08,0.10） were prepared by solid-state reaction method at 1200 ℃. Then we selected part of the samples to resinter at 1 350 ℃. The crystal structures and surface morphologies of the La-site vacancies compounds were studied by X-Ray Diffraction （XRD） and Scanning electron microscope （SEM）. The results by XRD showed that all the samples were single phase with orthorhombic symmetry （Pnma） and the lattice parameters and unit-ceall volume varied with different La-vacancy concentration. The results by SEM showed that the crystal grain size increased after resintered at 1 350 ℃. The re-sistance increased but the magnetoresistance decreased with the increase of La-vacancy concentration.

关 键 词：La(1-x)2/3Ca1/3MnO3 晶体结构 微观机制 磁电阻效应 

分 类 号：O307[理学—力学]