不同退火温度对球磨法制备La_(2/3)Ca_(1/3)MnO_3的微观结构和电磁输运行为的影响  

THE MICROSTRUCTURE AND ELECTRIC MAGNETIC TRANSPORTATION PROPERTIES OF MECHANICAL ALLOYED La_(2/3)Ca_(1/3)MnO_3 BY DIFFERENT ANNEALING TEMPERATURE

作　　者：麦远棠[1] 任忠明[1] 熊永红[1] 张炯[1] 皮厚礼[1] 魏立国[1] 熊曹水[1] 

机构地区：[1]华中科技大学物理系,武汉430074

出　　处：《低温物理学报》2006年第4期348-352,共5页Low Temperature Physical Letters

基　　金：国家自然科学基金(项目编号:10274022)资助的课题.~~

摘　　要：本文研究了在球磨法制备La2／3Ca1／3MnO3的过程中，不同退火温度对多晶陶瓷样品在微观结构和电磁输运行为方面的影响．结果表明，退火温度为850℃时，样品已经形成La2／3Ca1／3MnO3相；900℃以下，样品的晶粒为200～300nm，存在明显的晶界效应，在低温区出现明显的CMR效应；随退火温度升高，晶粒迅速长大至微米级，在1400℃退火时达4～51μm，表现出与固相反应法样品类似的性质，并且在金属-半导体转变温度附近出现较大的CMR峰值，在0．3T外场下达22％．Polycrystalline La2/3Ca1/3MnO3 was successfully synthesized by mechanical alloying, and the relation between the annealing temperature and the microstructure and the electric magnetic transportation properties was studied. Results shown that at the annealing temperature of 850℃, La2/3Ca1/3MnO3was synthesized and at 900℃, grain size was 200 - 300nm. Significant grain boundary effect existed, causing large MR at low temperature （78K）. When annealing temperature rise, grain grew much larger, up to 4 -51μm at 1400℃. Large CMR effect up to 22% at the applied field of 0.30T was observed around the metal-to-insulator transition.

关 键 词：稀土锰氧化物 球磨法 原子力显微镜 庞磁电阻效应 

分 类 号：O482.5[理学—固体物理]