烧结温度对钙钛矿锰氧化物颗粒表面覆Ag的二相复合体系磁电阻的影响

Influence of Sintering Temperature on Magnetoresistance In the Two-phase Composite System ofPerovskite Manganite with Ag Covering Its Grain Surface

用固相反应法采用不同烧结温度,制备二相复合体系。分别选用La0.6Dy0.1Sr0.3MnO3和La0.5Sm0.2Sr0.3MnO3为母体,与金属Ag复合,研究不同烧结温度对二相复合体系磁电阻增强效应的影响。结果表明:不同烧结温度对二相复合体系磁电阻增强效应的影响很大,烧结温度低,磁电阻增强效应明显。在制作钙钛矿锰氧化物母体时,只要能形成单相结构,烧结温度越低越好。烧结温度越低,颗粒越小,界面越多;Ag与钙钛矿锰氧化物母体复合时,烧结温度也不要高。只要能满足压片所需烧结温度,烧结温度低有利于钙钛矿锰氧化物颗粒表面覆Ag。

A two-phase composite system was prepared at different sintering temperatures by the solid-state reaction method. La0.6Dy0.1Sr0.3MnO3 and La0.5Sm0.2Sr0.3MnO3 were chosen as the matrix and were compounded with metallic Ag, then the influences of different sintering temperatures on the enhancemenl of magnetore- sistance in the two-phase composite system were studied. The results indicate that： different sintering tempera- tures have great influences on the enhancement of magnetoresistance in the two-phase composite system,and the enhancement of magnetoresistance is more apparent when the sintering temperature is lower. As long as the matrix of the perovskite manganite can form single-phase structure, the sintering temperature should be as low as possible. The lower is the sintering temperature, the smaller are the grains, and the more are the bound- aries; when Ag is compounded with the matrix of the perovskite manganite, the sintering temperature also shouldn＇t be high because low sintering temperature is good for the grain surface of the perovskite manganite to be covered by Ag.