用固相反应法制备La0.5Sm0.2Sr0.3MnO3/(Ag2O)x/2(x=0.00,0.04,0.08,0.25,0.30)样品,通过M～T曲线,P～T曲线,P～T拟合曲线,研究样品的磁性质、输运行为、输运机制及磁电阻效应.结果表明:少量掺杂时Ag可能参与反应.掺杂量较多时,Ag主要以金属态分离到母体颗粒的界面处,使体系形成两相复合体,少量的Ag掺杂可以明显提高自旋相关散射产生的晶界磁电阻,掺Ag为30%摩尔比时,样品的电阻率较低掺杂样品的电阻率降低一个数量级,在300K、0.5T磁场下,磁电阻明显增强,达到9.4%,这与颗粒母体界面结构的改善有关,也与材料电阻率的降低有关.
La0.5Sm0.2Sr0.3MnO3/(Ag2O)x/2(x =0.00,0.04,0.08,0.25,0.30) samples were prepared by the solid-state reaction method, and their magnetic proverties ,transport behavior, transport mechanism and magnetoresistanee effect were studied through M ～ T curves measuring ,p ～ T curves measuring and fitting. The results showed that: Ag may take part in reaction when the doping amount is small. Ag is mainly distributed at the grain boundary of the mother body and is in metallic state when the doping amount is relatively large, then the system becomes a two-phase composite. A small a-mount of Ag doping can apparently increase grain-boundary magnetoresistance induced by spin-dependent scattering. The resistivity of the sample doped with 30mol. % Ag is one order of magnitude smaller than that of low-doped samples, and its magnetoresistanee in the magnetic field of 0.5T and at 300K strengthens apparendy and reach 9.4%, which is connected not only with the improvement of grain-boundary structure of the mother body but also with the decrease of material resistivi-ty.
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