【摘要】 将La0.67Sr0.33MnO3,Ag2O及TiO2粉混合经高温烧结后制备了两个系列钙钛矿相与金属Ag相的复合体系,通过改变Ti及Ag在样品中的含量,比较研究了材料的输运特性。0.07摩尔比Ti4+离子的掺杂能有效地把居里温度降至室温,而Ag的掺杂使材料的导电性明显增强。在顺磁高温区,材料的电导满足极化子跃迁机制,说明该复合体系中钙钛矿材料仍是系统的主要导电通道。室温下从Ag摩尔比x=0.30样品中得到最大的磁电阻,约为32%,是La0.67Sr0.33MnO3样品的8倍,也是未掺Ag样品的1.6倍。结果表明,采用Ag复合方法是提高钙钛矿材料室温磁电阻的有效手段。更多还原

【Abstract】 Two series composites of La0.67Sr0.33MnO3+0.07TiO2+xAg and La0.67Sr0.33MnO3+0.08TiO2+xAg were prepared by calcining the mixture of manganite,TiO2 and Ag2O powders.And the corresponding transport properties were also investigated.The Curie temperature successfully lowers to room temperature with addition of 0.07 mol ratio Ti4+.Ag addition remarkably enhanced the low-field magnetoresistance at room temperature.The resistivity followed the adiabatic polaron hopping mechanism in the semiconductor regime(T>TP),indicating that the current path through the granular perovskite was still the main conductive path.A maximum MR ratio of 32% at room temperature was obtained for the samples with x=0.30,which was approximately 8 times and 1.6 times as large as that for La0.67Sr0.33MnO3 and La0.67Sr0.33MnO3+0.07TiO2,respectively.These results indicated that the introducing Ag into perovskite was an effective selection in enhancement of MR at room temperature.更多还原