La0.5Ba0.5CoO3中的Pr掺杂效应

用固相反应法制备了La0.5-xPrxBa0.5CoO3系列化合物，系统研究了Pr不同含量时材料的磁性和电输运特性，结果表明：Pr掺杂没有改变Co的3d电子的巡游特性。随Pr掺杂量增加，材料的分子磁矩单调下降，其原因是当Pr逐渐取代La时，Co离子的3d电子逐渐由中间自旋态向低自放态转变。随Pr含量增加，材料的居里温度逐渐下降，这是由于稀土离子的尺寸效应，电阻测量表明：在所研究的温度范围内，居里温度以下，所有掺Pr材料的导电机制为热扩散型。居里点以上，导电机制为变程跳跃导电。

Effects of Pr doping in La0.5- xPrxBa0.5CoO3

La 0.5-x Pr x Ba 0.5 CoO 3 Compounds were prepared by the solid state reaction.Magnetic and transport properties of the materia ls with different Pr content were stu died systematically.The results show that substitution of Pr does not change the itinerant properties of t he 3d electrons of Co.The molecular moment of the materials decreases with Pr content increasing m onotonically,because the spin state of Co ions in the samples tr ansits from intermediate to low spin state gradually.The Curie temperature of the materials decrea ses with Pr content increasing,due t o the size effect of the rear -earth ions.The electric resistance measurements show that,for all the d oped materials in tested tem -perature range,below Curie tempera ture,the conductive mechanism of th e materials belongs to the thermal diffusion;and over Curie te mperature,it becomes variable -ran ge hopping mode.