La_(0.5-x)Ce_xBa_(0.5)CoO_3化合物的磁性和输运特性

Magnetic and Transport Properties of La_(0.5-x) Ce_xBa_(0.5) CoO_3 Compounds

在La0 5 Ba0 5 CoO3 中 ,系统研究了Ce对La的替代效应。Ce的掺入首先产生了电荷转移效应。材料高温磁化率测量表明 ,每个Ce原子向Co的 3d壳层转移 2 86个电子 ,结果随Ce掺入量增加 ,材料磁矩成线性下降。另外 ,随Ce含量增加 ,材料居里温度单调下降 ,这是由于稀土离子的尺寸效应。在所研究的温度范围内 ,所有材料的导电机理都属于极化子的变程跳跃导电。由于电荷转移效应 ,使材料电阻率随Ce掺入量增加而迅速加大。当La全部被Ce替代后 。

Substitution effects of Ce for La in La 0.5 Ba 0.5 CoO\-3 have been studied systematically.Doping of Ce induces the charge transfer effect.The measurements of high temperature susceptibilities of the materials showed that each Ce atom transfers 2\^86 electrons to the 3d orbital of Co atoms.As a result,the magnetic moment of materials decreases linearly with increasing the Ce content.On the other hand,with the increase of Ce content the Curie temperature decreases monotonically.This is due to the size effect of the rear earth ions.In the investigated temperature range,the conductive mechanism ofr all samples belongs to the variable range hopping conduction of the polarons.Due to the charge transfer,the electrical resistivities of the materials increase remarkably with increasing the Ce content.When all La atoms are substituted by Ce, the resistivity of the materials at room temperature increases by over five orders of magnitude.