La_(0.85)Na_(0.15)MnO_3的结构、磁性质和输运性质

STRUCTURE,MAGNETIC AND TRANSPORT PROPERTIES OF La_(0.85)Na_(0.15)MnO_3 CERAMICS

实验研究了由 Pechini方法制备的 L a0 .85Na0 .1 5Mn O3多晶陶瓷样品的结构、磁性质和输运性质 .发现 L a0 .85Na0 .1 5Mn O3的居里温度正好接近室温 ,在该温度附近 ,伴随铁磁相到顺磁相的转变 ,同时发生金属 -半导体转变 ,且在居里温度附近 ,0 .5 T外磁场下的最大磁电阻可达 14 % .理论与实验对比可知 ,在居里温度以上小极化子非对角跳跃为主要导电机制 .

Polycrystalline La 0.85 Na 0.15 MnO 3 ceramics were prepared by Pechini process and their structure,magnetic and transport properties have been investigated.The Curie temperature,at which a transition from metallic to semiconducting occurs along with the transition from ferromagnetic to paramagnetic,is just in the vicinity of room temperature.In addition,a low field magnetoresistance about 14% at 0.5 T was observed near the Curie temperature.The small polaron hopping is considered to be the main transport mechanism above the Curie temperature by comparing the experimental data with the theoretical results.