Al^(3+)离子替代La_(0.67)Ca_(0.33)MnO_3体系的结构和输运行为研究

Study of structural and transport properties for Al^(3+)-doping La_(2/3)Ca_(1/3)MnO_3 perovsksite manganese

系统研究了Mn位替代的La0.67Ca0.33Mn1-xAlxO3体系的结构和输运特性。结果表明,随Al3+替代含量的增加,在整个替代范围内,晶胞体积表现出单调减小的规律。而体系的电阻率急剧增加,绝缘体 金属转变温度TIM向低温方向移动,且与Al3+替代含量存在线性关联。对少量Al3+替代含量,在T>TIM的高温区域体系的输运特性满足热激活模型,在T<TIM的低温区域满足金属输运行为。这种输运行为随Al3+替代的变化特征,可从Al3+离子对Mn3+—O2-—Mn4+双交换通道的破坏和所导致的晶格畸变方面给予解释,Al3+替代改变了电子的局域环境,进而影响到体系的输运行为。

The effects of Al^(3+) doping on Mn site have been studied for the colossal magnetoresistance material La_(0.67)Ca_(0.33)MnO_3. It was found that when doping amount of Al^(3+) increases the resistivity increase rapidly. The insulator-metal transition temperature move to lower temperature and decrease linearly with Al^(3+) doping. The crystal cell parameters decrease with Al^(3+) doping. At little Al doping, the resistance satisfy thermal active modal among T>T_(IM) and metal transport property among T<T_(IM). The double exchange channel of Mn^(3+)-O^(2-)-Mn^(4+) was jammed by doping Al^(3+) and bring crystal lattice aberrance, the local environment was changed and effected the transport property of system.