【摘要】 研究了Al离子的Mn位替代对巨磁阻材料La0.67Ca0.33MnO3体系的结构和输运特性的影响。结果表明,随Al3+替代量的增加,在整个替代范围内,晶胞体积表现出单调减小的规律。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+替代量存在线性关联。对少量Al3+替代量,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+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。更多还原

【Abstract】 The effects of Al ion doping on Mn site were studied for the colossal magnetoresistance material La_0.67Ca_0.33MnO₃. It is found that when Al-doping amount x increases the crystal cell volume decreases monotonically in all range of doping. Resistances of system increase rapidly and the insulator-metal transition temperature T_IM moves to lower temperature and decreases linearly with Al-doping amount x. At small amount of Al-doping, the resistances satisfy thermal active model in the range of T>T_IM and metal model in the range of T<T_IM. The characteristics of the transport behavior for Al ion doping can be explained by terminating the double exchange channel of Mn³⁺-O^2--Mn⁴⁺ and distortion of the cell lattice. Al³⁺ substituting changed the local environment of electrons and furthermore influences on the transport properties of system.更多还原