纳米复相锌铁氧体的隧道结构与相变动力学分析

Tunneling Structure and Phase-Transformation Dynamics of Two-PhaseFerrite of ZnFe2O4/Fe2O3

采用sol-gel方法制备了ZnFe2O4/Fe2O3纳米复相铁氧体.利用X射线衍射,高分辨电镜(HREM)对样品的结构进行了分析.结果表明,复相锌铁氧体是形成隧道结构的必要条件;伏安曲线和磁电阻效应等从性能上说明复相锌铁氧体具有隧道磁电阻的特性;HREM直接观测到复相锌铁氧体形成隧道结构,其中绝缘层α-Fe2O3位于晶界处,从相变动力学分析中,也证实了α-Fe2O3是由ZnFe2O4晶界或表面控制的析晶,位于晶界处.

The nanostructure ferrites of two-phase ZnFe2O4/Fe2O3 were prepared by the sol-gel method. The structure was analyzed by X-ray diffraction (XRD) and high-resolution electron microscope (HREM). The results indicate that two-phase ferrite is the necessary condition to form tunneling structure. Non-Ohmic character of I - V curve and magnetoresistance effect of two-phase ferrite also show tunneling character. The tunneling structure was directly observed by HREM in two-phase ferrite that insulating layer of alpha-Fe2O3 located in interface between ferrets. Approved deeply by phase-transformation dynamics, crystallization of alpha-Fe2O3 is controlled by the interface or surface of ZnFe2O4 crystallite.