复合多铁材料NiFe2O4/BaTiO3的制备及性能

采用溶胶-凝胶与固相反应相结合的方法制备了xNiFe2O4/(1-x)BaTiO3(x=0.1,0.2,0.3,0.4,0.5,0.6)系列复合多铁材料.X射线衍射(XRD)结果表明,复合材料中只含有钙钛矿结构的BaTiO3和尖晶石结构的NiFe2O4,说明共烧过程中两者未发生明显的化学反应,铁电相与铁磁相共存.扫描电子显微镜(SEM)观测结果表明材料内部是异质结构的,高分辨透射电子显微镜(HRTEM)观测结果进一步说明了NiFe2 O4和BaTiO3共存,并且在两种物质的接触处能够看到清晰的界面.这种由BaTiO3和NiFe2 O4组成的复合材料对外同时表现出铁电性和铁磁性.电滞回线结果表明,该复合材料具有铁电性,但存在着一定的漏电.介电频谱表明材料的介电常数随着频率的升高而下降,在低频下达到定值,并且铁磁相的含量对材料的介电性有影响.磁性能测试结果表明材料的磁性源于NiFe2O4,并且磁性随着NiFe2O4含量的增加而增强.

Synthesis and Properties of NiFe2O4/BaTiO3 Multiferroic Composites

Through sol-gel and solid state sintering method, xNiFe2O4/(1-x)BaTiO3(x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6) multiferroic composites were synthesized. X-Ray diffraction(XRD) result indicates the coe-xistence of both spinel NiFe2O4 and pervoskite BaTiO3 phase. Scanning electron microscopy(SEM) images show that the composites are heterogeneous structure. From the high resolution transmission electron microscopy(HRTEM) image, the interface of the two phases is obviously observed. xNiFe2O4/(1-x)BaTiO3 compo-sites exhibit both ferroelectric and ferromagnetic properties and the polarization-electric field(P-E) loops indicate the ferroelectric property of the composites with the tendency of leakage. The effects of frequency on dielectric constant (εr) of composites show εr of the composites decrease with increasing the frequency and reach a constant value in the low frequency. The content of the ferromagnetic phase also has influence on the dielectric property. The magnetic measurement of the composites indicates the mangetic properties of the composites originate from NiFe2O4 and the magnetization of composites increases with increasing the content of NiFe2O4.