MCr_2O_4(M=Co,Zn)纳米晶的合成及磁性

Synthesis and magnetic properties of MCr_2O_4 (M=Co,Zn) nanocrystalline

通过配合物热分解法制备MCr2O4(M=Co,Zn)纳米晶,并对其物相、表面微结构和磁性进行表征。结果表明,产物为直径40 nm左右的球形粒子,具有立方晶系尖晶石结构。磁滞回线表明,CoCr2O4在低温下表现出明显的亚铁磁性和较强的交换偏置场,矫顽力和交换偏置场分别为Hc=6.05×105A/m和He=1.93×104A/m,饱和磁化强度Ms和剩余磁化强度Mr分别为19.86和12.63 A.m2/kg,这可用CoCr2O4纳米晶的表面结构缺陷导致表面原子的磁结构自旋无序来解释。

MCraO4 （M=Co, Zn） nanocrystalline were synthesized by the thermolysis of complexes. Their phase, surface microstructure and magnetic properties were characterized. The results indicate that the products have a spinel structure with cubic system, and are spheric particles with crystallite size of about 40 nm. The hysteresis loops show that CoCr2 O4 has a clear ferrmagnetism and an exchange bias filed at lower temperature. It is observed that the coercivity, exchange bias filed, saturation and remanence magnetization are 6.05 ×10^5 A/m, 1. 93 × 10^4 A/m, 19.86 A · m^2/kg and 12.6a A · m^2/kg, respectively, which are explained by the magnetic spin disorder of surface atoms resulted from surface structure defects of CoCr2O4 nanocrystalline.