Synthesis and magnetic properties of MCr2O4(M = Co, Zn) nanocrystalline

MCr2O4(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 CoCr2O4 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 × 10s A/m, 1.93 × 104 A/m, 19.86 A&middotm2/kg and 12.63 A&middotm2/kg, respectively, which are explained by the magnetic spin disorder of surface atoms resulted from surface structure defects of CoCr2O4 nanocrystalline.