Microstructure and magnetic properties of nanocrystalline Co1−xZnxFe2O4 ferrites

Nanocrystalline Co1−xZnxFe2O4 ferrites with spinel phase were prepared by a spraying-coprecipitation method. Experimental results indicate that the average grain size of Co1−xZnxFe2O4 ferrites calcined at 973 K for 1.5 h is about 32 nm and more uniform. The obtained smaller and more uniform particle size can be ascribed to the effect of entrainment and turbulence for jet in the spraying-coprecipitation approach. Magnetic property shows that the saturation magnetization of the nanocrystalline Co0.7Zn0.3Fe2O4 ferrite is enhanced to 83.4 A m2 kg−1. Moreover, the remanent magnetization and coercivity of nanocrystalline Co1−xZnxFe2O4 ferrites decrease with the increase of zinc concentration. The specific saturation magnetization and remanent magnetization of Co0.5Zn0.5Fe2O4 ferrite increases with the increasing grain size. The maximum coercivity of Co0.5Zn0.5Fe2O4 ferrite reaches up to 7.6 × 103 A m−1, as the grain size is 32 nm. The value of ferromagnetic exchange length in Co0.5Zn0.5Fe2O4 ferrite is about 42 nm. The magnetic behavior of Co0.5Zn0.5Fe2O4 ferrites may be attributed to the effect of nanometer size of magnetic particles.