CoFe2O4 bulk, nanoparticles and layer: A comparison of structural, magnetic, and optical properties

The structural characteristics of materials change with the reduction of dimensions, and they show different behaviors compared to the corresponding bulk sample. To study these changes, in this research, we investigated the effect of size and preparation method on properties of cobalt ferrite (CoFe2O4). After synthesis of a bulk sample by solid-state reaction method, CoFe2O4 nanoparticles were prepared by two different methods of co-precipitation and thermal decomposition. Then, a layer of CoFe2O4 was prepared by a spin coating method, using a silicon substrate. In the following, the structural, magnetic, and optical properties of samples were studied, and compared. The results confirmed the size and synthesis method dependence behavior of properties of the prepared samples. The nanoparticles synthesized by thermal decomposition method show much higher coercivity compared to those prepared by co-precipitation, while both consist of almost same size distribution. The bulk sample shows the lowest coercivity, but highest saturation magnetization among the samples. On the other hand, the bulk sample has smaller band gap compared to the nanoparticles.