Changes in Fe2+/Fe3+ molar ratio for the formation of spinel CoFe2O4 layered double hydroxide nanoparticles

A facile, fast, and cheap method has been proved for large-scale synthesis of super-paramagnetic CoFe2O4 nanoparticles (CNPs) by the co-precipitation process without surfactant and followed by calcination. In order to fabricate layered double hydroxide nanoparticles, the molar ratio Fe2+/Fe3+ should be changed and confirmed by transmission electron microscopy. Also, all synthesised CNP samples were characterised by X-ray diffraction and vibrating sample magnetometer to investigate the relationship between the crystal size and the saturation magnetisation. The good correlation between the influence of Fe2+/Fe3+ ratio change and the initial pH showed that the slower formation of CNPs was obtained at higher concentration of NaOH and Fe3+. Also, the critical role for the crystal size, morphology, magnetisation characters, and cation distribution in the spinel structure was described well. Furthermore, the maximum saturation magnetisation and crystal size were obtained at the percentage Fe2+/Fe3+ (1:1). The results stated that the synthesised CNPs had the potential to become a promising material in large scale.