Magnetic properties of synthesized cobalt–nickel ferrites (Co x Ni 1- x Fe 2 O 4 ) by hydrothermal method using malonic acid as a chelating agent

In the present study, cobalt–nickel ferrite nanoparticles (Co x Ni 1- x Fe 2 O 4 where x = 0, 0.3, 0.5, 0.7, and 1) have been synthesized by the hydrothermal method assisted by malonic acid. Structural and morphological studies were accomplished by FTIR, XRD, XPS, FESEM, EDAX, and TEM. Structural and morphological studies illustrate single-phase spinel ferrites with monodispersed nanoparticles. Further, the average crystallite size was calculated by Debye–Scherrer’s equation. It was found between the ranges 7.9–15.4 nm for cobalt–nickel ferrites with varying cobalt mole fractions. Cobalt–nickel ferrite particles show a non-uniform particle shape which may be a result of its magnetic behavior (particle–particle attraction). Thermal gravimetric analysis was carried out to study the heat treatment process and to obtain the oxide phase. Also, magnetic properties were analyzed by taking the help of VSM. The saturation magnetization of nanoparticles remains within the range of 33.53–77.54 emu/g and coercivity lies between 50.50 and 933.69 Oe, respectively. In our study, a simple hydrothermal synthetic method assisted by malonic acid has been performed. It is quite environmentally friendly, economical and at the same time produces particles with small-size distribution. The synthesized cobalt–nickel ferrite samples are a promising candidate for high-density recording media. Graphical abstract