Brief review on magnetic properties of nanoferrites

Nano ferrites with molecular formula AFe2O4 (A = Mg, Mn, Co, Ni, Cu, Zn and Ba) are considered as better magnetic materials than pure metals. Iron NPs present in the nano ferrite possess high magnetic moment which gives better magnetic signals and improves the sensitivity. The high resistance, saturation of magnetization, permeability, coercivity, low cost and less power loss property of nano ferrites made them find applications in different fields. The magnetic property arises due to the interaction between metal ions occupying a particular position and oxygen ions. The occupancy of metal ions depends on the method of synthesis. The coercivity, saturation magnetization and retentivity of certain ferrites such as Magnesium ferrite, Manganese ferrite, Nickel ferrite, copper ferrite and barium ferrite were found to be maximum for autoclave, chemical bath deposition, sol gel, sol gel auto combustion methods whereas found to be minimum for coprecipitation, thermal heat treatment, auto combustion and mechanical alloying method. The change in the method of synthesis, synthesis atmosphere, calcination/annealing temperature leads to the development of oxygen content which is going to affect directly/indirectly the magnetic properties. In this brief review, we have studied the dependency of magnetic ferrites such as saturation of magnetization, retentivity and coercivity on the crystallite size and calcination temperature synthesized via different methods. We have discussed more than 70 experiments reported by different researchers.