Nano cobalt ferrites: Doping, Structural, Low-temperature, and room temperature magnetic and dielectric properties - A comprehensive review

Instruments and devices based on magnetic materials have become necessity and indispensable for human being in the modern culture. The applications of these material are growing exponentially ever since the first magnetic mineral known to humanity, loadstone magnetite, Fe3O4. Ferrites based materials take the lion share in magnetic materials. Among the spinel ferrites, cobalt ferrite (CFO) has got much attention of various research groups during the last decades due to its applications in household items to high density data storage and magnetic resonance imaging (MRI) contrast agents to camouflaging military installations and stealth applications. The CFO is hard magnetic material with high anisotropy constant and Curie temperature yet versatile due to its moderate saturation magnetization with flexible dielectric and transport properties. Many elements of periodic table with variable amount can be incorporated in cobalt ferrite spinel matrix at both tetrahedral and octahedral sites by a wide variety of dry and wet chemical synthesis routes to tailor physical properties for various applications. This systematic review focuses types of ferrites, structure, and room-temperature (RT) and Low-temperature magnetic dielectric properties of pristine and metal doped CFO. This article gives an overview of X-ray diffraction (XRD) and effect of calcination temperature, Fourier transform infrared spectroscopy (FTIR) techniques. Room tem-perature (RT) and Low-temperature Field cooled (FC) and zero field cooled (ZFC) magnetic properties, dielectric Properties, ac conductivity and impedance spectroscopy of pristine and doped CFO. Furthermore, the impact of some group II and transition metal doping on various properties of CFO and their application were reviewed. The final section deals with doping of CFO by Rare-earth (RE) (La, Ce, Sm, Gd, Dy and Er) reviewing their structural, magnetic, and dielectric properties and applications. Overall, this review article reports the structural, RT and Low temperature magnetic, dielectric properties of CFO, besides doping of CFO by transition and RE metals, highlighting the recent research on CFO Nanoparticles.