Structural Modification of Sol-Gel derived Nickel Ferrite and its derivatives via Rare Earth Doping and Its Impact on Electrical Properties

Abstract

Nickel ferrite (NiFe₂O₄), known for its exceptional magnetic behaviour and high electrical resistance, is commonly used in magnetic sensors, transformers, and high-frequency electronics. However, its inherent electrical qualities frequently require improvement for application in more demanding technological situations. This paper examines the structural and electrical evolution of nickel ferrite generated in sol-gel using rare earth (RE) ions such Gd³⁺, La³⁺, Nd³⁺, Sm³⁺, and Ho³⁺. Because of their greater ionic sizes and different electronic structures, these dopants cause significant lattice distortions, change cation site distributions, and, at higher concentrations, generate secondary non-spinel phases. These alterations greatly impact electron transport by affecting the Fe²⁺/Fe³⁺ hopping process. This allows for manipulation of resistivity and dielectric characteristics. The article also examines how critical synthesis parameters, such as solution pH and combustion agent selection, affect phase formation and microstructural uniformity. RE replacement improves the dielectric constant, loss characteristics, and electrical conductivity of these modified ferrites, highlighting their potential in applications such as electromagnetic interference (EMI) shielding, energy storage systems, and downsized electronic components. The research continues by discussing optimization tactics for dopant inclusion and synthesis conditions in order to modify functional features of Nickel ferrite family for future device integration.