Dielectric behavior and complex impedance analysis of Ti-doped Mg_0.5Cu_0.5Mn_0.4Fe_1.6O₄ ferrites

Abstract

Pure sample Mg_0.5Cu_0.5Fe₂O₄ (MCF) and composition in chemical formula Mg_0.5Cu_0.5Mn_0.4Ti_xFe_1.6-xO₄ (0.0 ≤ x ≤ 0.6) were prepared by the solid-state reaction method. Structural analysis showed a single-phase spinel structure till x = 0.3. The average grain size was found in the range 71–141 nm. The lattice parameter of spinel structure depends on the complex interplay between ions size, and their distribution in tetrahedral (A) and octahedral [B] sites. Electrical properties were studied in the frequency range of 20 Hz–5 MHz at different temperatures. The process of dielectric polarization in ferrites takes place through the effect of hopping between Fe³⁺ ↔ Mn³⁺. Temperature and frequency dependence of AC conductivity were explained based on the Verwey mechanism. The low values of dielectric loss for doped samples with (x = 0.15 and 0.30) confirming their applicability in high-frequency memory devices. Impedance study using Cole–Cole representation revealed the appearance of a single semicircle. The bulk conductivity (σ_dc) evaluated from the complex impedance spectrum shows a smallest value of the activation energy for sample x = 0.6, while the sample x = 0.3 represents the largest value. Impedance parameters values such as resistance (R_g), capacitance (C_g), and activation energy (τ_g) for the samples at different temperatures were deduced. The grain resistance depends on the titanium concentration, while the activation energy decreases with increased temperatures.