Comprehensive analysis of Ni_0.4Cu_0.2Zn_0.4Fe_2-4xSn_3xO₄ nanospinel ferrites: Structural, electrical, and dielectric characterization through advanced techniques

This study extensively investigates Ni_0.4Cu_0.2Zn_0.4Fe_2-4xSn_3xO₄ (x ≤ 0.10) nanospinel ferrites, denoted as NCZFe_2-4xSn_3xO₄ NSFs, focusing on their structural, morphological, electrical, and dielectric characteristics. Utilizing various techniques such as SEM, EDX, TEM, XRD, and impedance analysis, the research confirms the cubic spinel structure and composition of the nanoferrites. The substitution of Sn⁴⁺ ions into Ni_0.4Cu_0.2Zn_0.4Fe₂O₄ NSFs is explored, with a thorough examination of dielectric and electrical parameters up to 1.0 MHz and temperatures ranging from 20 to 180 °C. Complex impedance spectroscopy is employed to represent these parameters in a logarithmic 3D graph, revealing insights into ac/dc conductivity, activation energies, dissipation factor, dielectric constant, and loss. The study observes adherence to the power-law frequency rule in ac conductivity and highlights the impact of temperature and substitution ratios on grains, grain boundaries, and elemental composition. The investigation suggests a conduction mechanism involving electron and polaron hopping, and ionic contributions. Dielectric parameters show frequency-dependent changes that relate the dielectric constant to space charge polarization, inhomogeneous dielectric structure, impurities, and grains/grain boundaries. Cole-Cole impedance plots display semicircles dependent on substitution ratios and temperature, emphasizing contributions from grains, grain boundaries, and ionic mobilities. The Nyquist plots of Cole-Cole impedance functions further underscore substantial complexity in the conduction mechanism of the substituted NCZFe_2-4xSn_3xO₄ NSFs.