Fabrication and unravelling the impact of iron-deficiency amount on crystal structure, micromorphology, elastic and electromagnetic properties of Ni0.25Cu0.13Zn0.62Fe2−xO4−3x/2 ferrites under different sintering temperatures

In this work, polycrystalline Ni0.25Cu0.13Zn0.62Fe2−xO4−3x/2 ferrites were synthesized via the solid-state reaction route and sintered at four different temperatures (1100–1250 °C; in steps of 50 °C) to investigate the impacts of iron-deficiency amount on the structural, micromorphology, elastic, and electromagnetic properties. The crystal structure, phase formation, micromorphology, and grain size were examined through X-ray diffraction, Fourier transforms infrared spectroscopy and scanning electron microscopy. The structural analysis confirms the evolution of the cubic spinel skeleton without any impurity phase. The lattice parameter increases linearly with iron-deficiency amount at 1100 °C, while it varies non-linearly at 1150, 1200, and 1250 °C. The elastic properties such as stiffness constants, elastic constants, longitudinal wave velocity, transverse wave velocity, mean elastic wave velocity, Poisson’s ratio, and Debye temperature were calculated from infrared spectroscopic data. The elastic moduli were corrected via Hassselman and Fulrath, Ledbetter and Datta, and the elastic theory models. The microstructural analysis reveals that agglomerated and abnormal grain growth and agglomerations take place due to the magnetic interaction between the individual grains. An improvement in dielectric properties with sintering temperature is evident due to the improved densification and generation of Fe2+ ions. The AC conductivity analysis suggests that the electrical conduction process is attributed to the small polaron hopping. Nyquist representation proclaims that the electrical conduction is ascribed to the contribution of the grain boundary. The observed variations in permeability and magnetic loss with iron-deficiency amount may be accredited to the modification of density, porosity, grain size, and anisotropy contribution.