A study on the electrical and dielectric traits of ternary NiCuZn-spinel ferrites co-substituted with Ga3+-Gd3+ ions

Abstract

This report focus on the effect of Ga-Gd co-substitution on the structural, conductivity and dielectric properties Ni0.4Cu0.4Zn0.2GaxGdxFe2-2xO4 (x ≤ 0.04) nanospinel ferrites (NCZGaGd NSFs). Some consequential electrical and dielectric parameters of NCZGaGd NSFs have been extensively assessed as functions of bias frequency, measurement temperature, and co-substitution ratios in logarithmic 3D graphs by complex impedance spectroscopy. XRD analyses verified the cubic spinel structures. The morphology and chemical composition of all products have been investigated by TEM and FE-SEM along with EDX. The different substitution ratios of both Ga and Gd ion were used to synthesize NCZGaGd NSFs via sonochemical approach using ultrasonic irradiation. These parameters such as ac/dc conductivity, dielectric constant and loss, dissipation factor and Cole-Cole plot analysis have been extensively evaluated for frequencies up to 3.0 MHz at temperature between 20 °C and 120 °C. It is verified that the ac conductivity obeys the power law frequency rule for each co-substitution ratio, and it is also understood from the reactive changes in the graphs that the dependence of both temperature and co-substitution ratios in ternary NiCuZn NSFs is highly effective in terms of grains and grain boundaries as well as the number of elements in its composition. It was observed how the activation levels and dc conductivity trends from the Arrhenius plot changed with the co-substitution of Ga3+-Gd3+ ions to ternary NiCuZn NSFs; this implies that the conduction mechanism is due to both polaron and electron hopping as well as ionic contribution. All dielectric parameters were noted to undergo moderate frequency-dependent variation at temperatures up to 120 °C for the various Ga3+-Gd3+ ions co-substitution ratios. Nyquist plots of the Cole-Cole impedance functions show a semicircle of various diameters depending on temperature and co-substitution ratio; This indicates that the resistive and capacitive responses of ternary NiCuZn NSFs are due to the contribution of grains and grain boundaries, and ions in the compositional element formed in the structures of the ternary NiCuZn NSFs. Extensive changes in fitting parameters of Nyquist plots of Cole-Cole impedance functions show that there is much contribution on the conduction mechanism due to the complexity of the co-substituted ternary NiCuZn NSFs system.