Effect of Er³⁺ and Y³⁺ ions co-substitution on conductivity and dielectric features of Mn-Zn nanosized spinel ferrites

In this study, we have synthesized unique Mn_0.5Zn_0.5Er_xY_xFe_1.8-2xO₄ (x ≤ 0.1) SFNPs via ultrasonication (sonochemical) approach. Electrical and dielectric features of Mn_0.5Zn_0.5Er_xY_xFe_1.8-2xO₄ SFNPs were inspected comprehensively using impedance spectroscopy up to 3.0 MHz from 20 to 120 °C for a various substitution ratio of Er³⁺ and Y³⁺ ions. The fundamental electrical and dielectric parameters which are AC/DC conductivity, activation energy, dielectric loss, dielectric constant, and tangent loss were studied in the determined frequency and temperature ranges. The experimental results showed that ac conductivity obeys the power law equation and the value of n changes considerably with the co-substitution of Er³⁺ and Y³⁺ ions in various ratios, however, exhibiting some dependencies over a given temperature range. The DC conductivity and activation energy curves show a significant variation with temperature and co-substitutional ratios of Er³⁺ and Y³⁺ ions. The conduction mechanisms can essentially be assigned to the grain–grain boundaries. Therefore, frequency-dependent dielectric properties of Mn_0.5Zn_0.5Er_xY_xFe_1.8-2xO₄ SFNPs can be described by means of the Koop's model. It is revealed that conductivity and dielectric properties of Mn_0.5Zn_0.5Er_xY_xFe_1.8-2xO₄ SFNPs are adjustable with co-substitutional ratios of Er³⁺ and Y³⁺ ions.