Enhanced dielectric and magnetic performance of indium-substituted Ni-Zn ferrites for high frequency applications

The structural, morphological, dielectric, and magnetic properties of the composition Ni 0.5 Zn 0.5 In x Fe 2-x O 4 (x = 0.01,0.03,0.05,0.07,0.09) were investigated to understand the influence of indium substitution on the behavior of Ni–Zn ferrites for high-frequency applications. They were effectively synthesised utilising the sol-gel method, and the development of a cubic spinel structure with lattice parameters ranging from 7.865 Å to 7.923 Å was verified by X-ray diffraction results. As the indium concentration increased, the crystallite size decreased from 25.00 nm to 15.78 nm, and the microstrain increased from 0.98 × 10 −3 to 1.53 × 10 −3 . Raman analysis confirmed phonon softening by revealing distinctive spinel modes at lower wavenumbers, while FTIR spectra indicated two absorption bands at 524–547 cm −1 and 440-470 cm −1 , which correspond to tetrahedral and octahedral sites. The Maxwell-Wagner interfacial polarization has been identified to influence significant frequency and temperature dependency in dielectric investigations. At high temperature, the dielectric constant was a maximum of around 720 at x = 0.07 in the kHz region, while less than 100 in the MHz range. The results of the impedance study showed that when the temperature increased, the real impedance decreased from 0.58 MΩ to 0.09 MΩ (x = 0.01) and from 1.52 MΩ to 0.12 MΩ (x = 0.03), respectively, demonstrating the presence of thermally activated conduction and non-Debye relaxation. The AC conductivity increases at 0.0142 Ω −1 m −1 at x = 0.07, suggesting semiconducting properties. Magnetic measurements have confirmed soft magnetic behaviour with narrow hysteresis loops. The specific saturation magnetization decreased from 68.98 emu/g (x = 0.01) to 19.79 emu/g (x = 0.09), and the coercivity ranged from 84.43 Oe to 59.84 Oe. Composition x = 0.07 exhibited the most balanced dielectric and magnetic characteristics among the investigated samples, indicating its potential for high-frequency applications.