The impact of Bi3+ ions on magnetization, dielectric parameters, and conductivity of soft Mg-Cu ferrite nanoparticles

Abstract

This paper investigates the bismuth ions leverage on magnetic and dielectric features of magnesium–copper nanoferrites Mg0.5Cu0.5BixFe2-xO4 (MCBF). The Mg0.5Cu0.5Bi0.1Fe1.9O4 nanoferrite exhibits superior magnetic properties compared to the pure Mg-Cu sample. These properties include a higher magnetization of 31.31 emu/g, with an enhancing ratio of 1.50 %. Additionally, it demonstrates a higher initial permeability of 17.84, with an enhancing ratio of 55.12 %. Furthermore, their coercivity is lower at 59.90 Oe, with an enhancing ratio of 50 %. All MCBF nanoferrites exhibit a high-frequency response between 6.106 and 6.926 GHz, making them suitable for microwave technology. The dielectric parameters dispersion shows normal behavior at different frequencies and temperatures. As for dielectric parameters dependence on Bi content, it exhibited a peculiar manner. At a temperature of 297 K and a frequency of 50 Hz, the nanoferrite Mg0.5Cu0.5Bi0.1Fe1.9O4 exhibits superior dielectric properties compared to the pure Mg-Cu sample. Specifically, it demonstrates the highest dielectric constant of 360.68, with an enhancing ratio of 125.97 %. Additionally, it displays the highest conductivity of 691.4 µ(Ω.m)-1, with an enhancing ratio of 1543.23 %. Furthermore, the nanoferrite exhibits a lower dielectric loss of 6.49, with an enhancing ratio of 80.22 % compared to the pure Mg-Cu sample. The conduction mechanism of the Mg0.5Cu0.5BixFe2-xO4 nanoferrites was determined by fitting the σac results via the Jonscher power law. This conduction mechanism is attributed to correlated barrier hopping (CBH) model up to 473 K, followed by small polaron tunneling (SPT), which reaches higher temperatures. Hence, the Mg0.5Cu0.5Bi0.1Fe1.9O4 nanoferrite has a remarkable magnetic and dielectric nature, which can be used as functional soft ferrite material in transformers and high-frequency electronic devices.