Conduction mechanisms, relaxation dynamics, and magnetic properties of Se-substituted Sr nanohexaferrites

In this study, Se-substituted Sr nanohexaferrites (SrSe3xFe12− 4xO19 (Se→Sr) (x ≤ 0.10) NHFs) have been synthesized via sol-gel combustion route. The X-ray diffraction technique was utilized in order to assess the phase formation of the samples. Furthermore, morphology and crystallinity were shown by SEM, TEM, and HR-TEM investigations. M − H curves are consistent with the response of ferrimagnetic materials under an externally applied magnetic field. A “wasp-waist” behavior was also seen in the registered M − H hysteresis loops. The magnetic investigations displayed an increased tendency for Ms, Mr and Hc as the concentration of selenium (Se) ions increased, achieved their maximum values for the sample with x = 0.05, then reduced as the concentration of Se ions further increased (x > 0.05). The maximum values achieved for the product with x = 0.05 might be useful in permanent magnet applications. This study also investigates the electrical and dielectric properties of Se-substituted Sr-NHFs through AC and DC conductivity measurements, activation energy analysis, and impedance spectroscopy. Results show that Se substitution modifies charge transport by enhancing hopping and thermally activated conduction mechanisms. AC conductivity displays power-law frequency dependence, while DC conductivity reveals temperature-activated behavior. Dielectric measurements indicate reduced dielectric constant and loss at higher frequencies due to interfacial polarization. Cole–Cole and Nyquist analyses confirm non-Debye relaxation and highlight changes in grain and grain boundary effects with Se content. These findings demonstrate the material’s potential for high-frequency devices, energy storage, and electromagnetic shielding applications.