Dielectric polarization and charge transport in Gd-doped Fe3O4 nanocrystals for energy storage and electronic devices.

Gd-doped magnetite (Gd x Fe3-x O4) nanocrystals were synthesized via the co-precipitation method with an aim to study the effect of rare-earth substitution on their structure, shape, and dielectric and magnetic properties. Structural analysis using X-ray diffraction revealed that the samples formed a single-phase cubic spinel structure with minor lattice distortion upon Gd substitution. Nanocrystalline materials were characterized as cluster-like grains using field-emission scanning electron microscopy. Fourier transform infrared spectroscopic analysis provided evidence of a spinel structure and revealed metal-oxygen vibrations at the tetrahedral and octahedral sites. From the dielectric analysis, improved dielectric permittivity at lower frequencies, attributed to Maxwell-Wagner interfacial polarization, and lower dielectric loss at higher frequencies indicate their potential for dielectric and energy-related applications. The application of an alternating current to the materials revealed conductivity consistent with the thermally activated hopping mechanism and the correlated barrier hopping model. Magnetic analysis revealed a soft magnetic material with lower coercivity and moderate saturation magnetization. The combined structural, dielectric, electrical, and magnetic characteristics highlight the potential of Gd-doped magnetite nanocrystals for future energy-related and electronic applications.