Fabrication of monodispersed α-Fe2O3@SiO2 core-shell nanospheres and investigation of their dielectric behavior

We report dielectric behavior of uniformly dispersed α-Fe₂O₃@SiO₂ core-shell nanospheres prepared by employing solvothermal technique. The α-Fe₂O₃@SiO₂ core-shell nanospheres were subjected to Fourier transform infrared spectroscopy, which substantiates the presence of metal iron and silicon functional groups. Powder X-ray diffraction analysis establishes the phase purity and composition. X-ray photoelectron spectroscopy analysis demonstrates the formation of α-Fe₂O₃@SiO₂ core-shell nanospheres which is further corroborated by scanning electron microscopy images that authenticates the thickness of the shell is sufficiently larger than the core. A relatively high dielectric permittivity (1100) and low loss factor (1.51) is obtained at 1 KHz (at 40 °C). The material follows positive temperature coefficient of resistance type behavior as evidenced in the impedance analysis.