Frequency and Temperature Dependent Dielectric Response of Fe₃O₄ Nano-crytallites

Abstract

Magnetite nanoparticles have been prepared by using sol-gel auto combustion technique. The samples are prepared by using different concentrations of fuel. Structural characterization has been done using X-Ray diffraction technique and it was observed that fuel concentration can affect the structural properties of Magnetite nanoparticles. The dielectric properties for all the samples such as dielectric constant (ɛ ′), dielectric tangent loss (tan δ) and dielectric loss factor (ɛ ″) have been studied as a function of frequency and temperature in the range 10 Hz-20 MHz and it was found that these nanoparticles can be used in microwave devices because of their good dielectric behavior.

Graded-permittivity polymer nanocomposites as superior dielectrics

“…The Rietveld quantitative phase analysis (Figure 2) performed on Fe3O4@TiO2 NP before and after calcination evidenced how this step induced a partial crystallization of the TiO2 phase, which went from being completely amorphous to exhibiting ≈35 wt% of anatase (Table 1). Based on the results of this analysis, the dielectric constant r of the Fe3O4@TiO2 NP before and after the calcination step was estimated to be equal to 21 and 31, respectively, 7 using a rule-of-mixture [13] (with εanatase=50 [13], εamorphous=15 and εmagnetite=10 [14] where εamorphous was calculated by averaging the values of the dielectric constant for amorphous TiO2, assumed to be equal to 20 [15] and for amorphous Fe3O4, assumed to be equal to 10 [14]). In light of the results of the magnetic and diffractometric analyses, the execution of a calcination step at 450°C for 6 hours was considered a good compromise between the reduction in magnetization and the increment in permittivity.…”