Frequency and Temperature Dependent Dielectric Response of Fe3O4 Nano-crytallites

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 (??), dielectric tangent loss (tan ?) and dielectric loss factor (??) 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. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i3.17938 J. Sci. Res. 6 (3), 399-406 (2014)

Dielectric Spectroscopy of Nanostructured Polypyrrole-NiO Composites

Conducting polypyrrole-nickel oxide (polypyrrole-NiO) composites were synthesized by in situ deposition technique by placing different weight percentages of NiO powder (10, 20, 30, 40, and 50%) during the polymerisation of pyrrole. The polypyrrole-NiO composites were later characterised with Fourier transform infrared spectroscopy (FTIR) which confirms the presence of polypyrrole in the composite. AC conductivity was studied in the frequency range from 102 to 107 Hz. From these studies it is found that AC conductivity remains constant at low frequency and increases rapidly at higher frequency, which is the characteristic behavior of disordered materials. The dielectric behavior of these composites was also investigated in the frequency range 102–107 Hz. It is observed from these studies that the dielectric constant and dielectric tangent loss decrease exponentially with frequency. The composites exhibit a low value of dielectric loss at higher frequency.