Frequency and temperature effects on dielectric properties of cobalt ferrite

摘要

Abstract In this work the cobalt ferrite (CoFe_2O_4) nanocrystalline powder has been synthesized by co-precipitation method. Structural characterization carried out through X-ray diffraction (XRD) spectral analysis indicates the cobalt ferrite crystallizes in the inverse cubic spinel phase with a lattice constant 8.59 A. The vibrational modes of the octahedral and tetrahedral metal complex in the sample have been examined using Fourier Transform Infra-Red (FT-IR) in the wave number range of 500 to 850 cm-1, and it shows an absorption band within this range, which confirms the spinel structure of the sample. The existence of Co, Fe and O has been evident through energy dispersive spectrum and the surface features analysis made with the help of Field Emission-Scanning Emission Microscopy (FE-SEM). The frequency (100Hz-lMHz) and temperature (T = 303-500 K) dependence of dielectric constant showed a sharp decrease with increase in frequency indicate that cobalt ferrite exhibit two dielectric relaxations at lower frequencies (100 Hz). The dielectric constant of cobalt ferrite is temperature independent up to 200 K.