Structural, Electrical, and impedance spectroscopy studies of Barium substituted nano calcium ferrites synthesized by solution combustion method.

Barium substituted nanocrystalline ferrites with chemical composition BaxCa1-xFe2O4 (x =0.0 to 0.25) BCAF were prepared by solution combustion method. The phase formation of mixed spinal structured ferrites was confirmed by PXRD analysis. The average crystallite size was calculated using Debye-Scherrer formula and it was found to be in the range of 27-44 nm. Surface morphology was analyzed by SEM, it reveals the highly porous nature of the synthesized samples. Nanocrystalline nature of samples was confirmed by TEM. The real and imaginary part of dielectric constant (ε′ & ε′′), dielectric loss factor (tan δ) and AC conductivity (σac) of the samples were measured using LCR meter in the frequency range of 100 Hz–5 MHz at room temperature. The dielectric constant of the synthesized ferrite samples was found to decrease with increase in frequency and finally reaches a constant value at higher frequencies which is typical behavior of dielectric ferrites. The observed dielectric dispersion is of Maxwell-Wagner type interfacial polarization. The contribution of grain boundary resistance has been studied from the cole-cole plots. The impedance spectroscopy analysis confirms the non-Debye type of conductivity relaxation for the nanocomposite. The high value of the dielectric constant makes the material suitable for miniature memory devices based capacitive components or energy storage devices. The samples also show low dielectric losses at high-frequency region which make them suitable for high-frequency applications and also long relaxation time of BCAF nanocomposites could make them suitable for nano scale spintronic devices.