RT and temperature-dependent dielectric behaviour of NiAl2O4-Effect of calcination temperature

Abstract

Sol gel auto-combustion was used to create nickel aluminate nanoparticles having the chemical composition NiAl₂O₄, which were then calcined at 700, 900, 1100, and 1300 °C for the present study. In order to evaluate the phase purity and validate the spinel structure and Fd3m space group of the prepared sample, the X-ray diffractometry result was examined at room temperature using the Rietveld refinement method. The LCR meter has been used to study dielectric properties such as the dielectric constant, tangent loss, and A.C. conductivity. The dielectric parameter, impedance, and A.C. conductivity changes were investigated as a function of temperature and frequency wherein temperature in the range 200–800 °C, and frequency in the range 1 Hz–10 MHz. The value of the dielectric constant was observed in the range 1.5⨯10³–7.25⨯10⁸ at room temperature and 2.8⨯10⁷–1.6⨯10⁹ at temperature span of 200 °C–800 °C. It has been found that the dielectric loss of produced aluminates decreased with the calcination temperature, hence, the sample calcined at 1300 °C would be a good choice for low loss applications. The semicircle character of the Cole-cole plots was exhibited by all the samples at room temperature and in the temperature range 200–800 °C. It has been found that the dielectric properties decrease with increasing frequency and temperature between 200 and 800 °C and Maxwell-Wagner interfacial polarization strongly supported these results.