Impedance spectroscopy studies of ErNbO4 synthesised by the sol–gel method

Abstract

In this work, we report the dielectric study of erbium niobate ceramic synthesised by the sol–gel method. X-ray diffraction patterns confirmed the presence of monoclinic ErNbO4, even at the lowest heat-treatment temperature. The frequency dependence dielectric study shows that the value of the dielectric constant, particularly at lower frequencies, is highly influenced by the secondary phase. Impedance spectroscopy analyses revealed a non-Debye relaxation phenomenon in the sample heat-treated at 800 °C. The Nyquist plot from the complex impedance spectrum showed only one semicircular arc, representing the grain effect in the electrical conduction. The modulus mechanism also indicates the non-Debye type of relaxation in the material, which is supported by impedance data, and confirms that the relaxation process is due to short-range motion of charge carriers. Relaxation times, extracted using the imaginary parts of complex impedance and modulus, were found to follow the Arrhenius law. The thermal evolution of the conductivity of the grains also presents an Arrhenius-type behaviour, revealing that charge carriers have to overcome different energy barriers while conducting and relaxing.