Investigation of electrical conduction in Ca6-xNa2Y2(SiO4)6F2:xEu3+ ceramic by complex impedance and electric modulus spectroscopy

Abstract The electrical conduction mechanism of Ca6-xNa2Y2(SiO4)6F2:xEu3+ fluorapatite ceramic with (x = 0–0.05 mol%) synthesized by solution combustion method has been investigated by dielectric, complex impedance and electric modulus spectroscopy. Microstructural analysis was carried out by scanning electron microscopy (SEM) which shows that the spheroidal and ellipsoidal grains were distributed uniformly in the prepared ceramic with average grain size of the order of 3 μm. The electrical and dielectric studies of the ceramic were done in the frequency range of 100 Hz–100 KHz and temperature range of 50 °C–500 °C. The temperature and frequency dependent dielectric loss and dielectric constant decreases with an increase in frequency due to the ceasing effect of polarization. Dielectric relaxation behaviour of the prepared ceramics were studied using Complex impedance spectroscopy (CIS). Nyquist plots show that with increase in Eu3+ ion concentration the resistance of grains and grain boundaries decreases for the prepared ceramics. The investigation of charge transport phenomena was done by electric modulus spectroscopy. The drastic increase in a. c conductivity with increase in temperature shows that the ceramic follow the Jonscher’s power law and appear Debye in nature.