Abstract
In this research work, highly dense BaZr0.85Ho0.10Y0.025Nd0.025O3-δ electrolyte ceramic was synthesized through a cost-effective flash pyrolysis route followed by conventional sintering for intermediate-temperature solid oxide fuel cells. The calcined powder and sintered pellet were characterized through various techniques like HRXRD, HRTEM, FESEM, EDS, and Raman spectroscopy. The XRD pattern of calcined and sintered pellet shows the pure cubic phase with space group symmetry through the Rietveld refinement. The study of the electron density distribution of calcined powder and sintered pellet calculated by the maximum entropy method reveals the presence of oxygen vacancies at the octahedral site in the sintered sample. The microstructure of the fracture surface of the sintered sample indicates highly dense with a relative density of 97.4% through FESEM. The Raman analysis confirms the distortion along the c-axis and oxygen vacancies in the octahedral site of BaZr0.85Ho0.10Y0.025Nd0.025O3-δ. Impedance spectroscopy measurements was conduct in the temperature range of 50 to 700 ℃ and frequency range of 1 Hz to 1 MHz. The Nyquist plots in the temperature range of 350 to 700 ℃ provide information of three types of relaxations corresponding to grain and grain boundary, and electrode effect. The temperature-dependent exponent (n) associated with grain and grain boundary decreases with the increase in temperature, indicating that large polaron hopping is involved in the electrical conduction mechanism.