Effect of Pr doping on structural, electrical and dielectric properties of ceria based system as electrolyte for electrochemical device

Abstract

Electro-ceramics are the wide choice for solid-state electrochemical devices such as batteries, solid oxide fuel cells, sensors, electrochromic windows, supercapacitors, etc as a component such as electrolytes and electrodes. Solid electrolytes play an important role to decide the operating temperature and efficiency of the devices. In the present report, we focus our efforts to explore the Pr doped (CeO2) ceria system, which is broadly used as solid electrolytes for intermediate temperature solid oxide fuel cell (IT-SOFCs). The oxygen vacancies generated by Pr doping are trapped in the defect cluster; the association energy of trapping decides the operating temperature of fuel cells. To understand the rich physics of ionic conduction in solid electrolytes in general and oxy-ion conduction in the doped ceria system in particular, the charge relaxation mechanism is needed to be studied. With this intention, pr doped ceria system Ce1-xPrxO2-δ (where x = 0.05 to 0.30) were synthesized by Hydrothermal route at ultrafine scale. Fluorite structure is confirmed by X-ray diffraction (XRD) and data is well fitted using Rietveld refinement by Full-Prof suite. The electrical properties of all gas-tight dense pellets of the Pr doped ceria system were investigated by Impedance spectroscopy at an intermediate operating temperature range. Relaxations of conducting ions are confirmed by M” as a function of frequency at various temperatures and thus M” peak height is used to quantify the density of disorder states. This study gives a novel approach to explore the relationship between dopant - structural changes- charge relaxation phenomenon - Ionic conductivity of Pr doped ceria system.