Investigations on Positive (Sm³⁺) and Negative (Ho³⁺) Association Energy Ion Co-doped Cerium Oxide Solid Electrolytes for IT-SOFC Applications

Novel compositions of positive (Sm³⁺) and negative (Ho³⁺) association energy ion co-doped cerium oxide solid electrolytes were synthesized and analyzed for intermediate-temperature solid oxide fuel cell (IT-SOFC) applications. Powder x-ray diffraction (XRD) and Raman studies confirmed the phase of pure cubic fluorite structure, while densely packed porous-structured morphology was affirmed with high-resolution scanning electron microscope (HR-SEM) micrographs. The formations of oxygen vacancies and association energies were analyzed through optical properties using ultraviolet (UV) and photoluminescence (PL) spectra. Thermal analysis revealed high thermal stability without any structural deformations and a high thermal expansion coefficient at the intermediate temperature range. The incorporation of Sm³⁺ ions acts as an oxygen vacancy generator which influences the ionic conductivity properties, and Ce_0.8Sm_0.1Ho_0.1O_2−δ solid electrolyte showed the high conductivity of 0.72 × 10⁻² S/cm at 600°C specifying that this solid electrolyte might be an excellent candidate for IT-SOFC applications.