| Abstrakt: |
Novel compositions of Nd3+and Dy3+codoped cerium oxide according to the system of Ce0.8Ndx–yDyyO2–{x–y/2+y}(x= 0.2; y= 0.04, 0.08, 0.1) have been synthesized by a simple sol–gel method and studied as electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Thermal, microstructural, optical, and electrical properties have been enhanced to different extents by the addition of Nd3+and Dy3+ions in cerium lattice, in particularly Dy3+ions because of their low ionic radius mismatch. Thermogravimetric/differential scanning calorimetric (TG/DSC) analysis exhibited a small weight loss and high thermal stability in the intermediate temperature range (400–800 °C). The addition of Dy3+ions stabilized the cubic fluorite structure, which is confirmed from X-ray diffraction (XRD) studies. Lattice parameter expansion and contraction have been observed on account of their ionic radii trend. The formation of cubic fluorite structure has been confirmed by high-resolution transmission electron microscopy (HRTEM) along with XRD studies. Addition of Dy3+ions acts as an oxygen vacancy generator that increases the oxygen vacancy concentration and efficient conversion of Ce4+to Ce3+, which are affirmed with optical studies. Complex impedance analysis was performed at the temperature range from 300 to 600 °C in air atmosphere. Compositions of the system Ce0.8Ndx–yDyyO2–{x–y/2+y}(x= 0.2; y= 0.04, 0.08, 0.1) offer competitive oxide ion conductivities in the intermediate temperature range. Ce0.8Nd0.1Dy0.1O1.85has been found to be an optimum composition with superior oxide ion conductivity of 2.2 × 10–2S/cm at 600 °C and activation energy of 0.83 eV. Oxide ion conductivity is largely enhanced by the introduction of Dy3+at intermediate temperature due to the low ionic radius mismatch, concentration of surface oxygen vacancies, and stabilization of cubic fluorite structure. Hence, these results suggest that the composition of Ce0.8Nd0.1Dy0.1O1.85can be a potential electrolyte for IT-SOFC applications. |
