Study On The Property Of Ceria-Based Solid Electrolyte

This dissertion aimed at studying on the effects of doping kinds of oxides in ceria-based electrolyte. The electrical property was evaluated on the theoretical analysis and experimental results.In the scale of atoms, the defect behaviors, such as fundamental point defect, defect complex formation and oxygen vacancy migration in ceria doped with alkaline earth oxides MO (M2+: Ca2+, Sr2+, Ba2+, Mg2+) and trivalent metal oxides M2O3 (M3+: Al3+, Y3+, Gd3+, La3+), were studied on the basis of energy minimization calculations by means of GULP procedure.By modeling defect behavior of ceria doped with MO, it shows that the solution energy of Ca2+ is lower than that of Sr2+, Ba2+, Mg2+ via an oxygen vacancy charge compensation mechanism; lattice constants of ceria doped with CaO, SrO, BaO increase with doping concentration, while they decrease with doping MgO concentration; the binding energy to form[MCe · Vo]~× defect pair is lower for Ca2+ than other alkaline- earth cations; the charged defect complexes [Vo· Mce· Vo] are not stable in ceria lattice, however, neutral defect complexes[Vo · MCe· Vo ·MCe]× are stable in the doped ceria; the preferred route for oxygen vacancy withthe lowest migration energy is from the second neighbore site to another one.By modeling defect behavior of ceria doped with M2O3, it shows showed that the solution energy of Gd3+ is lower than other trivalent metal ions, but for Al3+, it is higher than lanthanon ions in the solution reaction; lattice constants of ceria doped with Gd2O3 or La2O3 increase with doping concentration, while they decrease with doping concentration of Y2O3; oxygen vacancy tends to be in the first neighbor site of doping cations which have a smaller ionic radius than Gd3+, but it tends to be in the second neighbor site of doping ions which have a bigger radius than Gd3+; the association energy to form defect pair is higher for dopant Gd3+ than other trivalent cations, while it is the lowest for Al3+; the oxygen vacancy migration energy of dopant cation Al3+ is the highest among these trivalent cations. Therefore, doping lanthanon oxides have a good effect on improving the conductivity of ceria-based electrolyte.Ceria-based electrolyte doping kinds of oxides was prepared by solid reaction process. The error percent is 4% between measured and computed value of conduction activation energy of dopant Gd3+. The difference between measured and computed value of conduction activation energy of doping Ca2+ is large.