【作者】 马志芳；

【导师】 梁广川；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2005， 硕士

【摘要】 本文针对掺杂的氧化铈基中温固体氧化物电解质材料进行了研究,在理论分析和实验的基础上探讨了掺杂剂对电解质电学性能的影响。 在原子尺度,采用能量最小化算法,运用GULP程序,对掺杂碱土金属氧化物MO(M²⁺:Ca²⁺,Sr²⁺,Ba²⁺,Mg²⁺)和三价金属氧化物M₂O₃(M³⁺:Al³⁺,Y³⁺,Gd³⁺,La³⁺)的CeO₂电解质材料的缺陷行为,如基本点缺陷,缺陷复合体形成和氧空位跃迁进行了研究。 通过模拟MO掺杂的氧化铈基电解质缺陷行为研究发现,通过氧空位电荷补偿缺陷形式,与Sr²⁺,Ba²⁺,Mg²⁺相比Ca²⁺固溶能低:CeO₂晶格常数随着CaO、SrO、BaO掺杂量的增加而增加,随着MgO掺杂量的增加而减少;Ca²⁺与氧空位形成[M″_Ce·V_?]^×缺陷对的束缚能最低;带电缺陷体[V_?·M″_Ce·V_?]¨在CeO₂中是不稳定结构,中性缺陷体[V_?·M″_Ce·V_?·M″_Ce]^×是稳定存在的缺陷结构;氧空位在次近邻间的跃迁能最低,因此最容易实现跃迁。通过模拟M₂O₃掺杂的CeO₂基电解质材料的缺陷行为发现,在三价离子固溶于CeO₂反应中,掺Gd³⁺的固溶能低,掺Al³⁺的固溶能比稀土元素高;随着Gd₂O₃、La₂O₃掺杂量的增加,CeO₂晶格常数增加,Y₂O₃与之相反;氧空位趋向位于半径比Gd³⁺小的掺杂离子的第一近邻位置,而对于比Gd³⁺半径大的离子,氧空位位于其第二近邻位置,掺杂离子Gd³⁺和氧空位的结合能最大,Al³⁺与氧空位的结合能最小;掺杂Al³⁺离子时,氧空位跃迁能比掺稀土离子的高。因此掺杂稀土氧化物可以有效地提高导电率。 采用固相反应法制备掺杂的氧化铈电解质材料。掺杂Gd³⁺的电导活化能实验值和本文的理论计算值误差百分数为4%,而掺Ca²⁺的电导活化能实验值和本文的理论值误差较大。更多还原

【Abstract】 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.更多还原