【摘要】 本文采用高温固相反应法制备了Sn4+掺杂LaNbO4陶瓷粉体,随后对块体的成型及烧结工艺进行优化,对组织结构、导电性能和化学稳定性进行了测试分析,最后利用第一性原理计算对水蒸气条件下的导电机理进行了研究。态密度结果、能谱成分分析及导电性能测试结果显示Sn4+的最适宜掺杂量为0.5~1at.%。当Sn4+掺杂量为0.5at.%时,LaNbO4陶瓷具有最高的电导率,且为纯质子导电机制。LaNbO4陶瓷具有良好的化学稳定性,且Sn元素的掺入未对LaNbO4陶瓷的化学稳定性产生影响。第一性原理计算结果显示水分子在含氧空位的LaNbO4(010)表面上方会自发解离为质子和羟基,且倾向于在氧空位上方发生解离。更多还原

【Abstract】 In the present work,Sn4+-doped LaNbO4 ceramic powders were synthesized through high-temperature solid state reactions. The processing parameters of shaping and sintering were then optimized. The structure,electrical conductivity and chemical stability were also tested and analyzed. And the mechanisms of conductivity under water vapor conditions were studied via first principles calculations. The appropriate concentration of Sn4+ions is determined as 0. 5 to 1 at. % by DOS figures,EDS component analysis and the results of conductivity. When LaNbO4 ceramic is doped with 5 at. % Sn4+ions,it exhibits the highest conductivity as well as the pure protonic conducting mechanism. LaNbO4 has excellent chemical stability,and the introduction of Sn4+ions has no effect on chemical stability. From the results of the first principles calculations,water molecules may dissociate into protons and hydroxyls over oxygen-deficient LaNbO4( 010) surface,and they tend to dissociate over the sites of the oxygen vacancies.更多还原