Ion Dynamics at Interfaces on Nano-structured Ion Conducting Artificial Lattices

固体氧化物燃料电池（SOFC）等高温能量转换系统在高效能源系统中具有巨大的潜力。然而，在广泛的应用领域中，实际应用存在几点问题。本研究利用人工超晶格结构来控制固态电解质材料的界面性质。此外，本文还利用Kelvin探针力显微镜对导电陶瓷的界面进行了研究，以明确晶界性质与导电性之间的关系。主要研究结果如下：（1）以有序阳极多孔氧化铝膜为掩模，采用SF_6快原子束刻蚀技术制备了纳米结构的钙钛矿型质子导电薄膜。在MgO（110）衬底上激光烧蚀沉积SrCeO_3薄膜，得到了100和500 nm周期的六方结构。从X射线衍射分析中发现，垂直于衬底表面的晶格常数a随着纳米结构的周期性减小而减小。透射光谱和反射光谱显示出表面浮雕光栅结构的典型特征。(2)采用Kelvin探针力显微镜在不接触样品的情况下测量了被认为是固体氧化物燃料电池（SOFC）阳极材料的Nb掺杂SrTiO_3的单个晶界的表面电位。系统地研究了表面势与晶界性质的关系，发现随机晶界处的表面势与其它晶界类型有很大的不同。

High temperature energy conversion systems for example solid oxide fuel cells (SOFC) etc have great potentials for high efficiency energy systems. However, there are several points of problems for practical application in wide application fields. In this study, the interface properties of solid state electrolyte materials is controlled by fabricating the artificial superlattice structures. Furthermore, the interface of ceramics of electrical conducting materials is also investigated by Kelvin probe force microscopy, in order to clear the relationship between the grain boundary natures and electrical conductivity. The following results are obtained;(1) Nano-structured perovskite-type proton conducting thin films have been fabricated by SF_6 fast atom beam etching, with an ordered anodic porous alumina membrane as a lithographic mask. 100 and 500 nm period hexagonal structures are patterned on laser ablation deposited SrCeO_3 film on MgO (110) substrate. It is found from x-ray diffraction analysis that the lattice constant a, which is perpendicular to the substrate surface, decreases with decreasing periodicity of the nano-structure. The optical transmission and reflection spectra show typical features of surface-relief grating structures.(2) Surface potential of individual grain boundaries of Nb-doped SrTiO_3 which has been considered a candidate of anode material of SOFC are evaluated by Kelvin probe force microscopy, without contacting to sample. Systematically investigation of the relationship between surface potential and grain boundary character, it is found that the surface potential at random boundary is quite different from other gain boundary types.