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

高温能量转换系统，如固体氧化物燃料电池(SOFC)等，在高效能源系统方面具有巨大的潜力。然而，在广泛的应用领域中，实际应用还存在几个问题。在本研究中，通过制备人工超晶格结构来控制固体电解质材料的界面性质。此外，还用开尔文探针力显微镜研究了导电材料陶瓷的界面，以明确晶界性质与电导率之间的关系。(1)以有序多孔氧化铝膜为掩模，采用SF_6快原子束刻蚀法制备了钙钛矿型纳米质子导电薄膜。在激光烧蚀沉积的MgO(110)衬底上制备了100 nm和500 nm周期的六方结构。X射线衍射分析表明，垂直于衬底表面的晶格常数a随纳米结构周期的减小而减小。光学透射谱和反射谱显示出典型的表面浮雕光栅结构特征。(2)利用开尔文探针力显微镜，在不接触样品的情况下，对SOFC的候选负极材料Nb掺杂的SrTiO_3单晶晶界的表面电势进行了测量。系统地研究了表面势与晶界特性的关系，发现随机晶界的表面势与其他类型的增益晶界有很大的不同。

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.