Development of homogeneous solid electrolyte/electrode structureby chemical vapor deposition method

制备燃料电池固体电解质的典型工艺是烧结法。然而，由于原料混合不充分和烧结过程中的局部扩散，以及发电的长时间运行，带来了阳离子的不均匀。这些不均匀性随着三价阳离子掺杂量的增加而增强，例如20-30at%。提出了以Ce(EtCp)4(Ce(C5H4C2H5)4)和Gd(EtCp)3(Gd(C5H4C2H5)3)为源材料的化学气相沉积(CVD)方法。在本研究中，我们确定了用于低压冷壁式CVD装置的CVD工艺的最佳原料条件。我们成功地在Al_2O_3、SiO_2/Si衬底上制备了柱状GDC薄膜。结果表明，在30 0℃左右生长的薄膜为柱状结构，在晶面外无晶界。由于薄膜的厚度较薄，沿平面外几乎没有晶界，交流测量表明，即使在180℃的温度下，氧化物离子也能够扩散。为了快速生长薄膜，研制了一种新型的常压CVD装置。我们还尝试制备了具有致密表面层的多孔电极作为阳极：Ni-GDC和阴极：LaSrCoO_3-GDC。在多孔电极上用低压CVD法制备了GDC薄膜，并尝试在H_2-O_2体系中产生电能。由于发电试验系统尚处于初步阶段，但要实现CVD衍生电解液系统，我们还有几个要点。

Typical fabrication process of making solid electrolyte for the fuel cell is sintering. However it brings the inhomogeneity of cations from the in sufficient mixing of the raw materials and local diffusion during the sintering and also during long time running of power generation. These inhomogeneity is enhanced the large amount of trivalent cation doping, such as 20-30 at%. We proposed the chemical vapor deposition (CVD) using Ce(EtCp)_4 (Ce (C_5H_4C_2H_5)_4) and Gd(EtCp)_3 (Gd(C_5H_4C_2H_5)_3) as the source materials. In this research, we determined the optimum condition of these raw materials for CVD process for low-pressure coldwall-type-CVD apparatus. We succeeded to fabricate the columnar type GDC film on Al_2O_3, SiO_2/Si substrates. It was found that the film was grown at around 300℃ and has columnar structure that means no grain boundary in the out of plane direction. Since thinner thickness of the film and almost no grain boundary along the out of plane direction, oxide ion can be able to diffuse even at 180℃ by AC measurement. New type atmospheric pressure CVD apparatus was developed to grow the film with very fast growth rate. We also tried to fabricated the porous electrodes with dense surface layer for the anode: Ni-GDC and the cathode: LaSrCoO_3-GDC. GDC thin films by low pressure CVD were fabricated on the porous electrodes, and tried to generate the electric power in the H_2-O_2 system. Since the power generation test system is preliminary, but we have several important point to realize the CVD derived electrolyte system.