Development of Coordination Space Controlled Materials and Their Application to Energy Devices

在这个项目中，我们的目标是开发协调空间控制材料，并将其应用于能源设备。我们的重点是1)基于钙钛矿的新型质子导体的发展，2)新型混合（离子和空穴（或电子））导体的发展，以及3)它们在能源设备（如燃料电池）中的应用。我们详细研究了lasco3基钙钛矿（Lal-xSrx）ScO3-δ (x=0.2,0.3)的导电性能，并获得了“电荷载流子图”。该图描绘了主要的载流子（即氧化离子、质子、空穴和电子）域作为温度(T)、氧分压（P(02)）和氢分压（P(H2)）的函数。在600℃下，钙钛矿有望在燃料电池的阴极和阳极条件下作为质子导体。结果表明，相对密度为98.2%的钙钛矿薄陶瓷可用于氢气传感器等。利用粉末x射线衍射和La研究了质子导电钙钛矿（Lal-xSrx）、ScO3-δ (x=0.1, 0.2, 0.3)和混合（=质子和空穴）钙钛矿（La0.8Sr0.2） （Scl-xMnx）03-s (x=0.1, 0.25, 0.5, 0.75) （LSSM）中金属离子的电子态和局域结构。L3-, Sc K-, Mn K-， Sr K- xafs分析。通过比较质子导电钙钛矿的Sr - K-和Sc - K- xanes区域，发现与ScO6八面体配位的H+（或D+）离子的键合（即电子）态会因Sr掺杂量的不同而不同。LSSM的Mn K-XANES区比较表明，LSSM中的Mn离子具有Mn3+/Mn4+混合价态。LSSM的总电导率测量结果（x=0.25 ~ 0.75）表明，主要载流子不是质子，而是空穴和（或）氧化物离子。

In this project we aim to develop coordination space controlled materials and apply them to energy devices. We focus on 1) development of perovskite-based new proton conductors, 2) development of new mixed (= ionic and hole (or electronic)) conductors, and 3) their application to energy devices, e.g. fuel cells. We have investigated in detail the conduction properties of LaScO3-based perovskites, (Lal-xSrx)ScO3-δ (x=0.2,0.3), and obtained the "Charge carrier map". The map depicts predominant charge carrier (i.e. oxide-ion, proton, hole, and electron) domains as functions of temperature (T), oxygen partial pressure (P(02)) and hydrogen partial pressure (P(H2)). It is found that at 600℃, those perovskites are expected to work as a proton conductor both under cathode and anode conditions of fuel cells. Also it was revealed that the thin ceramics of those perovskites with 98.2% relative density could be applied for H2 gas sensor and so on.We have studied the electronic states and local structures of metal ions in proton conducting perovskites (Lal-xSrx)ScO3-δ (x=0.1, 0.2, 0.3) and mixed (= proton and hole) conducting perovskites with LaScO3 basic structure, (La0.8Sr0.2) (Scl-xMnx)03-s (x = 0.1, 0.25, 0.5, and 0.75) (LSSM) by powder X-ray diffraction and La. L3-, Sc K-, Mn K-, and Sr K-XAFS analysis. The comparison of Sr K- and Sc K-XANES regions of the proton conducting perovskites revealed that the bonding (i.e. electronic) states of H+ (or D+) ions, which are expected to be coordinated to ScO6 octahedra, could exhibit difference depending on amount of Sr doped. The comparison of Mn K-XANES regions of the LSSM suggested that the Mn ions in the LSSM would have Mn3+/Mn4+ mixed valence. The results of total electrical conductivity measurements of LSSM (x=0.25-0.75) suggested the predominant charge carrier is not proton but hole and (or) oxide ion.