<p> The crystal structures of five ternary oxides and fluorides have been determined. It is shown that the gross features of these structures and the coordination of the atoms can be described in terms of the theory of close-packing of spheres. However, in each of the structures there appear cations whose coordination cannot be uniquely predicted, as the cation-anion radius ratios are close to the critical value for transition from one coordination to another.</p> / Thesis / Doctor of Philosophy (PhD)

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18982号 / 工博第4024号 / 新制||工||1620 / 31933 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 酒井 明, 教授 邑瀬 邦明 / 学位規則第4条第1項該当

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18982号 / 工博第4024号 / 新制||工||1620(附属図書館) / 31933 / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 田中 功, 教授 酒井 明, 教授 邑瀬 邦明 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

In this research, a temperature dependent tribological investigation of selected ternary oxides was undertaken. Based on the promising results of previous studies on silver based ternary oxides, copper based ternary oxides were selected to conduct a comparative study since both copper and silver are located in the same group in the periodic table of the elements. Two methods were used to create ternary oxides: (i) solid chemical synthesis to create powders and (ii) sputtering to produce thin films. X-ray diffraction was used to explore the evolution of phases, chemical properties, and structural properties of the coatings before and after tribotesting. Scanning electron microscopy, Auger scanning nanoprobe spectroscopy, and X-ray photoelectron spectroscopy were used to investigate the chemical and morphological properties of these materials after sliding tests. These techniques revealed that chameleon coatings of copper ternary oxides produce a friction coefficient of 0.23 when wear tested at 430 °C. The low friction is due to the formation of copper tantalate phase and copper in the coatings. All sputtering coatings showed similar tribological properties up to 430 °C.