Masahiro Kudo

Adsorbed structure of copper and calcium dipivaloylmethanates on SiO2

Abstract Adsorbed states of copper and calcium dipivaloylmethanate [M(DPM)2 (M = Cu, Ca)] complexes on SiO2 are determined by means of infrared (IR) spectroscopy and extended X-ray absorption fine structure (EXAFS). Since the H atom of surface OH moves into the DPM ligands, the structure of the DPM ligand changes into the structure in adsorbed M(DPM)2. No significant changes in the Mue5f8O bond length and the oxygen coordination numbers around M are observed between isolated M(DPM)2 and adsorbed M(DPM)2 by EXAFS. In spite of the difference in the metals included, the complexes adsorb on SiO2 in a basically identical mechanism, where the adsorbates are stabilized by the ligand-surface interaction.

Molecular beam epitaxial growth of superconducting Ba2DyCu3O6.5 thin films at 420 °C using NO2 as an oxidant

A superconducting Ba2DyCu3O6.5 (orthorhombic II phase) thin film is formed on a MgO(100) substrate at 420u2009°C by molecular beam epitaxial growth using NO2 as an oxidant. Metal elements Ba, Dy, and Cu are sequentially supplied from K cells onto MgO(100) at 420u2009°C under a flow of 5×10−5 Pa of NO2. The film gradually cooled in situ under the identical pressure of NO2 shows metallic behavior in the normal state and a Tczero of 50 K. The lattice constant of the c axis is observed at 11.75 A, which is known as an orthorhombic II phase of bulk Ba2DyCu3O6.5. Due to the slow deposition rate, the film thus formed is oriented with the c axis perpendicular to the surface in spite of the low‐temperature growth condition.

Structure and growth mechanism of ultrathin films of Bi cuprates grown by low-temperature MBE

The structure and growth mechanism of a Bi cuprate formed by low-temperature MBE are discussed. Examination of the X-ray diffraction of the ultrathin films revealed that the lattice constants of an ultrathin film of Bi 2201 are affected by the lattice constants of the substrate. The key process of the low-temperature epitaxial growth realized by the usage of NO 2 is also discussed in correlation with the oxidation mechanism of deposited metals with NO 2 examined by X-ray photoelectron spectroscopy.

Observation of the oxygen-ion image on AIN ceramics by SIMS.

二次イオンイメージの解析により,AlNの粒子や粒界におけるO分布の詳細な評価を行い,粒界部Oの存在の有無について検討した.しかし粒子内部と粒界部の,組成と構造の差異に起因するマトリックス効果を正確に把握できないため,存在の有無を断定できなかった.又,微小領域測定に際して,特に問題となるバックグラウンドレベルの寄与増加の影響も,解釈の妨げとなることが明かになった.今後,このようなセラミックス材料から得られるSIMSの情報を正確に評価するために,装置的にはより超高真空化を進めて,バックグラウンドを下げるなどの改善を行うとともに,セラミックス材料それ自身についてのより詳細な情報を集積する必要がある.すなわち,粒界部についても他の分析手法と組み合わせて得られる詳細な知見を基に,検討を行うなど,総合的な対応が必要であると思われる.