マテリアル インテグレーション 2011年10月号
特集　複合アニオン化合物の創製と機能


複合アニオン系光触媒を用いた可視光による水の全分解
■著者
東京大学大学院工学系研究科 化学システム工学専攻　教授 堂免 一成

■要約
光触媒を用いた水の水素と酸素への分解は,太陽光から水素エネルギーを得るための人類の夢の技術である.太陽光を有効利用するためには,より長い波長の可視光を利用する必要があるが,このためには酸素と窒素をアニオンにもつ酸窒化物を利用することが効果的であることが最近の研究でわかってきた.水の全分解のための酸窒化物光触媒の開発の経緯と,酸窒化物光触媒の現在の問題点について議論する.



Al,Si酸窒化物蛍光体
■著者
物質・材料研究機構(NIMS)サイアロンユニット 武田 隆史

■要約
Al,Si oxynitride phosphors show excellent blue excitable luminescence property suitable to white light emitting diodes (LEDs). The stable crystal structures applied to high temperature material contribute to low thermal quenching of luminescence. In addition, some Al,Si oxynitride phosphors have unique crystal structure. In this paper we show the luminescence and crystal structure of rare earth or Mn doped Al,Si oxynitride phosphors.



ペロブスカイト型酸窒化物の色調制御
■著者
徳島大学 大学院ソシオテクノサイエンス研究部 森賀 俊広

■要約
We have prepared oxynitride pigments showing various colors by tuning the O/N, Ti/La and Sr/La ratios independently in the perovskite-type (La,Sr)TiO2N. The increase in O/N ratio led to enhancement of bandgap energy, that is, blueshift of the absorption edge, resulting in the color change from reddish orange to white through yellow. The increase in Ti/La ratio lowered the reflectivity in the longer wavelength region after the absorption edge, which could be related with increasing particle sizes of the oxynitride powders. The substitution of La by Sr improved the reflectivity in the longer wavelength region. Especially, in cation-nonstoichiometric oxynitrides with Ti/(La+Sr)>1, the Sr-substitution enhanced the reflectivity in the region just after the absorption edge and efficiently reduced the reflectivity in the red region, probably due to the formation of a lot of anion deficiency. These features have enabled us to produce La-Sr-Ti-O-N oxynitride pigments showing the three primary colors composed of nontoxic and ecological elements.



希土類添加半導体の新展開
■著者
大学院工学研究科マテリアル生産科学専攻　マテリアル科学コース 藤原　康文

■要約
Er,O-codoped GaAs (GaAs: Er,O) is one of state-of-the-art rare-earth doped semiconductors. In GaAs: Er,O grown by organometallic vapor phase epitaxy, one kind of Er center is formed selectively as an Er atom located at the Ga sublattice with two adjacent O atoms (hereafter referred as Er-2O) together with two As atoms, resulting in drastic enhancement of the intensity of Er-2O luminescence due to the intra-4f shell transitions of Er3+ ion. A double-heterostructure light-emitting diode with GaAs: Er,O as an active layer has been successfully demonstrated at room temperature. Furthermore, curious magnetic properties of GaAs: Er,O have been revealed in electron spin resonance measurements.



複合アニオン型可視光応答性光触媒
■著者
東北大学多元物質科学研究所 殷　(シュウ)

■要約
Environmentally friendly soft chemical processes, including solvothermal/hydrothermal process and mechanochemical process, for the synthesis of milti-anion type visible-light induced photocatalysts are introduced in this paper. Titania and strontium titanate based anion doped photocatalysts can be effectively prepared at such low-temperature as below 200℃. Especially, the mechanochemical process is a useful method for the synthesis of various multi-ion doping functional materials at low temperatures. The multi-anion type photocatalytic compounds consisted of N/O, N/F/O, S/O, N/C/O, together with those consisted of various transition metals, such as Nb, Ta, Fe, Cr, and La, show excellent visible light absorption ability and photocatalytic activities, indicating the potential applications of multi-ions consisted compounds in environmental purification.



新規酸窒化物ガラス創製の試み
■著者
長岡技術科学大学　物質・材料系 教授 小松　高行

■要約
The fabrication of new oxynitride glasses based on the AlN, LaN-Bi2O3-B2O3 and LaN-ZnO-B2O3 system was tried by using a conventional melt-quenching method, because the introduction of nitrogen into B2O3-based glasses having low melting temperature is considered as a new glass design for new functionality. In the case of AlN-Bi2O3-B2O3, the precipitation of Bi metals was confirmed and the large increase in the glass transition temperature was observed for the glassy part. It was suggested that AlN acts as a strong reducing substance even in the melting at 1200℃. The reducing ability of LaN is weak compared with AlN. In the case of 5LaN-45ZnO-50B2O3, the glass obtained shows a different DTA pattern and optical absorption spectrum compared with 5LaO3/2-45ZnO-50B2O3 glass, suggesting that some amount of nitrogen would be incorporated into the network of ZnO-B2O3 glass.



機能性酸窒化物における構造形成
■著者
北海道大学工学研究院　物質化学部門　無機材料化学分野 教授 吉川　信一

■要約
Metal nitrides, especially oxynitrides are attracting attention to their interesting properties structurally induced. Giantic dielectric property observed in oxynitride perovskite SrTaO2N is induced by the large tilting of cis-TaO4N2 octaheda along c-axis. Emission color is largely affected by the coordination way of nitride and oxide ions together in oxynitride phosphors. Oxide clusters of Mg, Al or Si can be doped in NbN forming new oxynitride superconductors. Both micro patterning and granule precipitation are possible in nitride thin films applying their thermal metastability.



複合アニオン系新規超伝導物質:鉄オキシニクタイドと関連物質
■著者
東京工業大学応用セラミックス研究所・フロンティア研究センター 細野 秀雄

■要約
The mixed anion crystal LaFeAsO is one of the parent compounds of iron-pnictide superconductors reported in early 2008. The crystal structure of LaFeAsO is compossed of stacking of (Fe2+As3-) conducting layer and (La3+O2-) insulating layer. While stoichiometric LaFeAsO is non-superconducting semi-metal with antiferromagnetic order of iron spin, the superconductivity with transition temperature Tc=26K was induced by electron doping to FeAs layer by partial replacement of oxygen in LaO layer with fluorine (LaFeAsO1-xFx). This discovery rekindled extensive superconductivity research like the fever in high-Tc cuprates in late 1980s, and led to the publications of more than 3,000 papers to date. The highest Tc record (〜55K) of iron-based superconductors was obtained by the replacement of La in LaFeAsO with other lanthanide with smaller ionic radius such as Sm. In this article, we review iron oxy-pnictide LnFeAsO (Ln: lanthanides) and related iron-pnictide with its background research on transition metal pnictides led to the discovery.



複合アニオン化合物とイオン伝導性
■著者
九州大学大学院工学研究院応用化学部門 石原　達己

■要約
複合アニオン化合物では,ハロゲン化合物に代表されるようにAgやCuイオン伝導性を示す超イオン伝導体がよく知られている.近年,アニオンの添加効果が注目されており,添加されたアニオンが伝導する現象が注目されている.とくにオキシナイトライド中の窒素イオン伝導やオキシフッ化物中の酸素イオン伝導など,新しいイオン伝導を示す化合物が報告され,注目されている.



複合カチオン,複合アニオンカルコゲナイドナノ結晶と光機能
■著者
大阪大学大学院　工学研究科マテリアル生産科学専攻 准教授 小俣　孝久

■要約
高輝度で発光する二元系カルコゲナイド半導体のコロイダルナノ結晶の作製方法として,ホットソープ法と呼ばれる方法がある.この方法を用いたCdSeのコロイダルナノ結晶が報告されて以降およそ20年が経過し,ホットソープ法はカルコゲナイドに限らず酸化物やニクタイドなど様々な化合物のコロイダルナノ結晶を作製できる技術へと洗練された.本稿ではこの期間を振り返り,カルコゲナイドのコロイダルナノ結晶において,複数のアニオンやカチオンを含む三元系以上の化合物でどのような光機能が達成されてきたかを概説し,化合物半導体ナノ結晶における複合イオン化による機能開拓の指針を紹介する.



連載
近代日本のセラミックス産業と科学・技術の発展に尽力した偉人,怪人,異能,努力の人々(47)大学卒業後真面目にフッ素雲母の研究一筋に生涯を捧げられ,さらに信州大学の教育面の充実に尽力された信州大学　大門信利教授
■著者
宗宮　重行