The structural changes and water behaviors in hydrous amorphous silica materials under high pressure and temperature

13301甲第4057号博士（理学）金沢大学博士論文本文Ful

Structural characterization of the body frame and spicules of a glass sponge

金沢大学理工研究域自然システムThe nanostructure (atomic-scale structure) and water species in the body frame and spicules of the marine glass sponge, Euplectella aspergillum, collected from the sea floor around Cebu Island was characterized in detail by thermogravimetric differential thermal analysis, nuclear magnetic resonance spectroscopy, Raman and infrared spectroscopies, and X-ray diffraction method. The structural features of the nanostructure in the body frame and spicules were essentially similar to each other, although these were different from those of inorganic amorphous silica materials, such as silica gel and silica glass. In addition, the averaged short and medium range structures of the sponge may be similar to those of tridymite. The water content and water species included in the body frame and spicules were almost the same. More than half of the contained water was physisorbed water molecules, and the rest was attributed to Q3 and Q2 silanol groups. Most of the water species may be present at the surface and involved in hydrogen bonding

研究基盤EXPO2024シンポジウム 会議録「私立大学の戦略的コアファシリティ2024～私立大学が整備する多様なコアファシリティの役割りと意味、産官との連携～」

目次: 開会挨拶 / 来賓挨拶 /シンポジウムの趣旨説明 / 話題提供「東京理科大学の戦略的コアファシリティ」 / 話題提供「東海大学の戦略的コアファシリティ」 / 話題提供「早稲田大学の戦略的コアファシリティ」 / パネルディスカッション / ご講評 / 閉会挨拶 / 付録1事後アンケート結果2024年1月24日研究基盤 EXPO2024シンポジウム 主催︓早稲田大学 共催︓東京理科大学東海大学 一般社団法人日本分析機器工業会(JAIMA)一般社団法人研究基盤協議会(CORE)conference proceeding

Structural change of the frustule of diatom by thermal treatment

Abstract The external skeleton, frustule, of a diatom is composed of hydrous amorphous silica and amino acids. In this study, the structural changes in the frustule of Chaetoceros calcitrans after thermal treatment up to 1200 °C were investigated using X-ray diffraction and attenuated total reflection infrared spectroscopy and Raman spectroscopy. Their structural changes after thermal treatment give important information to elucidate the unheated structure of the frustule and its crystallization process. In addition, this study is almost the first report to discuss the structure of diatom frustule in detail with Raman spectrum. The unheated structure of the frustule has the relatively ordered and dominant six-membered ring structure made of SiO4 tetrahedra. The sample heated at 800 °C has the more ordered six-membered ring structure observed in quartz or cristobalite. Water molecules and silanol (Si–OH) included in the frustule are dehydrated at this temperature. This dehydration may promote the formation of ordered and polymerized structure. The structure of the frustule after heating at 1200 °C is similar to that of low-cristobalite. However, additional heating is required for complete crystallization

Structural Characterization of the Body Frame and Spicules of a Glass Sponge

The nanostructure (atomic-scale structure) and water species in the body frame and spicules of the marine glass sponge, Euplectella aspergillum, collected from the sea floor around Cebu Island was characterized in detail by thermogravimetric differential thermal analysis, nuclear magnetic resonance spectroscopy, Raman and infrared spectroscopies, and X-ray diffraction method. The structural features of the nanostructure in the body frame and spicules were essentially similar to each other, although these were different from those of inorganic amorphous silica materials, such as silica gel and silica glass. In addition, the averaged short and medium range structures of the sponge may be similar to those of tridymite. The water content and water species included in the body frame and spicules were almost the same. More than half of the contained water was physisorbed water molecules, and the rest was attributed to Q3 and Q2 silanol groups. Most of the water species may be present at the surface and involved in hydrogen bonding