Chemical Reactions of Ultraphosphate Glasses with Water at Various Temperatures |
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| Authors: | Gérard Palavit Cyrille Mercier Lionel Montagne Michel Drache Yoshihiro Abe |
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| Affiliation: | Laboratoire de Cristallochimie et Physicochimie du Solide, URA CNRS 452, Ecole Nationale Supérieure de Chimie de Lille, 59652 Villeneuve d'Ascq Cedex, France;Department of Materials Science and Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466, Japan |
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| Abstract: | The chemical reactions between P2O5-ZnO-H2O ultraphosphate glasses and water were characterized between room temperature and 500°C, using thermogravimetry, differential scanning calorimetry, X-ray diffraction, and 31P nuclear magnetic resonance. Water adsorption and hydrolysis reactions of the glass leads to the formation of H3PO4 and crystalline ZnH2P2O7 below 200°C. The rate of water adsorption increases, owing to the hygroscopicity of the hydrolysis products of the glass. Devitrification occurs at 250°C via surface reactions. The microstructure of the devitrified glass consists of crystalline Zn2P4O12 and a liquid phase containing hydrolysis products of P2O5 like metaphosphoric acid (HPO3) n. Devitrification is finally followed by water desorption at higher temperatures. |
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