Formation and Transformation of δ-Ta2O5 Solid Solution in the System Ta2O5-Al2O3 |
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Authors: | Osamu Yamaguchi Daijo Tomihisa Tatsuji Uegaki Kiyoshi Shimizu |
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Affiliation: | Department of Applied Chemistry, Faculty of Engineering, Doshisha University, Kyoto 602. Japan |
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Abstract: | In the system Ta2O3-Al2O5 solid solutions of metastable δ-Ta2O5 (hexagonal) are formed up to 50 mol% Al2O3 from amorphous materials prepared by the simultaneous hydrolysis of tantalum and aluminum alkoxides. The values of the lattice parameters decrease linearly with increasing Al2O3, content. The to β-Ta2O5 (orthorhombic, low-temperature form) transformation occurs at ∼950°C. The solid solution containing 50 mol% Al2O3 transforms at 1040° to 1100°C to orthorhombic TaAlO4. Orthorhombic TaAlO4 contains octahedral TaO6 groups in the structure. |
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