Molten Salt Synthesis and Characterization of Potassium Polytitanate - Нанотехнологии <!--%IFTH1%0%-->- <!--%IFEN1%0%--> - Каталог файлов - Партнерство Новые исследования и технологии
Molten Salt Synthesis and Characterization of Potassium Polytitanate Ceramic Precursors with Varied TiO2/K2O Molar Ratios Tomas Sanchez-Monjaras, Alexander Gorokhovsky,w and Jose I. Escalante-Garcia Department of Engineering Ceramics, CINVESTAV, Coahuila CP25000, Mexico Semi-crystalline potassium titanates, useful as precursors to produce composite materials and coatings, were synthesized by thermal treatment of powdered TiO2 in molten mixtures of KNO3 and KOH at 4501–5501C. The products obtained had similar structures of laminar crystals, aggregated in particles of about 3 lm of n5TiO2/K2O molar ratio in the range 2.8– 6.0. The value of n could be regulated by the temperature of synthesis, the weight ratio of [KOH]/[KNO3] in the molten salt mixture, and the number of water washing operations. The reduction of the TiO2/K2O molar ratio increased the contents of H2O in the composition of potassium polytitanate, from 5.3 to 11.4 and from 0.2 to 8.6 (wt%) in the adsorbed and structural forms. The thermal treatment of the potassium polytitanate precursors obtained resulted in dehydration and chemical interaction with unreacted TiO2 at 5001–7501C, amorphization at 7501–8501C, crystallization of K2Ti4O9 (in some cases K3Ti8O17) at 8501–10901C, and crystallization of K2Ti6O13 at temperatures 410901C. The mechanisms of the structural transformation and phase evolution were considered as a function of the TiO2/K2O molar ratio in the potassium polytitanate.
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