Kinetic studies on leucite precursors

Central European Journal of Chemistry - 2009
Martina Mrázová1, Alexandra Kloužková2, Martina Kohoutková1
1Laboratory of Inorganic Materials, Institute of Inorganic Chemistry of AS CR and ICT, Prague, Czech Republic
2Department of Glass and Ceramics, Institute of Chemical Technology, Prague, Czech Republic

Tóm tắt

Kinetic studies were performed on two types of leucite precursors. These precursors were prepared using a hydrothermal method at 150°C; the reaction time was 1.5 hours. In order to obtain precursors having different amounts of seed the molarity of KOH was changed. These intermediate products were subsequently calcinated from 5 minutes to 72 hours at temperatures of 850°C, 900°C, 950°C, 1000°C and 1050°C. The crystallinities of the powders were calculated by X-ray diffraction analysis. The crystallization curves for the synthesis of leucite exhibited a typical sigmoidal characteristic. Using different kinetic equations it was found that the Avrami-Eroféev model is the most appropriate to describe the experimental data. Using the Avrami-Eroféev model n reaches an average value of 2.9 which is connected with the three-dimensional growth of nuclei. The calculated activation energy of crystallization of leucite was 385 kJ mol-1 for non-seeded precursors and 246 kJ mol-1 for seeded precursors, respectively.

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Central European Journal of Chemistry

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