Natural and synthetic samples of analcime and pollucite (both zeolites belonging to the analcime group) were studied by means of micro-Raman spectrometry, X-ray fluorescence analysis (XFA) and X-ray diffraction (XRD). On knowing the chemical and structural characteristics of each solid-solution member, the observed shift in the spectral position of the Raman active modes can be explained and used for phase determination. As shown, the distinction between members of the analcime-pollucite solid-solution series using Raman spectroscopy is significantly more conclusive than the corresponding XRD findings. Also, information about the structurally bound water inside the zeolite structure can be gained using Raman spectroscopy as long as a suitable exciting wavelength is selected.

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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.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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