Hydrothermal analcime synthesis at 10 MPa isobar

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AbstractHydrothermal analcime synthesis at 10 MPa isobar and 100, 200, and 300 °C isotherms was performed. As synthesis initial components the minerals nepheline, albite, natrolite, jadeite, wairakite and the mixtures nepheline + albite and nepheline + natrolite were used. 1 M Na2SiO3, 1 M NaCl and 0.1 M NaOH (pH = 14, 7, 13) solutions were applied as the hydrothermal medium. On evaluating the synthesis products by means of X‐ray diffraction analysis and X‐ray microanalysis (EDAX) it was estimated that different analcime structural modifications originate especially at temperatures above 200 °C in neutral and alkaline medium from all the mentioned minerals. Analcime with a higher symmetry of the unit cell of crystals form at temperatures above 250 °C particularly.