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Central European Geology
Authors: Zsófia Pálos, István János Kovács, Dávid Karátson, Tamás Biró, Judit Sándorné Kovács, Éva Bertalan, Anikó Besnyi, György Falus, Tamás Fancsik, Martina Tribus, László Előd Aradi, Csaba Szabó and Viktor Wesztergom

magmatic water contents is the measurement of structural hydroxyl content in nominally anhydrous minerals (NAMs; Aines and Rossman 1984 ; Rossman 2006 ). NAMs can contain structural hydroxyl and molecular water (OH − and H 2 O) in trace amounts ( Johnson

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Abstract  

The thermal decomposition of the ammonium exchanged vermiculite takes place in three steps. A strong correlation exists between the mass loss of ammonia and water suggesting a simultaneous release. It is proposed that proton transfer from the ammonium ion to the hydroxyl units results in this simultaneous release. This behaviour could be explained by a mechanism where a resulting proton, produced by the release of ammonia out of ammonium cation, combines with a structural hydroxyl to form water. Sonication produces a substantial reduction in the particle size of the vermiculite sample. Thus, the macroscopic particle size of the untreated material is drastically reduced to the micrometers range while the structure as assayed by XRD remains unchanged. The particle size reduction produced by the sonication treatment modifies the thermal decomposition profile, mainly the mass percentages of the different steps.

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Journal of Thermal Analysis and Calorimetry
Authors: Yuri Park, Godwin A. Ayoko, Janos Kristof, Erzsébet Horváth and Ray L. Frost

between ambient and 100 °C, second at 135.5 °C, and at 636.3 °C [ 25 ]. From the result, the MMT is relatively stable and it begins to lose structural hydroxyl OH units at 636 °C but will maintain the layer structure up to ∼900 °C [ 26

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determine the concentration of anisotropic structural hydroxyl defects from a number ( n  > 5) of unoriented crystals with reasonable accuracy. This method can only be applied to strongly anisotropic minerals (e.g., olivine, calcite, and quartz), if the

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Journal of Thermal Analysis and Calorimetry
Authors: Yuri Park, Godwin A. Ayoko, Janos Kristof, Erzsébet Horváth and Ray L. Frost

last mass loss step at 636 °C was observed and the peak has been assigned to the dehydroxylation of structural OH units in the clays. Such mass loss at high temperature shows that MMT is relatively stable and the structural hydroxyl OH units maintain

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three endothermic peaks at 89, 173, and 234 °C in the range of 30–400 °C temperature ranges. These peaks corresponded to the removal of adsorbed and interlayer water. The elimination of the structural hydroxyls of the octahedral sheet gives rise to

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