Comportamento termico di alcuni polimolibdati di potassio
Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 41 (1966) no. 6, pp. 510-520
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The thermal decomposition of 3 K2O·7 MoO3·4 HO (I), K2O·3MoO3·3 H2O (II), K2O·4 MoO3·3 H2O (III) and K2O·8 MoO3·12 H2O (IV), has been studied by means of DTA and TGA curves and IR spectra. The (I) and (II) lose the crystallization water in one stage, the (III) in two stages (2,5 + 0,5 H2O) and the (IV) in 5 stages (10.5 H2O below 140° and 1,5 H2O between 140° and 200°). The activation energies for the various dehydrations have been calculated. The last 1,5 H2O for the (IV) and the 3 H2O for the (III) are very important in the hydrated salt structure, because the irreversible structural alters with the elimination of this type of water. After the dehydration only the (II), and the (III) melt unaltered at 567° and 559° respectively; the (I) decomposes in di and trimolybdate and the (IV) in tetramolybdate and MoO3.
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