Abstract
Chemical preparation, thermal behavior, kinetic and IR studies are given for the cyclotriphosphate Ca3(P3O9)2•10H2O. Ca3(P3O9)2•10H2O is monoclinic P21/n with the following unit-cell dimensions: a = 9.332(7)Å, b = 18.13(1)Å, c = 7.841(5), β = 106.69(5)° and Z = 2. Ca3(P3O9)2•10H2O has never been studied except for its crystallographic characterization. The thermal behavior of Ca3(P3O9)2.10H2O has been studied and interpreted by comparison with IR absorption spectrometry, X-ray diffraction experiments, chemical analyses, thermal analyses (TGA-DTA) and differential scanning calorimetry (DSC). Ca3(P3O9)2•10H2O is stable, in the conditions of temperature and pressure of our laboratory, until 80°C. It is impossible to dehydrate Ca3(P3O9)2•10H2O without breaking its rings P3O93- and leading to amorphous compounds in X-ray diffraction and IR absorption spectrometry. The final product of the dehydration and calcination of Ca3(P3O9)2•10H2O, under atmospheric pressure is its long chain polyphosphate form β, β[Ca(PO3)2]8. β[Ca(PO3)2]8 is stable until its melting point at 1097°C. On the other hand, β[Ca(PO3)2]8is prepared by dry way. β[Ca(PO3)2]8 has many applications in industry such as humidity sensor and corrosion inhibitor. Also, quantum chemical calculations have been performed for the P3O9 rings.
