STUDY OF THE EVOLUTION OF CACO3-V2O5 (1-1) MIXTURE AT ROOM-TEMPERATURE BY THERMAL-ANALYSIS

Reactivity of solid mixtures of crystalline V2O5 and basic compounds strongly increases at room temperature by means of water molecules adsorption process from a saturated atmosphere (100% RH). This is due, to a crystalline-amorphous V2O5 transformation and secondly to the formation of strongly acid V2O5 gels. In the present paper the evolution with time of the CaCO3-V2O5 (1:1) mixture in the aforementioned conditions was studied by thermal analysis (TG, DTG and DSC), X-ray diffraction (XRD) and infrared spectroscopy (IR). The results confirmed the V2O5 gels formation which decomposed the basic CaCO3 at room temperature through an acid-base mechanism reaction. A new crystalline compound was obtained which corresponded to a hydrated calcium metavanadate.