Détermination des chaleurs de formation des orthovanadates de certains éléments des terres rares par la méthode d'analyse thermique différentielle

The heats of formation of LnVO₄-type salts (whereLn=Y, La, Sm, Nd, Gd and Dy) were determined by thermal analysis in the reactions of melts of stable lanthanides and V₂O₅ in a 1 ∶ 1 mole ratio. Heats of formation of LnVO₄-type salts can be determined using non-stoichiometric mixtures of the substrates as well. With the aid of DTA the apparent activation energies of the syntheses of the orthovanadates of these lanthanides were calculated.