Synthesis and study of high-temperature heat capacity of erbium orthovanadate

Orthovanadate ErVO4 has been prepared by solid-phase synthesis from a stoichiometric mixture of high pure V2O5 and chemically pure Er2O3 by multistage calcination in air in the temperature range 873–1273 K. The effect of temperature (380–1000 K) on the heat capacity of orthovanadate ErVO4 was studied by hightemperature calorimetry. Thermodynamic properties of erbium orthovanadate (enthalpy change H°(T)–H°(380 K), entropy change S°(T)–S°(380 K), and reduced Gibbs energy Φ°(T)) have been calculated from the experimental C p = f(T) data. It has been shown that the specific heat varies in a row of oxides and orthovanadates of Gd-Lu naturally depending on the radius of the R3+ ion within the third and fourth tetrads.