Thermochemistry of oxide bronzes. Part I. Sodium vanadium bronzes NaxV2O5 with x between 0·2 and 0·33

Abstract

The enthalpies of formation from Na(s) and V₂O₅(s) of five β-phase sodium vanadium bronzes Na_xV₂O₅(s) in the range 0·20 ⩽x⩽ 0·33 have been determined by solution calorimetry. The partial molar enthalpy of solution of Na(s) into V₂O₅(s) is constant over the composition range investigated. The thermodynamic stability of the β-bronze phase towards oxidation and disproportionation is discussed.