Reactions between sodium carbonate and vanadium pentoxide

The isothermal reactions between Na₂CO₃(X) and V₂O₅(Y) have been studied. It has been noticed that the reaction depends on both temperature and the molar X:Y ratios for the mixtures 1:6 and 1:3. For higher Na₂CO₃ contents, the reaction is more dependent on temperature. An X-ray examination of the isothermal products revealed the sequence of formation of different types of vanadates. The X-ray diffraction patterns for five sodium vanadates were investigated. The presence of two types of bronze I; Na₂V₁₂O₃₁ and NaV₆O₁₅ was evidenced by both X-ray and differential thermal analysis. The transformation of the former compound to the latter during cooling is accompanied by oxygen evolution; a phenomenon which is reversible.