The phase diagram and phase transition of the V2O3−V2O5, system

The phase relation in the V2O3−V2O5 system and the homogeneity range of each Magnéli phases were re-examined by magnetic and differential thermal analyses, in addition to the usual X-ray analyses. In particular, this report aimed to clarify the nature of the phase transition in the homologous series VnO2n−1. The Mössbauer effect measurements revealed that the phase transformation in V4O7 and V5O9 is a transition from paramagnetic to paramagnetic, namely merely a crystallographic transformation. The origin of phase transition of vanadium oxides including VO2 and V2O3 is discussed on the basis of the d-electron pairing model proposed by Goodenough.