E.P.R. evidence of sodium clustering in NaxV2O5-β

The β-phase of the vanadium bronzes Na_xV₂O₅ has been studied by E.P.R. as a function of x(0.21 ? x ? 0.33). The behaviour of the spin E.P.R. susceptibility is in agreement with the hypothesis of a complete transfer of electrons from sodium to vanadium sites. In addition, the dependence on sodium concentration indicates that the sodium atoms are not randomly distributed when x < 0.33.