Impurities and electron localization in V2O5 crystals

V2O5 crystals doped with different impurities of the Mn+ (n = 1 to 6) type are investigated by the EPR method. It follows from the experiment that all the paramagnetic defects are connected with the impurities present in the crystals. The main paramagnetic centre in V2O5 is an electron localized on two 51V nuclei. There is no local compensation of its charge and so it easily destroys in the course of oxidation. It is shown by hyperfine structure investigation that the electron states are localized in a wide temperature range (4.2 to 290 K). The substitutional impurity tends to occupy the vanadium positions near the VV pair. A complex paramagnetic centre is created with electron density distribution dependence on the donor‐acceptor characteristics of the cations. This results in the nonequivalence of the electron interactions with different vanadium atoms, in different values of the HFS constants for differently doped crystals, and in different valency of the impurity cations. Centres of this type are locally compensated and therefore stable to oxidation or reduction.