Antiferromagnetism induced by oxygen vacancies in V sub(2)O sub(5) polycrystals synthesized by the Pechini method

Optical and magnetic properties of V sub(2)O sub(5) polycrystals were investigated through photoluminescence (PL) and magnetization measurements. The PL spectra comprise two main bands attributed to oxygen vacancies and to band-edge-related transitions. The magnetization measurements showed a predominant paramagnetic behavior in the temperature range studied (5 K-300 K) with a superimposed peak around 80 K associated with an antiferromagnetic phase. The temperature dependence of the magnetic results and the relative PL intensity presented a remarkable correlation while in the range of 80-200 K the intensity associated with oxygen vacancies became considerably more intense than band-to-band emissions, the same range in which the antiferromagnetic transition was observed. The observation of an antiferromagnetic phase in V sub(2)O sub(5) was predicted in the literature although this result had not previously been measured experimentally. Raman spectroscopy was used as a complementary technique in order to exclude the presence of spurious vanadium oxide phases in the sample.