Electrical Resistivity in Non-stoichiometric MoO2

MoO (y) with 1.85 a parts per thousand currency signaEuro parts per thousand y a parts per thousand currency signaEuro parts per thousand 2.20 has been studied by X-ray diffractometry and photoemission spectroscopy at room temperature and by electrical resistance as a function of temperature from 2 to 300 K. Although X-ray diffractograms are very similar to the stoichiometric MoO2 with monoclinic structure of the space group P2(1)/c (14), the electrical properties are strongly dependent on the oxygen composition. Samples with y = 1.85 and 1.90 show anomalous behavior in electrical conductivity. Photoemission and X-ray absorption spectroscopy measurements suggest that this anomalous behavior is related to the presence of Mo3+ ions such as in KxMoO2 compound.