Electronic property changes of η‐Mo4O11 by doping with tungsten, rhenium, and vanadium

For η‐Mo4O11 the temperature dependence of the magnetic susceptibility, the electrical resistivity, the diffuse reflectance spectra in the visible and near infrared range, and the infrared spectra are investigated with regard to both, the deviation from stoichiometric composition and the partial substitution of molybdenum by tungsten, rhenium, and vanadium. With a low tungsten content at T ≈ 109 K a transition to a charge density wave similar to η‐Mo4O11 can be indicated, and for a higher W content a metal‐insulator transition is found. The infrared spectra are a very sensitive method to detect the phase and structural changes of the compounds. The structural changes with a higher tungsten content give a transition from a metallic behaviour to that of a semiconductor. Furthermore, it is concluded that the preferred place for the substitution of molybdenum by tungsten, rhenium, and vanadium is the tetrahedral site in the crystal.