The structural diversity and properties of NbxMo1-xO2

We synthesized NbxMo1-xO2 series compounds and determined the structure of each component through x-ray diffraction and selected area electron diffraction techniques. For x=0.05, 0.1, 0.2, they possess room temperature MoO2 monoclinic structure (P21/c); for x=0.25, 0.3, they become to body-centered tetragonal structure (I41/a); for x=0.33, 0.6, 0.65, they further turn to TiO2 rutile-type structure (P42/mnm). Nb0.25Mo0.75O2 has transport and magnetic properties similar to those of NbMoO4 as paramagnetic metal. Moreover, the UV–vis spectra indicate the metallic property of Nb0.05Mo0.95O2, Nb0.25Mo0.75O2, and Nb0.6Mo0.4O2. X-ray absorption spectra at the Mo-L3 and Nb-L3 edges present Mo4+/Nb4+ and Mo4+/Nb5+ valence state for Nb0.25Mo0.75O2 and Nb0.05Mo0.95O2, respectively. This means the latter can be descripted as Nb0.05Mo0.95O2+δ with δ = 0.025.