Part of molybdenum introduced in SnO2 by various methods is found to be stabilized in the pentavalent state at substitutional positions. The ESR spectra of Mo5+ ions are characterized by the following parameters: gxx = 1.891; gyy = 1.835 and gzz = 1.923, Axx = 24 G, Ayy = 30 G and Azz = 70 G. There are, in addition, two sets of superhyperfine structures due to the two tins located along the crystallographic c axis (290 G) and to the four tins lying in a diagonal plane of the unit cell containing four oxygens (51 G), consistent with a 3dx2-y2 + λ 3dz2 ground state. The variations of the Mo5+ ESR spectrum upon heating the samples in various atmospheres (O2, H2) suggest that molybdenum enters the SnO2 lattice also as Mo4+. © 1975.
Meriaudeau, P., Che, M., & Tench, A. J. (1975). Paramagnetic absorption of pentavalent molybdenum in polycrystalline tin dioxide. Chemical Physics Letters, 31(3), 547–550. https://doi.org/10.1016/0009-2614(75)85082-2