Study of the electronic properties of some ytterbium filled skutterudites by magnetic susceptibility and x-ray absorption and tin-119 Mossbauer spectroscopy

Magnetic susceptibility, ytterbium L-III-edge x-ray absorption and tin-119 Mossbauer spectral measurements have been carried out to probe the electronic structure of ytterbium and tin in the filled or partially filled skutterudite compounds, YbyCo4Sb12-xSnx, over a range of x and y values. The ytterbium valence obtained from the magnetic susceptibility and ytterbium L-III-edge x-ray absorption measurements is in excellent agreement and clearly reveals an evolution from intermediate valence ytterbium for x=0 to nearly divalent ytterbium for x=0.8. This evolution parallels an increase in the unit cell volume and hence in the ytterbium site volume available as the tin content increases. The tin-119 Mossbauer spectral hyperfine parameters indicate, without question, that tin substitutes on the antimony sublattice of the skutterudite structure. Further, the tin electronic configuration is both very similar to that of the antimony in the structure and insensitive to the ytterbium content, y. (C) 2003 American Institute of Physics.