The contribution of valence unstable ytterbium states into kinetic properties of YbNi2−xGe2+x and YbCu2−xSi2+x

The intermetalic YbNi2−xGe2+x (−0.25 ≥ x ≥ 0.25) and YbCu2−xSi2+x (−0.20 ≥ x ≥ 0.20) alloy systems (CeGa2Al2 -type crystal structure) were studied by measuring X-ray absorption and diffraction at room temperatures as well as electrical resistivity and thermopower in the 4.2–300 K temperature range. The temperature dependence of the contribution of valence unstable Yb ions to the total electrical resistance has been analyzed. The qualitative estimation of this contribution has been performed by utilizing the following equation:ΔρYb(T)=ρexp(T)−ρYbCu2Ge2(T)−Δρ4.2 K,where ΔρYbCu2Ge2(T) is the temperature dependence of YbCu2Ge2 electrical resistance, Δρ4.2 = ρ4.2(exp) − ρ4.2(YbCu2Ge2).