Tuning the Intermediate Valence Behavior in the Zintl Compound YbZnSb by Incorporation of RE [YbREZnSb (0.2 ≤ ≤ 0.7), RE = Sc, Y, La, Lu and Gd].

The solid solutions of YbREZnSb (RE = Sc, Y, La, Lu, and Gd; 0.2 ≤ ≤ 0.7) were prepared to probe the intermediate valency of Yb in YbZnSb. The substitution of Yb with RE elements should reduce or remove the intermediate valency of the remaining Yb ions. Large crystals are grown from Sn-flux, and the structure and magnetic susceptibility are presented. All compounds crystallize in the CaAlSb structure type and the RE ions show Yb site substitution preferences that correlate with size. Two compositions of YbYZnSb were investigated [ = 0.38(3), 0.45(3)] by temperature-dependent magnetic susceptibility and the broad feature in magnetic susceptibility measurements at 85 K in pristine YbZnSb attributed to valence fluctuation decreases and is absent for = 0.45(3). In compounds with nonmagnetic RE substitutions (Sc, Y, La, and Lu), temperature-dependent magnetic susceptibility shows a transition from intermediate valency fluctuation toward temperature-independent (Y, La, and Lu) or Curie-Weiss behavior and possibly low temperature heavy Fermion behavior (Sc). In the example of the magnetic rare earth substitution, RE = Gd, the Curie-Weiss-dependent magnetic moment of Gd is consistent with . Hall resistivity of YbYZnSb showed that the carrier concentration decreases with and the signature of the low-T intermediate valence state seen for = 0 is suppressed for = 0.38 and gone for = 0.45.