Tuning the Intermediate Valence Behavior in the Zintl Compound Yb 14 ZnSb 11 by Incorporation of RE 3+ [Yb 14- x RE x ZnSb 11 (0.2 ≤ x ≤ 0.7), RE = Sc, Y, La, Lu and Gd].

The solid solutions of Yb 14- x RE x ZnSb 11 (RE = Sc, Y, La, Lu, and Gd; 0.2 ≤ x ≤ 0.7) were prepared to probe the intermediate valency of Yb in Yb 14 ZnSb 11 . The substitution of Yb with RE 3+ 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 Ca 14 AlSb 11 structure type and the RE 3+ ions show Yb site substitution preferences that correlate with size. Two compositions of Yb 14- x Y x ZnSb 11 were investigated [ x = 0.38(3), 0.45(3)] by temperature-dependent magnetic susceptibility and the broad feature in magnetic susceptibility measurements at 85 K in pristine Yb 14 ZnSb 11 attributed to valence fluctuation decreases and is absent for x = 0.45(3). In compounds with nonmagnetic RE 3+ 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 3+ is consistent with x . Hall resistivity of Yb 14- x Y x ZnSb 11 showed that the carrier concentration decreases with x and the signature of the low-T intermediate valence state seen for x = 0 is suppressed for x = 0.38 and gone for x = 0.45.