Intermediate Yb valence in the Yb₁₄MSb₁₁ (M = Zn, Mn, Mg) phases

Crystal structure and plots of figure of merit

The Yb₁₄MSb₁₁ (M = Zn, Mn, Mg, referred to as 14-1-11) system is often recognized for its great thermoelectric efficiency at high temperature.  The Kauzlarich group (Allan He, Elizabeth L. Kunz Wille) in collaboration with LBNL (Lawrence Berkeley National Laboratory) and LANL (Los Alamos National Laboratory), have revealed the intermediate valence nature of Yb in the 14-1-11 system from low temperature magnetic property measurements, heat capacity, and XANES (X-ray Absorption Near-edge Structure) on single crystal samples.  The differences in d-orbital contribution (Mg = d, Mn = d, Zn = d¹⁰) to the bonding in the 14-1-11 system lead to unique physical phenomenon in each compound, in particular revealing a Schottky anomaly and Kondo behaviour in the M = Mg system and temperature dependent intermediate valence behaviour in M = Zn. 

For more, see: https://journals.aps.org/prmaterials/pdf/10.1103/PhysRevMaterials.4.114407