Cd 13− x In y Sb 10 ( x ≈2.7, y ≈1.5): An Interstitial‐Free Variant of Thermoelectric β‐Zn 4 Sb 3

Although free from structural disorder , the new intermetallic compound Cd 13− x In y Sb 10 (see figure) displays similarly low thermal conductivity values as disordered thermoelectric β‐Zn 4 Sb 3 with an isostructural framework.Cd 13− x In y Sb 10 ( x ≈2.7, y ≈1.5) was synthesized in the form of mm‐sized crystals from reaction mixtures containing excess cadmium. The intermetallic compound crystallizes in the rhombohedral space group R $\bar 3$ m with a =12.9704(4), c =12.9443(5) Å, V =1886.0(1) Å 3 , Z =3 and is isostructural to thermoelectric β‐Zn 4 Sb 3 and β‐Cd 4 Sb 3 . However, in contrast to these last two compounds Cd 13− x In y Sb 10 is free from interstitial atoms and does not display any temperature polymorphism. The electrical resistivity of Cd 13− x In y Sb 10 is considerably higher than that of Zn 4 Sb 3 and Cd 4 Sb 3 although the temperature behavior remains that of a metal. The thermal conductivity of Cd 13− x In y Sb 10 is low, with room‐temperature magnitudes around 0.8 W m −1  K −1 , which is comparable to disordered or complex structured Cd 4 Sb 3 and Zn 4 Sb 3 .