Abstract

The ternary compound YbRh1.4Sn4.6 with the phase I structure when subjected to a pressure of 40 kbar at 800°C is found to transform to phase III structure with the composition YbRh1.1Sn3. The latter compound has a lattice parameter of a = 13.735 A ̊ which suggests that the Yb is in an intermediate valence state. The temperature dependence of magnetic susceptibility suggests that the Yb is in a homogeneously mixed valence state in the pressure synthesized product. In the phase I structure YbRh1.1Sn4.6 is superconducting at 8.6°K, but in the phase III structure the compound YbRh1.1Sn3 is not superconducting down to 0.9°K. It is suggested that superconductivity and mixed valence are incompatible. © 1981.