New critical point at the vicinity of the freezing temperature of K2Cs

The density, heat capacity, and electrical resistivity for the alloy K-Cs at the stoichiometric composition K2Cs have been measured through the solid and liquid states. A new singular point Tc=258 K has been detected above the well-known freezing point T=253.5 K. This is the rare case of a critical point being close to the solidification transition and is also the only case known of a miscibility gap in the liquid state of a mixture that exhibits full solubility below its solidus line.