1) Metal halide 
FLiBe is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2). It is both a nuclear reactor coolant and solvent for fertile or fissile material. It served both purposes in the Molten-Salt Reactor Experiment (MSRE). The 2:1 mixture forms a stoichiometric compound, Li2BeF4, which has a melting point of 459 °C, a...