CsF-LiF equilibrium phase diagram. Phases at equilibrium for the chemical system CsF-LiF are shown as a function of chemical composition (mole percent LiF) and temperature at atmospheric pressure (1 bar). There are three stoichimetric solid phases. Each melts congruently. There are two eutectics, one between CsF and (Cs0.5Li0.5)F at 40 mole % LiF, and one between (Cs0.5Li0.5)F and LiF at 52.5 mole % LiF. Note that the intermediate phase is written as (Cs0.5Li0.5)F, not CsLiF2 so that the mole % values using the lever rule are correct. One mole of CsLiF2 is two moles of (Cs0.5Li0.5)F (see Brady and Stout, 1982). This diagram is based on the collection of alkali halide phase diagrams by Sangster and Pelton (1987).