FLiBe is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2). FLiBe is a highly researched nuclear based coolant that can be used in LENR cavatation. FLiBe cavitation erosion rate were found to be 10X greater than water: this is very good for LENR cavitation.
The 2:1 mixture forms a stoichiometric compound, Li2BeF4, which has a melting point of 459 °C, a boiling point of 1430 °C, and a density of 1.94 g/cm3. Its volumetric heat capacity is 4540 kJ/m3K, which is similar to that of water, more than four times that of sodium, and more than 200 times that of helium at typical reactor conditions. Its appearance is white as a solid to transparent when a liquid, with crystalline grains in a solid state, morphing into a completely clear liquid upon melting.
The eutectic mixture is slightly greater than 50% BeF2 and has a melting point of 360 °C. This mixture was never used in practice due to the overwhelming increase in viscosity caused by the BeF2 addition in the eutectic mixture. BeF2, which behaves as a glass, is only fluid in salt mixtures containing enough molar percent of Lewis base. Lewis bases, such as the alkali fluorides, will donate fluoride ions to the beryllium, breaking the glassy bonds which increase viscosity. In FLiBe, beryllium fluoride is able to sequester two fluoride ions from two lithium fluorides in a liquid state, converting it into the tetrafluorberyllate ion BeF4−2.
Liquid flibe flowing in a quartz pipe (courtesy of ORNL) - melting point is 460 C
Quartz pipe can be used to allow laser beam access to the FLiBe.
Hydrogen is introduced into the FLiBe through bubbling a 1:1 mixture of hydrogen fluoride and hydrogen through the salt. Some of structural materials used in conjunction with FLiBe are tungsten, carbon, molybdenum, platinum, iridium, and nickel.