Standard molar enthalpy of formation of LiUF₅ compound

Knowledge on thermodynamic properties of compounds of LiF-UF₄ system is of immense importance for understanding the behaviour of MSBR fuel. In view of this, thermodynamic stability LiUF₅ has been investigated. The compound was prepared by solid state reaction and characterized by powder XRD and TGDTA techniques. The molar enthalpy of dissolution of LiUF₅ and its constituent components was measured in molten LiF: UF₄ eutectic mixture at 885K employing a high temperature Calvet calorimeter. Combining the experimentally determined values of the reaction enthalpies with the auxiliary data from the literature, the standard molar enthalpy of formation of the compound at 298 K (Δ_fH°₂₉₈) was calculated. The Δ_fH°₂₉₈ of LiUF₅(s) at 298 K was found to be – (2708.69± 8.3) kJ mol^-1. (author)