Pressure-composition isotherms and thermodynamic properties of TiF3-enhanced Na2LiAlH6

The mixed alanate Na2LiAlH6 was prepared by ball-milling and subsequent heat-treatment under H2 pressure. After the synthesis, 2 mol% TiF3 was added by ball-milling. Pressure-composition isotherms were measured for the Ti-enhanced material in the temperature range of 170-250 °C. A van't Hoff plot was constructed using the equilibrium desorption plateau pressures. From this plot, a dissociation enthalpy of 56.4 ± 0.4 kJ/mol H2 and a corresponding entropy of 137.9 ± 0.7 J/K mol H2 was found for Na2LiAlH6.