Thermodynamic characterization of new palladium alloy tritides

The decay of tritium in a metal tritide generates ³He in the lattice which tends to degrade the performance of the material over time. It is desired to develop a material which minimizes the tritium aging effects and may be tailored to a particular tritium processing application. Pd alloys with Ni and Co have been investigated, as Pd tritide is known to be resistant to tritium aging effects and alloying provides a means for adjusting the plateau pressure of the metal tritide. Sets of tritium desorption isotherms were acquired at temperatures between 273 and 338 K over the pressure range of 1-900 kPa. The thermodynamic parameters of ΔH and ΔS for the β-α phase transition of the metal tritides were determined across the plateau regions of the pressure-composition-temperature curves. The average values of ΔH (kJ mol^-1 T^-1) and ΔS (J K^-1 mol^-1 T^-1) were found to be 15.8 and 50.1 for Pd(2.8 wt.%)Ni, 13.7 and 50.3 for Pd(5.2 wt.%)Ni, 15.9 and 51.3 for Pd(2.8 wt.%)Co, and 13.6 and 51.8 for Pd(5.2 wt.%)Co, respectively.