Palladium-tritium system

First measurements of the pressure-composition-temperature relationship for the palladium-tritium system are reported for the pressure range $0.1<~p<~2$. bar, the composition range $0.02<~x<~0.65$ (for $x$ in $\mathrm{Pd}{\mathrm{T}}_x$), and temperature range $35<~T<~125°$C. The PdH and PdD systems have also been measured using the same sample under the same experimental conditions. The main conclusions are that $p_{{\mathrm{T}}_2}>p_{{\mathrm{D}}_2}>p_{{\mathrm{H}}_2}$ at equal concentrations and temperatures, $x_{\mathrm{T}}<x_{\mathrm{D}}<x_{\mathrm{H}}$ at equal pressures and temperatures, and that the $\beta \to \alpha$ transition enthalpies show a strong, and the entropies a negligible, isotope dependence.