Hydrogen isotope absorption in Zr(Mn_0.5Fe_0.5)₂

The absorption capacities and rates of hydrogen and deuterium in Zr(Mn_0.5Fe_0.5)₂ are determined in the range of 5 kPa<p_H(2)·p_D(2)<100 kPa and 273 K<T<473 K by means of a constant volume method. The Sieverts' law holds good in almost the whole range of the Zr(Mn_0.5Fe_0.5)₂-H₂ and -D₂ system. The isotopic difference in solubility between H and D becomes smaller with an increase in temperature. The relative partial molar enthalpy per gram atom of H is slightly smaller than that per gram atom of D. The absorption rates of H₂ and D₂ are not explained by previous hydrogenating rate equations but are correlated to a unique dissociation-relating-reaction rate equation regardless of temperature, initial hydrogen pressure and isotopic species. The reaction rates of H₂ and D₂ are characterized in terms of the time to fill half of the equilibrium absorption amount of the Zr(Mn_0.5Fe_0.5)₂ particles. The half time is a linear function of the reciprocal of temperature independent of the initial pressure.