Affiliation: | aInstitute for Energy Technology, Instituttveien 18, P.O. Box 40, Kjeller N-2027, Norway bPhysico-Mechanical Institute of the National Academy of Science of Ukraine, 5 Naukova St., Lviv 79601, Ukraine cThe Studsvik Neutron Research Laboratory, Uppsala University, S-611 82 Nyköping, Sweden |
Abstract: | The Pressure–Composition–Temperature (P–C–T) relations for the LaNiIn, LaNi0.95Cu0.05In and LaNiIn0.98Al0.02–H systems were measured by a volumetric Sieverts’ method at 398–423 K. All isotherms show plateau pressure regions indicating equilibria between two hydride phases. The replacements of Ni by Cu and In by Al affect the P–C–T diagrams, stability of the hydrides, homogeneity regions of the hydrides formed, slope of the isotherms and critical temperatures of the β–γ transition. In addition, the Cu-doping induces a significant hysteresis between the hydrogen absorption and desorption processes. The relative partial molar thermodynamic properties for the studied systems are: ΔHH = −34.6 ± 2.1 kJ (molH)−1, ΔSH = −70.7 ± 3.6 J (K·molH)−1 for LaNiIn–H; ΔHH = −34.1 ± 0.5 kJ (molH)−1, ΔSH = −74.9 ± 1.0 J (K·molH)−1 for LaNi0.95Cu0.05In–H; ΔHH = −33.2 ± 0.8 kJ (molH)−1, ΔSH = −68.3 ± 1.2 J(K·molH)−1 for LaNiIn0.98Al0.02–H. |