Structural and thermodynamical investigations of La0.23Ni0.34Co0.33Nd0.08Ti0.01Al0.01 hydrogen storage alloy

Hydrogen storage properties of the La0.23Ni0.34Co0.33 Nd0.08Ti0.01Al0.01 have been systematically studied in the present work. Pressure composition ( P – C – T ) isotherm has been investigated in the temperature and pressure ranges of 308 ⩽ T ⩽ 338 K and 10 ⩽ P ⩽ 140 psi , respectively. The studies show the presence of two single α and β phases with one mixed α + β phase. The maximum H / M ratio was found to be around 0.94 at 308 K and 90 psi. The introduction of interstitial hydrogen particles into a metallic lattice causes several changes in respect to its electrical resistance. Hence an attempt has been made to relate change in the resistance of material with the content of hydrogen. The resistance of the specimen was found to increase with increasing H / M . Thermodynamical parameters viz., the relative partial molar enthalpy ( Δ H ) and relative partial molar entropy ( Δ S ) of dissolved hydrogen are found to be 14.50755 ± 0.8 K J / mol H 2 and 47.01152 ± 2.42 J / K / mol H 2 , respectively. The variation of enthalpy and entropy with hydrogen concentration has also been calculated to confirm the existence of different phases.