Experimental and theoretical study of hydrogen absorption by LaNi3.6Mn0.3Al0.4Co0.7 alloy using statistical physics modeling

A monolayer model treated by statistical physics by means of the grand canonical ensemble has been developed, describing PCT isotherms for absorption of hydrogen by LaNi3.6Mn0.3Al0.4Co0.7 alloy. This model presents a high correlation with the experimental results. The experimental absorption isotherms are fitted at three temperature different (T = 293 K to T = 313 K). The physicochemical parameters involved in the model were determined from the experimental isotherms by numerical simulation. These parameters, such as two numbers of absorbed atoms per site n1 and n2, two receptor site densities N1M and N2M, and two energetic parameters, P1 and P2 are discussed in relationship with absorption process. The different thermodynamic functions which govern the absorption mechanism such as entropy (Sa), free enthalpy of Gibbs (G) and internal energy (Eint) are derived by statistical physics model calculations.