The Influence of Pr and Nd Substitution on Hydrogen Storage Properties of Mechanically Alloyed (La,Mg)2Ni7-Type Alloys.

The (La,Mg)₂Ni₇-type alloys are candidates for hydrogen storage materials. In this study, mechanical alloying with subsequent annealing under the argon atmosphere at 1123 K for 0.5 h is applied to produce La_1.5−xPr_xMg_0.5Ni₇ and La_1.5−xNd_xMg_0.5Ni₇ alloys (x = 0, 0.25, 0.5, 1). A shaker-type ball mill is used in the study. The objective of the present study is to investigate the influence of the amount of Pr or Nd in the La-Mg-Ni alloy on the electrochemical, hydrogenation and dehydrogenation properties of (La,Mg)₂Ni₇-type materials. The x-ray diffraction analysis reveals the formation of multi-phase structure materials. The obtained alloys were studied by a conventional Sievert’s type apparatus at 303 K. It has been observed that a chemical modification by Pr and Nd can affect the kinetics of the hydrogen absorption process and the maximum hydrogen storage capacity. Moreover, the stability of the electrochemical discharge capacity during cyclic work of the (La,Mg)₂Ni₇-type alloys is improved by a substitution with the La by Pr or Nd atoms. [ABSTRACT FROM AUTHOR]