The electronic and electrochemical properties of the LaNi5, LaNi4Al and LaNi3AlCo systems

Nanocrystalline LaNi5-type materials have been prepared by mechanical alloying (MA) followed by annealing. The amorphous phase forms directly from the starting mixture of elements, without formation of other phases. The LaNi5, LaNi4Al and LaNi3AlCo systems crystallize in the hexagonal CaCu5 type structure (P6/mmm). The electrochemical properties of these type of materials, in which there has been a partial substitution of Ni by Al and Al–Co, have been investigated and discharge capacity enhancement has been observed. The electronic structure has been studied by the tight binding version of the linear muffin-tin orbital method in the atomic sphere approximation (TB-LMTO ASA). Total energy calculations showed that the Al and Co impurities prefer 3g positions.