title: Lanthanum-nickel alloy
text: # Lanthanum-nickel alloy
  
  Lanthanum forms several alloys with nickel, including $LaNi_5,$ $La_2Ni_7,$ $LaNi_2,$ $LaNi_3,$ $La_2Ni_3,$ LaNi and $La_3Ni$ etc.
  
  ## $LaNi_5$
  
  $LaNi_5$ is an intermetallic compound with a $CaCu_5$ structure. It belongs to the hexagonal crystal system. It can be oxidized by air above 200 °C, and react with hydrochloric acid, sulfuric acid or nitric acid above 20 °C. $LaNi_5$ can be used as a catalyst for hydrogenation reactions.
  
  ## Other alloys
  
  In addition to $LaNi_5,$ there are other alloys such as $La_2Ni_7,$ $LaNi_2,$ $LaNi_3,$ $La_2Ni_3,$ LaNi, and $La_3Ni,$ and nonstoichiometric alloys such as $LaNi_{2.286}$ (tetragonal, space group I4̄2m). The nickel atoms in $La_xNi_y$ can also be replaced by other atoms, such as $LaNi_{2.5}Co_{2.5}.$
  
  