posted on 2021-08-17, 17:07authored byAshini
S. Jayasinghe, You Lai, Wesley M. Potter, Cory J. Windorff, Ryan Baumbach, Thomas E. Albrecht-Schönzart, Susan E. Latturner
An1.33T4Al8Si2 (An
= Ce, Th, U, Np; T = Ni, Co) were synthesized in metal flux reactions
carried out in aluminum/gallium melts. In previous work, U1.33T4Al8Si2 (T = Co, Ni) analogues
were formed by arc-melting U:T:Si and reacting this mixture in Al/Ga
flux. However, in the current work, all compounds were synthesized
by using AnO2 reactants, taking advantage of the ability
of the aluminum in the flux to act as both solvent and reducing agent.
While reactions with T = Co yielded hexagonal Gd1.33Fe4Si10-type quaternary phases for all An, reactions
with T = Ni produced these compounds only with An = U and Np. For
reactions with An = Ce and Th, the reactions led instead to the formation
of AnNi3–xSixAl4–yGay phases, with the tetragonal KCu3S4 structure
type. Attempts to synthesize plutonium analogues Pu1.33T4Al8Si2 were also unsuccessful,
producing the previously reported PuCoGa5 and Pu2Ni5Si6 instead. Magnetic data collected on
the neptunium analogues Np1.33T4Al8Si2 (T = Ni, Co) show antiferromagnetic coupling at low
temperatures and indicate a tetravalent state for the Np ions.