Four new metal silicides were grown as competing products from reactions of silicon, barium and ytterbium in Mg/Al flux; the dominant product is determined by heating profile as well as by reactant ratio. The compounds Ba2Yb0.88Mg11.12Si7, Ba5Yb2.26Mg16.73Si12, Ba6Yb1.84Mg18.16Si13 and Ba20Yb4.7Mg61.3Si43 all exhibit hexagonal crystal structures that are analogous to ternary metal phosphides (Zr2Ni12P7, Ho5Ni19P12, Zr6Ni20P13 and Ho20Ni66P43, respectively). The structures feature building blocks comprised of silicon anions surrounded by nine metal cations; these tricapped trigonal prismatic Si@(Mg/Yb/Ba)9 polyhedra share faces to form the overall structures. In-situ neutron diffraction data collected on a reaction mixture as it was heated and cooled allowed for observation of the crystallization of Ba20Yb4.7Mg61.3Si43 from the melt at 630°C.

Metal flux growth of new multinary metal silicide zintl phases

2019 Spring National Meeting

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