Single crystals of (Ca/Eu)MgSi and (Ca/Eu)5Mg19Si12 were produced by using metal flux synthesis in magnesium and aluminum mixtures at either a 1:1 or 2:1 Mg/Al ratio. The (Ca/Eu)Mg/Si phases exhibit the orthorhombic TiNiSi structure type (space group Pnma); the (Ca/Eu)5Mg19Si12 compounds have the hexagonal Ho5Ni19P12 type (space group P-62m). As the reactant ratios of calcium and europium are varied, the products range from CaMgSi on one end to Eu5Mg19Si12 on the other, with the shift from the orthorhombic (Ca/Eu)MgSi to the hexagonal (Ca/Eu)5Mg19Si12 occurring with europium-rich reactions. Preliminary magnetic susceptibility data for these compounds show paramagnetic behavior at higher temperatures indicative of divalent europium; they order antiferromagnetically below 8 K. Similar investigations are being carried out with calcium replaced by strontium and barium.

Metal flux synthesis and effects of Eu/Ca ratio on structure type and magnetism of Ca/Eu/Mg/Si Zintl phases

2019 Spring National Meeting

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