Geometrically frustrated double perovskite synthesis and structural characterization

Geometric frustration occurs when magnetic order is inhibited by the arrangement of ions in a material. Typically associated with triangular or tetrahedral coordination of moments favoring antiparallel alignment, frustration results in rich magnetic phase diagrams, and is thus of interest for elucidating the development of magnetism in materials.~Double perovskites A$_{2}$BB'O$_{6}$ potentially exhibit frustration, and the chemical versatility of the perovskite structure enables systematic studies of frustration physics across a wide array of compounds. We report structural characterization of compounds based on the 4d$^{1}$ Mo$^{5+}$ ion synthesized via solid state methods. We find that Ba$_{2}$YbMoO$_{6}$ and Ba$_{2}$LuMoO$_{6}$ crystallize in a simple cubic perovskite structure, whereas Sr$_{2}$YMoO$_{6\, }$exhibits a monoclinic structure, consistent with prior results. Syntheses of Sr$_{2}$GaMoO$_{6}$, Ca$_{2}$AlMoO$_{6}$, Sr$_{2}$ScMoO$_{6}$, Ba$_{2}$InMoO$_{6}$, Sr$_{2}$AlMoO$_{6}$, Ba$_{2}$ScMoO$_{6}$, Ba$_{2}$GaMoO$_{6}$, and Ba$_{2}$AlMoO$_{6}$ were attempted, although the desired phases were not produced. Possible causes include loss or non-reactivity of precursors, and phase diagrams favoring non-perovskite structures.