Crystal growth of incommensurate members of 2H-hexagonal perovskite related oxides: Ba4M Pt3−O9 (M=Co, Ni, Cu, Zn, Mg, Pt)

A Family of A-Site Cation-Deficient Double-Perovskite-Related Iridates: Ln9Sr2Ir4O24 (Ln = La, Pr, Nd, Sm)

The compositions of the general formula Ln_{11- x}Sr _xIr₄O₂₄ (Ln = La, Pr, Nd, Sm; 1.37 ≥ x ≥ 2) belonging to a family of A-site cation-deficient double-perovskite-related oxide iridates were grown as highly faceted single crystals from a molten strontium chloride flux. Their structures were determined by single-crystal X-ray diffraction. On the basis of the single-crystal results, additional compositions, Ln₉Sr₂Ir₄O₂₄ (Ln = La, Pr, Nd, Sm), were prepared as polycrystalline powders via solid-state reactions and structurally characterized by Rietveld refinement. The compositions Ln₉Sr₂Ir₄O₂₄ (Ln = La, Pr, Nd, Sm) contain Ir(V) and Ir(IV) in a 1:3 ratio with an average iridium oxidation state of 4.25. The single-crystal compositions La_9.15Sr_1.85Ir₄O₂₄ and Pr_9.63Sr_1.37Ir₄O₂₄ contain relatively less Ir(V), with the average iridium oxidation states being 4.21 and 4.09, respectively. The magnetic properties of Ln₉Sr₂Ir₄O₂₄ (Ln = La, Pr, Nd, Sm) were measured, and complex magnetic behavior was observed in all cases at temperatures below 30 K.