Synthesis and Characterization of BaLiRu 5 O 11 , BaCu 1+ x Ru 5– x O 11 , and BaLi 1– x Cu x + δ Ru 5– δ O 11 : Crystal Structures and Valence States

Single crystals of the quaternary R ‐type ferrites BaLiRu 5 O 11 [ a = 11.628(6) Å, c = 13.7596(5) Å], and BaCu 1+ x Ru 5– x O 11 [ a = 11.6825(6) Å, c = 13.8051(7) Å], and their quinary solid solution BaLi 1– x Cu x + δ Ru 5– δ O 11 [ a = 11.6453(2) Å, c = 13.7772(3) Å] were obtained by flux growth technique. X‐ray diffraction reveals the compounds to crystallize in space group P 6 3 / m with Z = 8. Measurements of the magnetic susceptibility of BaLiRu 5 O 11 and BaCu 1+ x Ru 5– x O 11 , applying Curie–Weiss fits, confirm their paramagnetic behavior with temperature independent contributions of χ 0,mol = 3.27 × 10 –3 cm 3 · mol –1 and χ 0,mol = 2.47 × 10 –3 cm 3 · mol –1 , respectively. Furthermore, the valence state of Ru in BaLiRu 5 O 11 and BaCu 1+ x Ru 5– x O 11 was determined to +3.8 by X‐ray absorption spectroscopy. Cu in BaCu 1+ x Ru 5– x O 11 is dominating in a +2 state according to X‐ray photoelectron and X‐ray absorption spectroscopy, while a minor amount in +1 state may represent the excess copper substituting some Ru within a distorted Kagome net arrangement.