Nitrides with Inverse K2[NiF4] Structure: (R1–xCa3+xN1–x/3)Bi2 with R = Rare‐Earth Metal

The novel nitrides (R_1–xCa_3+xN_1–x/3)Bi₂ (with R = La, Ce, Pr) crystallize in the K₂NiF₄] structure type (I4/mmm, No. 139, Z = 2). Samples (La_1–xCa_3+xN_1–x/3)Bi₂ with x = 0.10, 0.05, 0.00, (Ce_1–xCa_3+xN_1–x/3)Bi₂ with x = 0.30, and (PrCa₃N)Bi₂ were obtained as single phase microcrystalline powders according to X‐ray diffraction and the crystal structure details were derived from Rietveld refinements based on X‐ray and neutron diffraction powder patterns. A partial order of R³⁺/Ca²⁺ on two crystallographic sites is governed by different ionic radii and charges. (La_1–xCa_3+xN_1–x/3)Bi₂ and (Ce_1–xCa_3+xN_1–x/3)Bi₂ exhibit small homogeneity ranges and typically a nitrogen deficiency. In contrast, for (PrCa₃N)Bi₂ no indications for a significant homogeneity range or deficiency of nitrogen was observed. (La_1–xCa_3+xN_1–x/3)Bi₂ with x = 0.05 is a diamagnet. X‐ray absorption spectroscopy at the CeL₃‐edge as well as magnetic susceptibility measurements evidence that (Ce_1–xCa_3+xN_1–x/3)Bi₂ with x = 0.30 contains Ce³⁺ in the 4f¹ configuration. According to electrical resistivity data, samples from all three systems are heavily doped semiconductors.