Stacking Design of Inverse Perovskites:  The Systems (Sr_3-xBa_xN)E, E = Bi, Sb

Abstract

The first representatives of 4H (BaMnO3-type structure, P63/mmc, Z = 4) and 9R (BaMnO3-type structure, Rm, Z = 9) inverse Perovskite phases are presented. The phases are obtained within the solid solutions (Sr3-xBaxN)E with E = Bi, Sb. The crystal structures and homogeneity ranges were studied by combined X-ray and neutron diffraction as well as chemical analyses. The cubic Perovskite phase with Bi (Sb) is stable in the range of 0.00 < or = x < or = 0.90(5) (0.00 < or = x < or = 1.30(5)), the 4H variant is stable for 1.55(5) < or = x < or = 2.10(5) (1.85(5) < or = x < or = 2.45(5)), the 9R structure is stable for 2.50(2) < or = x < or = 2.55(2) (2.56(2) < or = x < or = 2.60(2)), and the 2H phase is stable for 2.75(5) < or = x < or = 3.00 (2.80(5) < or = x < or = 3.00). Ba occupies preferable sites in the hexagonal stacking of close packed layers of alkaline earth metal ions and E3-; Sr is mainly located in cubic stacked layers. The phase order upon going from cubic (Sr3N)E to 2H-type (Ba3N)E concomitant to the pronounced Sr/Ba partial order can, in general, be rationalized considering the Coulomb repulsion of nitride ions, as well as the size and charge density of the alkaline earth metal ions.

Alkaline‐earth Metal Nitrides of the Main‐Group Elements: Crystal Structures and Properties of Inverse Perovskites

“…[89] The quaternary system (Sr 3-x Ba x N)Bi reveals a composition range around x = 1.5 (approximate range 1.3 Յ x Յ 2.0, depending on temperature), in which a BaMnO 3 type crystal structure with a 4H stacking sequence is formed. Additionally, with a higher barium content of x ≈ 2.3 a 9R arrangement with a BaRuO 3 type crystal structure was observed.…”

“…Representations of the phases (Sr 3-x Ba x N)E with 4H BaMnO 3 type crystal structure (x ≈ 1.5, top) and 9R BaRuO 3 type structure (x ≈ 2.3, bottom). [89] Dark gray spheres: N, medium gray spheres: E, light gray spheres: Ba, Sr. Sr is mainly located at vertexsharing sites of (A 6 N) octahedra, Ba at face-sharing positions. The unit cells are indicated.…”

“…Octahedra A 6 N are shown as well as coordination polyhedra of E by A. Normalized volume data for stacking variants in the system (Sr 3-x Ba x N)Bi. [89] The occurring interconnections of octahedra in the structures are depicted. homogeneity range.…”

“…[89] A 3n+1 ON n-1 Figure 5 shows a section of the crystal structure of ((Ba 0.78(1) Sr 0.22 ) 4 O)Bi 2 , which is an isotype of a multitude of ternary compounds (A 4 O)E 2 with E = P, As, Sb, Bi; A = Ca, Sr, Ba, Eu, and Yb in the oxidation state +2. [91][92][93][94][95][96][97][98][99] Oxygen centered octahedra of alkaline-earth metal ions share vertices to form layers (A 2 A 4/2 O), which are separated by Bi 3-anions.…”

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

“…Particularly, the alkaline-earth metal nitrides of group 15 elements E = P, As, Sb, Bi with the composition (A 3 N)E show diamagnetism and electrically insulating properties [15][16][17]. The crystal structures cover the range of cubic Perovskites for, e.g., (A 3 N)E with A = Ca, Sr and E = Sb, Bi, orthorhombic distortion variants in space group Pnma for (Ca 3 N)E with E = P, As [16,17], 2H hexagonal Perovskites for (Ba 3 N)Sb and (Ba 3 N)Bi [15] and 4H as well as 9R stacking variants for the quaternary substitution series (Sr 3-x Ba x N)Sb and (Sr 3-x Ba x N)Bi [18].…”