The Inverse Perovskite Nitrides (Sr₃N_2/3–x)Sn, (Sr₃N_2/3–x)Pb, and (Sr₃N)Sb: Flux Crystal Growth, Crystal Structures, and Physical Properties

Abstract

Black single crystals with metallic luster of (Sr3N2/3–x)E (E = Sn, Pb) and (Sr3N)Sb were grown in lithium flux from strontium nitride, Sr2N, and tin, lead, or antimony, respectively. Nitrogen deficiency in the tin and the lead compound is a result of the higher ionic charge of the tetrelide ions E4– as compared to the antimonide ion Sb3–. In contrast to microcrystalline samples from solid state sinter reactions obtained earlier, the flux synthesis induces nitrogen order in the nitrogen deficient tetrelides. The antimony compound crystallizes as inverse cubic perovskite [a = 517.22(5) pm, Z = 1, space group Pm3m, no. 221] with fully occupied nitrogen site, whereas the nitrogen deficient tin and lead compounds exhibit partially ordered arrangements and a certain phase width in respect to nitrogen contents. For the tetrelides, the nitrogen order leads to a cubic 2 × 2 × 2 superstructure [E = Sn: a = 1045.64(8) pm for x = 0, a = 1047.08(7) pm for x = 0.08; and E = Pb: a = 1050.7(1) pm for x = 0, space group Fm3m, no. 225] as derived from single‐crystal X‐ray diffraction data. The metallic tetrelides show diamagnetic behavior, which is consistent with electronic structure calculations.

Li16Sr6Ge6N, Li16Sr6Ge6.5 and related lithium alkaline‐earth metal tetrelides: Alternative filling of voids by nitride or tetrelide ions

“…In metalide nitrides and metalide nitridometalates, the complex anionic substructures are separated by the cations. Isolated metalide ions are observed in the inverse perovskite (Sr 3 N 0.67 )[Ge], [8][9] and Sr 17 [Ge] 2 [GeN 3 ] 2 [GeN 4 ] 2 , [3] and infinite zigzag chains in e. g. Sr 6 [Ge 4 ][GeN 2 ]. [6] Isolated (non-covalent bonded) nitride ions in metalide nitrides are typically located in octahedra formed by alkaline-earth metal ions.…”

Perovskite Distortion Inverted: Crystal Structures of (A3N)As (A = Mg, Ca, Sr, Ba)

“…Compared to these materials with perovskite structure, only relatively little is known about inverse perovskites, where the ionic charges and thus the polarizabilities of the atomic constituents are inverted . Considering alkaline earth metal nitrides, (Mg 3 N)As and the heavier homologues of the title compounds, namely ( A 3 N)Sb ( A = Mg, Ca, Sr, Ba), and ( A 3 N)Bi ( A = Ca, Sr, Ba),, are examples for undistorted cubic inverse perovskites for the Mg, Ca, and Sr containing compounds and hexagonal inverse perovskites for the Ba compounds. These compounds were shown to represent semiconductors, putting forward a simple ionic description ( A 2+ ) 3 (N 3– ) E 3– .…”

“…These compounds were shown to represent semiconductors, putting forward a simple ionic description ( A 2+ ) 3 (N 3– ) E 3– . Upon going to the group 14 elements tin and lead, the charge balance in the respective compounds is retained by only partial occupation of the nitrogen positions, leading to compounds with approximate compositions ( A 3 N 2/3 ) E (14) [ A = Sr, Ba; E (14) = Sn, Pb],, whereas in combination with the trielide Tl the situation changes back to a fully occupied nitrogen site in the metallic cubic perovskite (Ca 3 N)Tl …”