(Sr₃N)E and (Ba₃N)E (E = Sb, Bi): Synthesis, Crystal Structures, and Physical Properties

Abstract

Single phase powders of (Sr3N)Sb, (Sr3N)Bi ($Pm{\bar 3}m$, No. 221, Z = 1, Sb: a = 517.25(2) pm, V = 138.390(8) · 106 pm3, Bi: a = 520.691(8) pm, V = 141.170(4) · 106 pm3), (Ba3N)Sb, and (Ba3N)Bi (P63/mmc, No. 194, Z = 2, Sb: a = 753.33(3) pm, c = 664.45(3) pm, V = 326.56(2) · 106 pm3, Bi: a = 761.28(4) pm, c = 668.05(3) pm, V = 335.30(2) · 106 pm3) were obtained from reactions of melt beads of the respective elements with bulk compositions of A3E (A = Sr, Ba; E = Sb, Bi) in nitrogen atmosphere of ambient pressure at T = 1070 K (Sr) and T = 1120 K (Ba). The compositions were derived from chemical analyses and supported by Rietveld refinements based on powder X‐ray diffraction patterns. The Sr containing compounds crystallize in the cubic anti‐perovskite type arrangement, the Ba containing compounds in the hexagonal anti‐BaNiO3 structure type. Magnetic susceptibility and electrical resistivity data indicate that the compounds are diamagnetic semiconductors. The optical band gaps of (Sr3N)Sb and (Sr3N)Bi were determined by diffuse reflectivity to 1.15 eV and 0.89 eV, respectively. The experimental results are in agreement with electronic structure calculations. Chemical bonding is characterized in a simplified picture as ionic with significant orbital mixing.

Synthesis, Characterization, and Chemical Bonding Analysis of the Lithium Alkaline‐earth Metal Gallide Nitrides Li2(Ca3N)2[Ga4] and Li2(Sr3N)2[Ga4]

“…[23] The distances between the alkaline-earth metal and nitrogen of 249.33(2) pm for the calcium and 262.70(2) pm for the strontium compound are slightly longer than those in the vertex-sharing (NAE 6 ) octahedra in (Ca 3 N)Sb [39] and (Sr 3 N)Sb [40] [242.7 pm and 258.63(1) pm], respectively, and for strontium closer to the distance in the isolated (NSr 6 ) octahedra of (Sr 6 N)[Ga 5 ] (260.2 pm).…”

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

“…[17][18][19][20][21]23,[50][51][52] Temperatures applied range from 700°C to 1300°C depending on the element combination with dwelling times as short as 10 h to well above 2 d. A widespread of reaction vessels has been found appropriate, starting with open alumina and transition metal crucibles for reactions in nitrogen atmosphere and extending to sealed fused silica tubes and metal capsules. Sealed vessels can be used if sufficient or especially the exact desired amount of nitrogen for compound formation is already contained within the starting materials, for example via use of binary alkaline-earth metal nitrides.…”

“…[75][76][77] [24,27,28] Cubic (anti)Perovskite nitrides with group 15 elements have been reported for the systems (Mg 3 N)E with E = As, Sb, [19] (Ca 3 N)E with E = P, As, Sb, Bi, [18] and (Sr 3 N)E with E = Sb, Bi. [21,70] Table 1 gathers selected interatomic distances. For (Ca 3 N)P and (Ca 3 N)As distortions from cubic to the orthorhombic GdFeO 3 structure type were observed at ambient conditions (space group Pnma).…”

“…Structure representations of cubic Perovskite compounds (top) and (Ba 3 N)E (E = Sb, Bi) crystallizing in a hexagonal BaNiO 3 structure (bottom). [21] Crystallographic unit cells are indicated. Light gray spheres: A, medium gray spheres: E and dark gray spheres: N. Octahedra A 6 N are shown as well as coordination polyhedra of E by A. metallic properties.…”

“…[17,18] Additionally, it was shown, that Ca can be replaced by Mg for E = As, Sb. [19] Furthermore, the formation of respective compounds with A = Sr, Ba is feasible in combination with at least E = Sn, Pb, Sb, Bi, [20,21] and the list of compounds can be expanded to group 13 element compounds, i.e., E = In, Tl. [22,23] All phases (Ca 3 N)E crystallize in the cubic Perovskite structure type represented in Figure 1 (for E = P, As at ambient conditions distorted to an orthorhombic crystal structure) and exhibit interesting features concerning the electronic situation: Assuming calcium and nitrogen to form ions Ca 2+ and N 3-, respectively, one can achieve -within the same structure type -various electronic situations: from an electron excess present in the transition metal compound (Ca 3 N)Au [formally (Ca 2+ ) 3 (N 3-)(Au -)·2e -], [17] via compounds (Ca 3 N)E [E(15) = P 3-, As 3-, Sb 3-, Bi 3-], [18] which obey the octet rule, to an electron deficiency as in (Ca 3 N)Tl.…”