(Sr₃N_x)E and (Ba₃N_x)E (E = Sn, Pb): Preparation, Crystal Structures, Physical Properties and Electronic Structures

Abstract

Black powders of (Sr3Nx)Sn (x = 0.74(2), a = 523.51(5) pm), (Ba3Nx)Sn (x = 0.62(2), a = 552.93(1) pm), (Sr3Nx)Pb (x = 0.81(3), a = 524.22(1) pm) and (Ba3Nx)Pb (x = 0.826(4), a = 554.40(3) pm, Pm3¯m, No. 221, Z = 1) were obtained from reactions of melt beads of the respective metals with bulk compositions of A3E (A = Sr, Ba; E = Sn, Pb) in nitrogen atmosphere at temperatures in the range of 970 K ‐ 1220 K. The compositions were derived from chemical analyses, supported by Rietveld refinements based on powder X‐ray and neutron diffraction patterns taken on (Ba3Nx)Sn (x = 0.64(1); neutron diffraction: RBragg = 8.70 %, RF = 6.10 %; X‐ray diffraction: RBragg = 11.60 %, RF = 12.00 %). The phases crystallize in cubic anti‐perovskite type arrangements. Measurements of the magnetic susceptibility indicate a nearly temperature independent paramagnetism. The electrical resistivities are weakly temperature dependent with resistivities at 300 K in the order of 1 mΩ·cm. Electronic structure calculations on ordered superstructures of the composition (A3N2/3)E reveal the phases as intrinsic metals and suggest the tendency towards higher nitrogen site occupation (x > ⅔).

Inverse Perovskites (RE3N)Sn with RE = La, Ce, Pr, Nd, Sm: Preparation, Crystal Structures and Physical Properties

“…Previously reported were the inverse cubic perovskites (Ca 3 N)Sn [14], (Sr 3 N 1−x )Sn, (Ba 3 N 1−x )Sn [15], (Nd 3 N)Sn [16], (Cr 3 N)Sn [17], (Mn 3 N)Sn [17], (Mn 3 N)Mn 0.5 Sn 0.5 [18], and (Fe 3 N)Fe 0.4 Sn 0.6 [19], the filled Mn 5 Si 3 type (Zr 3 N)Zr 2 Sn 3 [20] and the filled Cr 5 B 3 type (La 4 N)LaPb 3 [21]. Recently, the first nitridostannate(II) Na[SnN] was reported [22].…”

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

“…The corresponding group 14 compounds are discussed in terms of electron deficient metals of the composition (Ca 3 N)E [E(14) = Ge, Sn, Pb], [18] however, more recent investigations reveal a nitrogen deficiency for the Sr and Ba compounds moderating the electronic balance. [20] Electron excess main-group element phases of E(16) = Se, Te could not be obtained. [18] The nitride chemistry of the anti-Perovskite type compounds under consideration connects to the closely related oxides, where similar compounds are known with alkalineearth and alkali metal constituents, e.g.…”

“…[17] The electrical resistivities of the strontium and barium compounds were also studied on pressed powder pellets, but in a larger temperature range below ambient. [20] Generally, the samples display only slightly temperature dependent metallic temperature characteristics with low resistivities in the order of 0.1-1 mΩ·cm. Similar behavior is known from ternary inter-transition metal nitrides as, e.g., FeWN 2 and MnMoN 2 .…”

“…[68,69] Originally the cubic calcium Perovskites with E = Ge, Sn, Pb were reported with the composition (Ca 3 N)E, [18] later the systems Sr,Ba-Sn,Pb-N were exemplarily studied in deeper detail indicating the formation of further cubic Perovskites but with a nitrogen deficiency according to (A 3 N x )E. [20,70] DTA/ TG measurements on melt beads with the general composition "A 3 E" in nitrogen atmosphere already indicated the uptake of less than one equivalent nitrogen per "A 3 Sn,Pb" composition. The weight gain typically corresponds to an uptake of about 2 / 3 equivalents nitrogen per formula unit "A 3 E".…”

“…[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.…”