(Sr 3 N x ) E and (Ba 3 N x ) E ( E = Sn, Pb): Preparation, Crystal Structures, Physical Properties and Electronic Structures

Black powders of (Sr 3 N x )Sn ( x = 0.74(2), a = 523.51(5) pm), (Ba 3 N x )Sn ( x = 0.62(2), a = 552.93(1) pm), (Sr 3 N x )Pb ( x = 0.81(3), a = 524.22(1) pm) and (Ba 3 N x )Pb ( x = 0.826(4), a = 554.40(3) pm, Pm 3¯ m , No. 221, Z = 1) were obtained from reactions of melt beads of the respective metals with bulk compositions of A 3 E ( 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 (Ba 3 N x )Sn ( x = 0.64(1); neutron diffraction: R Bragg = 8.70 %, R F = 6.10 %; X‐ray diffraction: R Bragg = 11.60 %, R F = 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 ( A 3 N 2/3 ) E reveal the phases as intrinsic metals and suggest the tendency towards higher nitrogen site occupation ( x > ⅔).