Synthesis and Structure of Ba[ZrN₂] and Ba₂[NbN₃]

Abstract

Ba3N2 reacts at 950°C under pure N2 with Zr to yield dark red, air‐sensitive Ba[ZrN2]. This new compound crystallizes in the tetragonal space group P4/nmm with a = 416.10(2), c = 839.2(1) pm and Z = 2. The crystal structure was solved and refined using X‐ray and neutron powder diffraction data. In the nitrido zirconate [ZrN2]2− the Zr atoms exhibit a square‐pyramidal coordination by five N atoms at distances of 201(3) and 220.2(2) pm. The pyramids share all the edges in the basal plane to form layers parallel to (001) with their apices alternately pointing up and down. The Ba2+ cations are integrated into these layers at the levels of the pyramidal apices. The structure can be interpreted as a stuffed PbFCl type. Ba2[NbN3] is formed by the reaction of Ba3N2 and NbN or of Ba and Nb at 1 000°C under N2. Isostructural to Ba2[TaN3] it crystallizes in the monoclinic space group C2/c with a = 613.2(3), b = 1 176.8(3), c = 1 322.9(4) pm, β = 91.65(2)°, Z = 8. The nitrido niobate anions form chains of corner sharing NbN4 tetrahedra with distances NbN between 188(1) and 199.9(9) pm.

Synthesis, Structure, and Magnetic Properties of the New Ternary Nitride BaHfN2and of the BaHf1−xZrxN2Solid Solution

“…Data collected over much shorter times, although showing less evidence of reaction with air, proved to be of too low a quality for accurate refinement, and best results were obtained by doubling the thickness of Mylar film (0.2 mm) in the windows of the aluminum PXD holders and collecting data over longer times. A full-profile Rietveld refinement (30) of BaHfN was performed using the Phillips PC RIETVELD PLUS (31, 32) package for 6251 profile points with the BaZrN structure (20) as an initial model and with cell parameters obtained from least-squares fitting of PXD data. Peak shapes were modeled using the pseudo-Voigt function and the background was refined as a polynomial function.…”

“…9.6 K. Magnetic measurements conducted on SrZrN and SrHfN suggest these materials are intrinsically diamagnetic at room temperature (21). BaZrN , however, shows anomalous magnetic behavior for a material of presumed s"0 electronic configuration, exhibiting temperature-independent paramagnetism between 20 and 300 K (20).…”

“…BaCeN possesses a layered structure and is isostructural with -RbScO (19). BaZrN is isotypic with KCoO , which contains layers made up of edge-sharing Zr-N square-base pyramids (20). The nitrides SrZrN , SrHfN (21), and CaTaN (22) all form structures isotypic with -NaFeO .…”

Structural Classification of Quasi-One-Dimensional Ternary Nitrides

“…Table 2. Selected structural properties of A2MN3 (A = Sr, Ba; M = V, Nb, Ta) and Ca2VN3 [57][58][59].…”

“…These chains run parallel to [100]. The Ba 2+ , Sr 2+ , and Ca 2+ cations lie on two crystallographically independent sites, both seven coordinate, A(1) is in distorted pentagonal bipyramidal coordination and A(2) shows monocapped trigonal prismatic coordination [59]. [57][58][59].…”