About Binary and Ternary Alkaline Earth Metal Nitrides

Abstract

Binary and ternary alkaline earth metal nitrides compounds have been synthesized and characterized by the means of X-ray structure analysis. By the reaction of the alkaline earth metals Be, Mg, and Ca with dry nitrogen, we obtained crystalline material of Be3N2 (1), Mg3N2 (2), and Ca3N2 (3), respectively. For these three compounds we could confirm the cubic anti bixbyite structure (Ia3 (#206); 1: a = 814.92(1) pm; 2: 997.26(6) pm and 3: a = 1147.86(2) pm). By reacting 1 : 2 : 1 mixtures of Ae (Ae = Ca, Sr) : Mg : NaN3 we synthesized the ternary nitrides CaMg2N2 (4) and SrMg2N2 (5). We confirmed the structural data obtained by Rietveld-analysis of X-ray powder diffraction data for 4 and found 5 to be isotypic (anti-C–M2O3 structure, trigonal, P 3ml (#164); 4: a = 354.77(5) pm, c = 609.60(12) pm; 4: a = 362.20(5), c = 635.90(13) pm). The indexing of the powder diffractogram of “Ca3Mg3N4” and refining the lattice parameters (hexagonal, a = 352.9(2) and c = 607.5(5) pm) suggest its identity with 4. The black “low-temperature phase of Ca3N2” has been synthesized and and the X-ray powder diffractogram has been recorded. The reactions of this phase are also described. The yellow “high-temperature phase of Ca3N2” was found to be Ca4N2(CN2).