CAMG2N2 - A MIXED ALKALINE-EARTH METAL NITRIDE WITH ANTI-LA2O3 STRUCTURE

CaMg2N2 (trigonal, P (3) over bar m1 (Nr. 164); a = 354.046(1), c = 609.079(2) pm; Z = 1) is isotypic to the anti-La2O3 structure with octahedral and tetrahedral coordination for Ca-2 divided by and Mg2+ ions, respectively. The compound has been prepared by the reaction of the binary nitrides Ca3N2 and Mg3N2 (molar ratio 1:2) in a tungsten crucible under a pure nitrogen atmosphere at 1050 degrees C. The formation of the solid CaMg2N2 may be interpreted in analogy to reactions of related oxides as an acid-base reaction between the binary nitrides with different coordination tendencies of Ca2+ and Mg2+ ions. An analysis of the binary aristotype anti-La2O3 indicates that this structure is predisposed for building ternary phases.