Layered Nitridomagnesogallates CaMg2GaN3 and CaMg2Ga2N4. Issue 7 (20th February 2017) - Poesl, Christine
Abstract : The quaternary nitrides CaMg2 GaN3 and CaMg2 Ga2 N4 were synthesized by means of solid‐state metathesis reactions. The crystal structures of both nitridomagnesogallates contain layers made up of either tetrahedral M N4 units (CaMg2 Ga2 N4 ) or both tetrahedral M N4 units and planar M N3 triangles (CaMg2 GaN3 ) with mixed occupation of central atoms Mg and Ga. CaMg2 GaN3 was obtained as a gray powder. Its crystal structure was determined on the basis of X‐ray powder diffraction data [ P 63 / mmc (no. 194), a = 3.43093(8), c = 17.3989(5) Å, V = 177.368(9) Å 3, Z = 2]. The compound is isotypic with CaMg2 AlN3 and homeotypic with Ca2 Mg5 GeN6, ScAl3 C3, and UAl3 C3 . The crystal structure of CaMg2 Ga2 N4 [ P 3 m 1(no. 164), a = 3.3859(3), c = 11.2378(11) Å, V = 111.57(2) Å 3, Z = 1] was determined from single‐crystal X‐ray diffraction data and corroborated by Rietveld refinement. TEM investigations confirmed the metrics of both crystal structures and indicate the presence of both compounds as side products within one reaction batch. Structural similarities between CaMg2 GaN3 and CaMg2 Ga2 N4 are discussed. Abstract : CaMg2 GaN3 and CaMg2 Ga2 N4 represent two novel nitridogallates with layered crystal structures. Syntheses were performed by employing solid‐state metathesis reactions, which is a new synthetic approach for nitridogallates. Owing to the strong structural relationship between both compounds, formation of composite crystals also seems likely.