The Crystal Structure of Nitridomagnesogermanate Ba[Mg 3 GeN 4 ]:Eu 2+ and Theoretical Calculations of Its Electronic Properties

Nitridomagnesogermanate Ba[Mg 3 GeN 4 ]:Eu 2+ was synthesized by the NaN 3 route in weld‐shut tantalum ampules by reaction of the elements in molten sodium with NaN 3 as nitrogen source at 780 °C. The crystal structure was solved and refined on the basis of single‐crystal X‐ray diffraction data. Ba[Mg 3 GeN 4 ]:Eu 2+ crystallizes in the UCr 4 C 4 structure type [space group I 4/ m (no. 87), a = 8.3921(12), c = 3.4813(7) Å, Z = 2] and exhibits a highly condensed anionic network made up of statistically disordered (Mg/Ge)N 4 tetrahedra, which are connected to each other by common vertices and edges to form vierer ring channels along [001]. Ba 2+ is located in every second channel and has cubelike coordination by eight N atoms. Theoretical calculations of the electronic properties of Ba[Mg 3 GeN 4 ]:Eu 2+ are discussed to understand the absence of photoluminescence in the visible range and for comparison with other luminescent materials that are structurally related to Ba[Mg 3 GeN 4 ]:Eu 2+ .