Sr[BeSi2N4]:Eu2+/Ce3+ and Eu[BeSi2N4]: Nontypical Luminescence in Highly Condensed Nitridoberyllosilicates.

M[BeSi2N4] (M=Sr,Eu), crystallizing in the hexagonal space group P 2c, was synthesized from Sr(NH2)2, Be3N2, and “Si(NH)2” in W crucibles under a N2 atmosphere in a radio‐frequency furnace. The crystal structure was solved from powder X‐ray diffraction data by the charge‐flipping method (Sr[BeSi2N4]: a=4.86082(2), c=9.42264(4) Å, Z=2; Eu[BeSi2N4]: a=4.85848(1), c=9.41615(4) Å). M[BeSi2N4] contains a highly condensed rigid network of trigonal planar [BeN3] units that are connected to Si2N7 double tetrahedra by common vertices. M[BeSi2N4] (M=Sr,Eu) are the first examples of nitridoberyllosilicates and are isotypic to the oxoberyllate Sr[Be3O4]. Eu2+‐doped Sr[BeSi2N4] and Eu[BeSi2N4] show orange‐trapped exciton emission (λem=605 nm, fwhm ≈126 nm), whereas Ce3+‐doped samples of Sr[BeSi2N4] show nontypical yellowish‐orange luminescence. Sr[BeSi2N4] has a large band gap of ≈4.4 eV and shows high chemical and thermal stability. Eu2+‐doped beryllates with regular 4f65d1→4f7‐emission could be interesting for future application in LEDs upon doping with Eu2+ or Ce3+ due to large band gaps, rigid networks, and chemical and thermal stability. [ABSTRACT FROM AUTHOR]