Structure and Photoluminescence Properties of EuSiN₂

With the europium nitridosilicate, EuSiN₂ a novel member of the multifaceted MSiN₂ family is presented and compared with the structural similar compounds MSiN₂ (M = Ca, Sr, Ba). A different way of presenting the structure as M-N polyhedra layers is introduced. The crystal structure of EuSiN₂, being isotypical to SrSiN₂, was determined and refined based on powder X-ray diffraction data in space group P2₁/c (no. 14) with a = 5.96381(2) Å, b  = 7.25982(3) Å, c  = 5.488338(19) Å, β = 113.33°, V  = 218.18(5) ų, and Z  = 4. As the Eu²⁺-doped MSiN₂ compounds show excellent luminescence properties as LED phosphors, the luminescence behaviour of dark red emitting EuSiN₂ has been investigated as well. Two emission peaks are visible at 708 nm and 764 nm. Many europium-doped nitridosilicates show more or less developed shoulders for their luminescence peaks, but two clearly shaped emission peaks are a novel feature for nitridosilicates. Comprehensive and detailed comparisons are given and discussed based on works in literature. The chromaticity coordinate positions of EuSiN₂ in the CIE 1931 diagram are x = 0.678 and y = 0.284.