Europium Lithosilicates Li₂EuSi₂N₄ and Li₂EuSiO₄─Crystal Structures and Luminescence

High Resolution Image Download MS PowerPoint Slide With Li 2 EuSi 2 N 4, the end member of the solid-solution series set up by substituting the divalent cation in the well-known host materials Li 2 CaSi 2 N 4 and Li 2 SrSi 2 N 4 with Eu(II) could be synthesized and described by means of single-crystal X-ray diffraction and single-grain luminescence spectroscopy. The new compound crystallizes isotypically to Li 2 CaSi 2 N 4 and Li 2 SrSi 2 N 4 in cubic space group Pa 3̅ (no. 205) with a lattice parameter of a = 10.7049(2) Å and a cell volume of V = 1226.73(7) Å 3 . Irradiated with blue light, Li 2 EuSi 2 N 4 exhibits a narrow-band red emission (λ max = 628 nm, 1.97 eV, 15924 cm –1; fwhm = 83 nm, 0.27 eV, 2143 cm –1 ). Also for Li 2 EuSiO 4, the end member of the solid-solution series of Li 2 SrSiO 4 with Sr(II) substituted by Eu(II), luminescence emission could be measured on a single crystal (λ max = 595 nm, 2.05 eV, 16798 cm –1; fwhm = 116 nm, 0.40 eV, 3211 cm –1 ). In this paper, both compounds are being compared with other known members of their solid-solution series regarding structure and luminescence properties.