Synthesis and Luminescence Properties of Amber Emitting La 7 Sr[Si 10 N 19 O 3 ] : Eu 2+ and Syntheses of the Substitutional Variants RE 8-x AE x [Si 10 N 20-x O 2+x ] : Eu 2+ with RE=La, Ce; AE=Ca, Sr, Ba; 0≤x≤2.

The oxonitridosilicate La 7 Sr[Si 10 N 19 O 3 ] : Eu 2+ and its substitutional variants RE 8-x AE x [Si 10 N 20-x O 2+x ] : Eu 2+ with RE=La, Ce; AE=Ca, Sr, Ba and 0≤x≤2 were synthesized starting from REN, SrN/Ca 3 N 2 /Ba 2 N, SiO 2 , amorphous Si 3 N 4 and Eu 2 O 3 as doping agent at 1600 °C in a radiofrequency furnace. The crystal structure of La 7 Sr[Si 10 N 19 O 3 ] was solved and refined based on single-crystal X-ray diffraction data. La 7 Sr[Si 10 N 19 O 3 ] crystallizes in the orthorhombic space group Pmn2 1 (no. 31). The crystal structures of the isotypic compounds RE 8-x AE x [Si 10 N 20-x O 2+x ] were confirmed by Rietveld refinements based on powder X-ray diffraction data using the single-crystal data of La 7 Sr[Si 10 N 19 O 3 ] as starting point. Crystal structure elucidation reveals a 3D network of vertex sharing SiN 4 and SiN 2 (N 1/2-x/4 O 1/2+x/4 ) 2 (0≤x≤2) tetrahedra. When excited with UV to blue light, La 7 Sr[Si 10 N 19 O 3 ] : Eu 2+ shows amber luminescence with λ em =612 nm and fwhm=84 nm/2194 cm -1 , which makes it interesting for application in amber phosphor-converted light emitting diodes.