Synthesis and Luminescence Properties of Amber Emitting La7 Sr[Si10 N19 O3 ] : Eu2+ and Syntheses of the Substitutional Variants RE8-x AEx [Si10 N20-x O2+x ] : Eu2+ with RE=La, Ce; AE=Ca, Sr, Ba; 0≤x≤2.

ABSTRACT

The oxonitridosilicate La7 Sr[Si10 N19 O3 ] Eu2+ and its substitutional variants RE8-x AEx [Si10 N20-x O2+x ] Eu2+ with RE=La, Ce; AE=Ca, Sr, Ba and 0≤x≤2 were synthesized starting from REN, SrN/Ca3 N2 /Ba2 N, SiO2 , amorphous Si3 N4 and Eu2 O3 as doping agent at 1600 °C in a radiofrequency furnace. The crystal structure of La7 Sr[Si10 N19 O3 ] was solved and refined based on single-crystal X-ray diffraction data. La7 Sr[Si10 N19 O3 ] crystallizes in the orthorhombic space group Pmn21 (no. 31). The crystal structures of the isotypic compounds RE8-x AEx [Si10 N20-x O2+x ] were confirmed by Rietveld refinements based on powder X-ray diffraction data using the single-crystal data of La7 Sr[Si10 N19 O3 ] as starting point. Crystal structure elucidation reveals a 3D network of vertex sharing SiN4 and SiN2 (N1/2-x/4 O1/2+x/4 )2 (0≤x≤2) tetrahedra. When excited with UV to blue light, La7 Sr[Si10 N19 O3 ] Eu2+ shows amber luminescence with λem =612 nm and fwhm=84 nm/2194 cm-1 , which makes it interesting for application in amber phosphor-converted light emitting diodes.