Novel Narrow Band Cyan-Green Phosphor LiK7[Li3SiO4](8):Eu2+ with Enhanced Suppression of Second Broad Band Emission

LiK7[Li3SiO4](8):Eu2+ (LKLSO:Eu2+) was synthesized by a high-temperature solid-state reaction. It is accessible from K2CO3, Li2O, SiO2, and an Eu-source (Eu2O3) by conventional solid-state reaction in nickel crucibles under a constant flow of forming gas. The crystal structure of LKLSO has been determined by single-crystal X-ray diffraction and it crystallizes in the tetragonal space group I41/a (no. 88) with the lattice parameters a=1560.83(5), c=1278.23(4) pm, and a volume of V=0.31140(2) nm(3). The compound is isostructural to NaK7[Li3SiO4](8):Eu2+ but, in contrast, features an enhanced suppression of the second broad band emission through the specific channel filling in the crystal structure. Despite the observed positional disorder in the structure, the cyan-green phosphor shows a narrow band emission with a maximum at 511 nm and a fwhm of 45 nm (0.215 eV).