Polycrystalline powders of La Ga SiO (LGSi), La Ga GeO (LGGe), and La Ga TiO (LGTi) doped with Eu were studied with respect to their use as luminescent materials in solid state lighting based on light-emitting diodes. The langasites were synthesized with up to 35% of trivalent europium to achieve the highest possible doping amount. According to diffuse reflection measurements the undoped compounds have band gap energies of 4.51 eV (LGSi), 4.54 eV (LGGe) and 4.07 eV (LGTi).
