KYW sub(2)O sub(8):Eu super(3+) - A closer look on its photoluminescence and structure

High-quality single crystals of partially europium-substituted KYW sub(2)O sub(8) (KYW) were grown by the top-seeded solution growth technique. The structures of four crystals with different europium content were refined on the basis of single crystal X-ray diffractometer data. The trivalent character of europium in these crystals was manifested through super(151)Eu Mossbauer spectra and magnetic susceptibility measurements. Moreover, reflection and photoluminescence spectra were recorded and from these spectra the quantum efficiency, lumen equivalent, and CIE1931 color point were calculated. It turned out that Eu super(3+) doped KYW is an efficient photoluminescent material at room temperature, while the thermal quenching temperature T sub(1/2) is at about 633 K (360 degree C), thus making the material a potential radiation converter for light emitting diodes.