Fluorescence Properties of Eu3+ Doped in Na5Lu9F32 Single Crystals

Eu3+ ion doped cubic Na5Lu9F32 single crystals with high quality were synthesized by a modified Bridgman method by using a high 70–90 °C/cm temperature gradient for cross solid-liquid interface. The optical spectroscopic investigations of the obtained single crystal were reported for the absorption, excitation and emission. The experimental results show that a strong red emission at 609 nm attributing to the 5D0→7F2 transition of Eu3+ doped Na5Lu9F32 single crystals can be obtained under the excitation of 394 nm light and reach the maximum when the Eu3+ doping concentration is 4mol% in present research. The local covalent is enhanced and symmetry is reduced with the increase of Eu3+ concentrations inferring from the strength parameters Ω2 and Ω4 calculated by their measured emission spectra. The CIE chromaticity coordinates of the 4mol% Eu3+ doped Na5Lu9F32 single crystals are calculated as (x=0.626, y=0.3736), which are close to the NTSC standard values for red (x=0.67, y=0.33). The experimental results reveal that the single crystal can be used as potential red phosphors under near ultraviolet (NUV) light excitation.