Synthesis, Microstructure And Photoluminescence Of Titanate Red Phosphor For White LED

LED is regarded as the fourth-generation solid light source due to its advantages as smallvolume, fast response, non-pollution, long service life. It has been considered to be the maintrend to fabricate LEDs by combining blue LED chips with yellow phosphors for white lightemission, and some of them have been put into commercial use. But the mentioned LEDsabove usually have drawback of low color rendering index due to lack of red lightcomposition. Two kind of red phosphors which can be excited by near-UV and blue LEDchips were synthesized using soft chemical methods, and their luminescent properties werestudied. GSAS refinement was also performed to determine the correlation between themicrostructure and luminescence properties.CaTiO3:(Eu3+, Al3+) phosphors were synthesized by calcining the precursor obtained bysol-gel method at900oC for4h. The main excitations of these phosphors are located at396nm and465nm, and the main emission is located at616nm which can be attributed to the5D0â†'7F2transition, showing that the phosphors have good red emission. The sample obtained atthe Eu3+doping concentration3mol%and Al3+doping concentration0.4mol%is welldispersed with good color index.NaLaTi2O6:Eu3+red phosphors were synthesized by calcining precursor obtained viahydrothermal method at180oC for6h. The as-prepared phosphors can be effectively excitedby465nm blue light, and the main emission is located at616nm, which is induced by theEu3+5D0â†'7F2transition. The luminescent intensity of NaLaTi2O6:Eu3+reaches maximumwhen Eu3+concentration is5mol%. Excited by465nm blue light, the emission at596nm and616nm are both very strong, and the intensity ratio of the above emission is small, showingthat Eu3+occupies well symmetrical site in the crystal. GSAS refinment reveals the correlationbetween the microstructure distortions with the luminescence property, which is a helpfuldiscussion for developing new potential phospors.The NaLaTi2O6:Eu3+and CaTiO3:Eu3+phosphors both exhibit very good luminescenceproperties, showing the potential to be used in white LED. Coparing the influence ofmicrostructure and the particle size to the emission spectra, the particle size ofNaLaTi2O6:Eu3+phosphor synthesized using hydrothermal method are smaller thanCaTiO3:Eu3+phosphor obtained using sol-gel method, and the former has better homogeneity.And the luminescence property of NaLaTi2O6: Eu3+phosphor was influenced mainly bymicrostructure, rather than the particle size; the luminescence property of CaTiO3:Eu3+phosphor was influenced mainly by particle size, not the microstructure.