Investigation On Preparation And Properties Of The Oxynitride Green Phosphors For White LEDs

White light-emitting diodes(white LEDs) are regarded as the forth generationgreen lighting source following the incandescent lamp, fluorescent lamp, highintensity discharge, which is the energy converter that converts energy to light energy.Moreover, the main method to achieve the white light is to connect the UltravioletLED chip and three colors of red, green, blue phosphors. The present results showthat there are a lot of excellent red phosphors and blue phosphors. However, theexcellent green phosphors are rare. Therefore, in this paper, the Mn2+,Eu2+-β-SiAlONphosphor and Ln3+-Ba3Si6O12N2:Eu2+are systematically investigated.Mn2+and Eu2+co-doped β-SiAlON green-emitting phosphor has been preparedvia solid state reaction method. The effect of Mn2+doping on the structure andphotoluminescence (PL) properties of β-SiAlON:Eu2+were investigatedsystematically by Rietveld method using GSAS program. The phosphors exhibitedintense broad absorption bands at280-500nm and a broad emission band centeredaround530nm, attributed to4f–5d transitions of Eu2+. The results reveal thatMn2+-doping did not change the lattice structure of β-SiAlON:Eu2+. The emissionintensity of Eu2+ions was greatly enhanced by introducing Mn2+ions intoβ-SiAlON:Eu2+due to the energy transfer from Mn2+to Eu2+. The energy transferprobability from Mn2+to Eu2+depends strongly on the Mn2+concentration, which ismaximized at a Mn2+concentration of3mol%. Also the phosphors show the excellentproperties such as thermal stability.Trivalent lanthanide ions (Ln3+) doped in Ba3Si6O12N2:Eu2+phosphors weresynthesized by solid state reaction method. The X-ray diffraction, morphology and photoluminescence were characterized. The Ln3+ions could significantly improve thephotoluminescence properties of thisoxynitride material which show a green emittinglocated at520nm. The energy transfer of Eu2+, Nd3+co-doped in Ba3Si6O12N2phosphor was observed and then studied systematically. Nd3+doping not only shrinkthe critical distance, but also reduced the probability of non-radiative transitionbetween Nd3+and Eu2+ions, and enhanced green emission intensities of phosphor.This phenomenon was also observed in other lanthanide ions.