SYNTHESIS AND PROPERTIES OF EU2+ ACTIVATED BLUE PHOSPHORS

Blue phosphors Eu2+ activated BaMgAl10O17, BaMg2Al16O27, xBaO . 6Al(2) O(3) where x=0.64-1.8 and LaMgAl11O19 have been prepared by the combus tion of corresponding metal nitrates (oxidizer) and carbohydrazide (CH )/diformyl hydrazine (DFH)/urea (fuel) redox mixture at 400/500 degree s C within 5 min. The phosphors were characterized by exposure to UV l ight, powder XRD, fluorescence and electron paramagnetic resonance spe ctroscopy. The phosphors showed a characteristic emission band in the region 435-462 nm when they were excited at 254 nm. With an increase i n barium content in xBaO . 6Al(2)O(3) (x=0.64-1.8) the emission band s howed a red shift. Addition of Mn2+ in Eu2+ doped barium hexa aluminat es and Eu2+ doped LaMgAl11O19 resulted in strong green emission at 515 nm. The fine particle nature of combustion derived phosphors has been studied by powder density (55-82% of theoretical value), particle siz e (5.7-9.5 mu m) and BET surface area (5-22 m(2) g(-1)) measurements.