Preparation And Properties Of Rare Earth Doped Nitroxide Phosphors

Ca Si2O2N2:Eu2+ phosphors were synthesized via the solid-state reaction method. Different silica source was studied as the initial raw materials to final phase structure of synthetic product. Ca2 Si O4 was used as the precursors to synthesize Ca Si2O2N2 : Eu2+ phosphors by the two step method. At 540 nm, two steps to get a sample of the emission intensity of a 120% increase over the one-step method.Ca Si2O2N2:Ce3+ phosphors show a broad band centered at 395 nm under 333 nm excitation. Red-shift occurs as the concentration of Ce3+ increases. The quenching concentration of Ce3+ is approximately 1mol%. Ca Si2O2N2:Eu2+ phosphors emit a single, intense, and broad emission band centered at 540 nm when excited at 397 nm. The quenching concentration of Eu2+ is approximately 1mol%. When excited at 333 nm, the codoped samples Ca0.99-2xSi2O2N2:x Ce3+, x Li+, 0.01Eu2+ emit two broad band centered at 395 nm and 540 nm, respectively. The emission of Eu2+ were significantly enhanced by the increase of Ce3+. When Ca0.98-ySi2O2N2:0.01Ce3+, 0.01Li+, y Eu2+ phosphors were excited at 333 nm, two broad bands, with peaks at 395 and 540 nm, were observed. The former band(at 395 nm)weakened over increasing Eu2+ content. However, the band at 540 nm reached the maximum intensity for y=0.004.These suggest effective energy transfer mechanism from Ce3+ to Eu2+ taking place in the Ca Si2O2N2.The efficiency of energy transfer between Ce3+ and Eu2+ was calculated, and saturation value was occurred when the concentration of Eu2+ increase to 1mol%.The resonance-type energy transfer between Ce3+ and Eu2+ was dipole-dipole interaction mechanism.Finally this paper studies the optimized performance by 1% of La3+ / Gd3+ / Y3+ codoping on Ca Si2O2N2 :0.01Eu2+ phosphor. After codoping La3+, luminous intensity increased by 30%, Gd3+ by 67%, Y3+ by 60%.