Luminescent properties of yellowish orange Y ₃Al _5-xSi _xO _12-xN _x:Ce phosphors and their applications in warm white light-emitting diodes

This paper reports a low-cost yellow-orange emitting Y ₃Al _5-xSi _xO _12-xN _x:Ce ³⁺ phosphor with excellent color rendering for warm white LEDs. It was synthesized by a simple gas pressure sintering (GPS). The effect of Si ⁴⁺N ^3- incorporation on the optical properties of Y ₃Al ₅O ₁₂:Ce ³⁺ phosphor was investigated. The addition of Si ₃N ₄ leads to an obvious shift of its emission spectra toward the red region and an increase of FWHM accompanying a significant decrease of photoluminescent intensity, which is assigned to incorporation of N ^3- in Ce ³⁺ nearest neighbor coordination. Adding nanosized amorphous Si ₃N ₄ or flux can greatly improve the emission intensity of Y _2.925Ce _0.075Al _5-xSi _xO _12-xN _x phosphor. Finally, the white LED flat lamp with a CRI as high as 83, luminous efficiency of 65 lm/W, and CCT of about 3700 K is successfully realized by using a single oxynitride phosphor combined with a blue LED chip, which is acceptable for general indoor illuminations to replace fluorescent or incandescent lamps.