The Preparation And Characterization Of Ce:YAG Phosphor In Silica Glass For White LED Modules

White light-emitting diodes (LEDs), regarded as the next-generation of solid-statelighting, have shown an intense tendency to be applied in indoor lighting, outdoor lighting andspecial lighting, benefiting from their high efficiency, high reliability, long lifetime and compactsize compared to traditional lamp-based lighting systems. However, with increasing LEDs outputpower for the demand of higher luminous flux for the general lighting, the LED chip operationtemperature increases largely, causing an ageing and yellowing of organic resin or silicone, whichwill consequently cause critical issues concerning the reliability of the white LED modules, suchas luminous efficacy loss, chromaticity shift and short lifetime. Over the past decade, a newconcept of several inorganic solid phosphors based white LED has been brought up, aiming toreplace conventional organic resin or silicone packaging and solve these problems.In this work, we describe the means of one-step spark plasma sintering (SPS) process inrapidly fabricating Ce:YAG phosphor in silica glass (PiSG) directly from commercial Ce:YAGphosphor. The sinterability, microstructures and optical properties are investigated. The resultsshow that the optimal sintering condition is1200/2min,and the main phase of the obtainedphosphor in glass is mother glass, with absorption peak around460nm. And the broad emissionband peaked at530nm excited by460nm at room temperature. in addition, differentphotoluminescence intensity is obtained by the adjustment of the phosphor concentration. The3wt%sample is the best choice and the3wt%sample based LED modules can fall into white light range（0.33，0.38) under800mAcurrent.The obtained PiSG materials are sintered at1000℃for10minutes with uniaxialpressure of50MPa in vacuum. The XRD patterns, microstructure and transmission electronmicroscopy (TEM) of PiSG samples are also confronted with the used Ce:YAG phosphor powderand the results provide evidence that Ce:YAG phosphor can be absolutely preserved in silica glassmatrix without any decomposition reaction. In the PL spectrum of PiSG sample, the broademission band peaked at550nm when excited by460nm. The property of Ce:YAG phosphor wasmaximum preserved in PiSG samples, as high as93.5%.We have also proved that PiSG materials can potentially be used as a top-prioritycandidate to the conventional silicone-based phosphors for white LED modules. All the samples have the narrow455nm blue band and the broad550nm yellow band. The455nm band is due tothe emission of blue LED chips and550nm emission band is due to the fluorescence of the PiSGsamples excited by the blue LED chips. Obviously, increasing phosphor concentration of PiSGsamples leads to550nm yellow luminescence intensity strengthening gradually. The output ofLED module employing3wt%PiSG sample showed in the inset can fall into white light range(X=0.32, Y=0.34), a CCT of5877K and a CRI of69. The luminous efficacy of the3wt%PiSGbased LED module is127.9lm/W, which is higher than what has reported in the literature so far.The luminous efficacy decreased from148lm/W to80lm/W and the radiation power from131mW to4565mW with the increase of current.