Investigation On Rare-Earth-Doped White Light Emitting Transparent Glass-ceramics

White light-emitting diodes （LEDs） have been used more and morewidely in lighting, back light, automobile, display and business, etc, because of thehigh brightness, long lifetime, low power consumption, and little volume comparedwith the conventional light bulbs and fluorescent lamps. At Present, the commercialLED has poor heat-resistance due to their packing with organic resins. So it isessential to develop a novel material to improve these problems. Glass ceramics forthe short Manufacturing cycle, simple Preparation technology, Rare earth ionsdistribute equality, Luminous color coordinates is easy to control etc, which make theglass ceramics become very good white light LED materials, have been extensiveresearched In recent years. In this paper, new rare-earth-doped silicate glass ceramicsfor white light emitting diodes under UV light excitation were prepared. Theirluminescence properties and Fluorescent life have been studied.The Matrix component, preparation process, heat treatment process, etc ofBaYF₅glass ceramics have been researched. The glass ceramics of different Ce³⁺ions and Tb³⁺ions doping concentration have been prepared. Heat treatmenttemperature and Ce³⁺ions doping concentration on the influence of the luminescenceproperties of Ce³⁺ions have been researched. The results show that Heat treatmenttemperature and Ce³⁺ions doping concentration only affect the luminous intensity.With an excitation at338nm, a broad asymmetric band at462nm due to the5d1â†'4f1transition was observed. The blue emission（487nm）,green emission （542nm）,orangeemission（582nm） and red emission （620nm） assigned to5D4â†'7FJ（J=6,5,4,3）transition ofTb³⁺ions respectively are simultaneously observed at room temperature under365nmexcitation in the Tb³⁺doped glass ceramicsA new Ce³⁺/Tb³⁺co-doped BaYF₅glass ceramics were prepared theLuminescence properties, energy transfer from Ce³⁺to Tb³⁺and fluorescence lifetimehave been researched. By adjusting the doping ratio of Ce³⁺and Tb³⁺got white light emitting, the optimal composition generates white light with chromaticity coordinates（0.287,0.336）, color temperature was8000K, color rendering index Ra was65, andquantum efficiency was80%and radiation efficiency25%.The preparation and heat treatment technology of β-Zn₂SiO₄glass-ceramicshave been researched. Sm³⁺doped and Ce³⁺/Sm³⁺co-doped glass ceramics wereprepared. Luminescence properties, energy transfer from Ce³⁺to Sm³⁺andfluorescence lifetime have been researched. By adjusting the doping ratio of Ce³⁺andSm³⁺got white light emitting, the optimal composition generates white light withchromaticity coordinates （0.315,0.296）, color temperature was7200K, colorrendering index Ra was70, quantum efficiency was72%and radiation efficiency18%; To get More ideal white light luminous glass ceramics, The Ce³⁺/Sm³⁺/Tb³⁺co-doped glass–ceramics were prepared. The optimal composition generates whitelight with chromaticity coordinates （0.340,0.334）, color temperature was5800K,color rendering index Ra was75, and quantum efficiency was75%and radiationefficiency20%.Eu³⁺/Eu²⁺co-doped β-Zn₂SiO₄glass-ceramics were prepared, researched theeffect of heat treatment temperature on the transformation of Eu³⁺to Eu²⁺. More andmore Eu³⁺changed to Eu²⁺as the heat treatment temperature increased. The colorcoordinates of the emission spectrum distribute in yellow area, nearly white area andblue area. According to this phenomenon, we can control the heat treatmenttemperature to get single rare earth ions doped white light emitting transparentglass-ceramics in theory.