白光LED荧光粉研究及应用新进展

基于白光发光二极管技术的迅速发展以及荧光粉对白光LED器件的发光效率、显色性和使用寿命等性能的决定性影响,系统阐述了蓝光LED芯片激发用铝酸盐、硅酸盐、氮化物和氮氧化物系列黄色、红色和绿色荧光粉的研究进展和应用现状。探讨了上述荧光粉的研究重点、发展趋势和应用前景,指出需要进一步提高铝酸盐黄粉的发光效率,开发新型高光效氮化物和氮氧化物红粉和绿粉及其低成本制备技术,以满足高光效、高显色、低光衰型白光LED器件制作需要。     

Preparation and luminescence properties of the red-emitting phosphor（Sr1-xCax）2Si5N8：Eu^2＋ with different Sr/Ca ratios

A series of Eu2+-doped ternary nitride phosphors, with a formula of (Sr1-xCax)2Si5N8: Eu2+, were synthesized by high-temperature solid-state method. The structure and luminescence properties were characterized, indicating the potential application as a red phosphor in the phosphor-converted white light-emitting diodes. The X-ray diffraction patterns showed that the Sr2Si5N8 and Ca2Si5N8 phases were generated at each end of (Sr1-xCax)2Si5N8: Eu2+ and coexisted in the range of 0.5≤x≤0.75. The emission spectra showed broad emission bands originating from the 4f65d1→4f7 transition of Eu2+ ions. The emission peak changed with the variations in Ca2+ concentration.     

Sr_(1-x)Al_(1+y)Si_(4-y)N_(7-y)O_y:xEu~(2+)橙色荧光粉的合成及发光特性研究

采用常压高温固相法合成一种新型的氮氧化物橙色荧光粉SrAl1+ySi4-yN7-yOy:Eu2+。结合X射线衍射(XRD)、扫描电镜(SEM)和荧光光谱等分析手段,研究了荧光粉的组分配比变化对其物相结构的影响,结果发现当0≤y≤0.225时,该物质属于SrAlSi4N7结构。结合对离子半径及晶格常数变化等的分析,推断晶格中氧是以Al-O键取代了晶格中的Si-N键的方式而存在。通过对该荧光粉的光色特性研究发现,SrAl1+ySi4-yN7-yOy:Eu2+荧光粉可被近紫外到可见光有效激发,产生580~600 nm的橙光发射。对比Sr0.9Al1.225Si3.775N6.775O0.225:Eu0.1荧光粉和Sr0.9AlSi4N7:Eu0.1荧光粉的斯托克斯位移发现,Al-O的引入使得Sr0.9Al1.225Si3.775N6.775O0.225:Eu0.1荧光粉的非辐射弛豫几率相对较小,从而具有相对更高的热稳定性。因此,SrAl1+ySi4-yN7-yOy:Eu系列荧光粉是一款颇具前景的白光LED用橙色荧光粉。     

Synthesis and luminescence properties of Sr3-z（AlxSi1-x）O5-xFx：zCe^3＋phosphors

Sr3-z(Alx,Si1-x)O -5-xFx:zCe3+ phosphors were synthesized by high-temperature solid-state reaction.The structure and luminescence properties of phosphors with various Al/Si ratios and Ce3+ concentrations were characterized using various methods such as X-ray diffraction,photoluminescence excitation and photoluminescence spectra.XRD result displayed that a complete solid solution between Sr3AlO4F and Sr3SiO5 was formed.With the increasing of x value,a broader excitation band and stronger absorption appeared in the blue light region.Moreover,the emission band shifted to a shorter wavelength and the emission intensity reached a maximum at x=0.6.By adjusting the concentration of Ce3+,a widely tunable range of emission wavelength under the excitation of 460 nm was obtained from the green to yellow regions.In addition,the concentration and thermal quenching were also discussed.     

白光LED用高效荧光转化材料钪硅酸盐的研究进展

由于目前LED用绿色荧光粉体系分别存在热稳定性差、显色指数低、制备复杂苛刻等问题,因此日本三菱化学开发出了一种新型LED用绿色Ca3Sc2Si3O12∶Ce3+钪硅酸盐荧光粉。在综述Ca3Sc2Si3O12∶Ce3+荧光性能的基础上,总结分析了Ca3Sc2Si3O12∶Ce3+荧光发光材料的晶体结构和发光机制,表明这种荧光粉兼备了硅酸盐和YAG∶Ce荧光粉的石榴石结构,使得晶体场能够与Ce3+配合展现出良好的匹配性,可以很好的与现行蓝光芯片匹配得到高品质的白光,并且类似YAG晶体的石榴石结构有着良好的发光性能和热稳定性;讨论了在电荷补偿作用和这种作用下基质改变后荧光粉的性能变化,以及激活剂改变、能量传递的影响,表明荧光粉光色可调幅度较大,能够根据不同变化产生不同的发光;然后分固相法和液相法总结了该荧光粉的制备方法,证明该荧光粉烧结温度低、合成工艺适应性广泛,并且高温固相法是工业化生产该系列荧光粉的最佳方法;最后展望了Ca3Sc2Si3O12∶Ce3+荧光转换材料的发展趋势和在白光LED中的应用前景,作为一种新型高效的白光LED用绿色荧光粉,需要进一步的研究和探索。     

Spectral variations of Ca3Sc2Si3O12:Ce phosphors via substitution and energy transfer

The luminescence intensity of emission peak at around 525 nm decreased in the Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphors. Mg2+ ion, which was likely incorporated into the Sc3+ position of the host crystal, was co-doped to adjust the crystal field and compensate for the excess positive charge due to the doping of Ce3+. The green emission belonged to the 5d→4f transition of Ce3+ moved toward longer wavelength by addition of Mg2+ in Ce3+ and Er3+ co-doped Ca3Sc2Si3O12 phosphor, which could increase the brightness of the phosphor. However, the position of weakening of luminescence intensity at around 525 nm remained basically unchanged by increasing the amount of Mg2+. The results showed that the weakening of luminescence intensity at around 525 nm caused by the absorption of Er3+, which had little influence on the environment of the crystal field.     

照明及显示用稀土发光材料

稀土发光材料是稀土最为重要的应用之一。详述了新型绿色照明及平板显示用稀土发光材料发展历程,重点介绍了照明、显示用稀土发光材料的种类、技术及市场状况,介绍了中国在高端稀土发光材料领域关键技术及核心知识产权缺乏、产品品质不高等问题,阐述了中国稀土发光材料下一步的研发和产业重点,重点发展全光谱照明、广色域液晶显示、大功率照明、红外探测以及植物照明用稀土发光材料。     

Effect of SiN substituting for AI-O bonds on luminescence properties of Sr3AIO4F：Ce3＋ phosphor

Cerium-doped Sr3（A11-x,Six）O4-xNxF oxynitride phosphors with different x values were synthesized by solid-state reaction. The structure and optical properties of these phosphors were investigated by X-ray diffraction （XRD）, energy dispersive spectroscopy （EDS） and photoluminescence （PL） spectra. The XRD results showed that SiN substitution for Al-O） did not change the structure of Sr3A104F host and there was no impurity for x〈0.6. With the increasing ofx values, the absorption of phosphors at the blue region was enhanced and the emitting band varied from 519 to 529 nm under the 460 nm blue light excitation. The red shift of the emission band was associated with an increase in the crystal-field splitting and the covalence, which arose from the incorporation of N. More- over, the incorporation of N also improved the thermal quenching properties and the external quantum efficiency with a maximum value up to 43.3%, indicating that this phosphor is a promising candidate for white LEDs application.     

柬埔寨王国菩萨省Svay山区镍矿地质特征及找矿前景分析

柬埔寨王国菩萨省Svay山区镍矿区位于豆蔻山-大叻断褶带上,是重要的有色金属、贵金属成矿带,属于地球低磁纬度区域。地表发现了8条呈长条带状、透镜状、囊状等展布的镍矿带。经高精度磁法测量,镍矿带出露区域ΔT负磁异常明显,且强度高、范围大,明显有别于中纬度地区的矿致高磁正值异常。良好的物探异常和优越的成矿环境,指出该区域内具有较好的找矿前景。     

荧光粉在高显色性白光LED中的应用研究

本文研究了由GaN基蓝光芯片和不同颜色荧光粉组成的三个白光LED系统,提出了改善白光LED显色性的解决方案。研究结果表明,在蓝光LED芯片与黄粉系统中,在一定范围内,随着粉胶比浓度逐渐减小,即增加蓝光出光量,显色指数会逐渐增加,光效持续降低;当采用黄粉和红粉时,发现不仅要观察基本的R1-R8值,还要考查R9-R15值,通过优化黄粉和红粉的比例,可以得到显色指数为81.3的暖白光LED;进一步要使暖白光LED的显色指数达到90或以上,同时又要维持较高的发光效率,证明可以通过采用黄粉＋红粉＋绿粉来代替只用红粉＋绿粉的系统来实现。