【作者】 万军；

【导师】 樊先平； 乔旭升；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2017， 博士

【摘要】 与传统光源相比,LED具有节能、高效、体积小、寿命长、响应速度快、驱动电压低以及抗震动等优点,被誉为第四代绿色照明光源。目前,应用于白光LED的荧光粉主要采用固相烧结法制备,制备过程中需要高温烧结和长时间热处理。一方面,固相烧结能耗居高；另一方面,产物严重烧结成粗大颗粒或者密实块体,需要经过球磨粉碎成尺寸不均、形状不规则的细小颗粒,过筛分选后使用。在这些后期处理过程中,常常会引入一些杂质,对荧光粉造成污染,削弱了其发光性能和耐久性能。本课题采用两种不同制备途径分别解决了传统固相烧结法所存在的粉末烧结、能耗居高两项弊病：一、采用环氧丙烷驱动的快速溶胶-凝胶法制备出非晶态Al203微球前驱体,随后在NH3气氛中氮化还原,制得高纯度、高结晶度、形貌规整、粒径可调的单分散AlN微球。在此基础上,延伸制备出280 nm紫外光激发产生605 nm红光发射的AlN：Mn2+微球、365 nm紫外光激发产生520 nm绿光发射的SrAl2O4:Eu2+笼形微球、330 nm紫外光激发产生440nm蓝光发射的CaAl2O4:E u2+微球以及326nm紫外光激发产生651 nm红光发射的Sr2MgAl22O36:Mn4+微球。其中,SrAl2O4:Eu2+绿色笼形荧光微球与CaAl2O4:Eu2+蓝色荧光微球具有优异的发光性能,内量子效率分别高达94.94%和92.64%;Sr2MgAl22O36:Mn4+红色荧光微球的内量子效率达到24.91%。结合XRD、SEM、TEM、FTIR以及PL等测试方法对前驱体的制备及热处理过程进行了系统研究,对不同实验条件下所得产物的物相结构、微观形貌及发光性能进行了分析。重点研究了AlN微球形成机理,SrAl2O4:Eu2+笼形微球结构形成机理和发光增强机制,Ca2+不同程度取代Sr2+对CaxSr1-xAl2O4:Eu2+微球发光性能的影响,并探索了热处理制度和发光中心离子掺杂浓度对荧光微球发光性能的影响。二、采用沉淀法制备Al3+的尿素配合物前驱体Al[OC(NH2)2]6Cl3,随后经NH3气氛氮化还原,于800℃的相对低温下制得AlN纳米晶体。以AlN纳米晶体为基础,采用共沉淀法引入Ca2+和发光中心离子,并以纳米Si3N4为核进行包覆。所得前驱体经由NH3气氛氮化还原后,于1000℃的相对低温下制备出303 nm紫外光激发产生500nm绿光发射的Ca2AlSi3O2N5:Eu2+荧光粉,280nm紫外光激发产生630 nm红光发射的Ca2AlSi3O2N5:Mn2+荧光粉以及303 nm紫外光激发产生650nm红光发射的Ca2AlSi3O2N5:Sm3+荧光粉。对金属阳离子的尿素配合物前驱体、Ca2AlSi3O2N5:Eu2+、Ca2AlSi3O2N5:Mn2+以及Ca2AlSi3O2N5:Sm3+进行了XRD、SEM、TEM和PL等多种表征,分析了不同实验条件下所得产物的物相结构、微观形貌及发光性能。重点研究了A1N纳米晶体在相对低温条件下的形成机理,并探索了热处理制度及发光中心掺杂浓度对Ca2AlSi3O2N5:Sm3+荧光粉物相结构、微观形貌和发光性能的影响。更多还原

【Abstract】 Compared with the traditional light source, LED has the advantages of energy saving, high efficiency, small volume, long lifetime, quick response, low driven voltage, anti-vibration and so on. Thus, LED is regarded as the fourth generation green illuminant source. Until now, commercialized phosphors are usually prepared by a conventional solid-state reaction method. This method has a few inherent disadvantages in requiring high calcination temperature and long processing time, which lead to the formation of coarse agglomerated particles. To obtain particles in the size of several microns, extensive ball milling is used to grind the coarse agglomerated particles generally. This process often contaminates the phosphors and decreases their luminescent intensity greatly.In this thesis, two different routes were adopted to get rid of coarse agglomeration of products and high energy consumption induced by the conventional solid-state reaction method respectively.On the one hand, an epoxide-driven rapid sol-gel method was used to synthesize amorphous Al2O3 microspheres as a precursor, and the precursor turned to AlN microspheres after the nitridation reaction in NH3 atmosphere. The as-synthesized monodisperse AlN microspheres show high degree of crystallinity, regular spherical morphology, controllable particle size and narrow particle size distribution. On this basis, UV light excited phosphors including AlN:Mn2+ red light emitting microspheres (excited at 280 run, emitting at 605 nm), SrAl2O4:Eu2+ green light emitting cage-like microspheres (excited at 365 nm, emitting at 520 nm)、CaAl2O4:Eu2+ blue light emitting microspheres (excited at 330 nm, emitting at 440 nm) and Sr2MgAl2O36:Mn4+ red light emitting microspheres (excited at 326 nm, emitting at 651 nm) were successfully prepared and exhibited brilliant luminescent properties. XRD、SEM、TEM、FTIR、PL and other kinds of characterizations were implemented to analyze the microstructure and luminescent properties of both the precursors and the final products. The research focused on the mechanisms of AlN microsphere formation, SrAl2O4:Eu2+ cage-like microsphere formation, luminescence enhancement by cage-like structure microsphere and the influence of Ca2+ concentration on CaxSr1-xAl2O4:Eu2+ luminescence properties. Furthermore, the influences of heat treatment, activator doping contents and other experimental formulations on the luminescent performance of the products were also studied.On the other hand, a precipitation method was adopted to synthesize urea coordination complex of Al3+ cation, and the precursor turned to AlN nanocrystals after the nitridation reaction at merely 800 ℃ in NH3 atmosphere, a much lower temperature than conventional solid-state method. On this basis, Ca2AlSi3O2Ns:Eu2+ green light emitting phosphor (excited at 303 nm, emitting at 500 nm), Ca2AlSi3O2Ns:Mn2+ red light emitting phosphor (excited at 280 nm, emitting at 630 nm) and Ca2AlSi3O2N5:Sm3+ red light emitting phosphor (excited at 303 nm, emitting at 650 nm) were successfully prepared at the temperature as low as 1000℃. XRD、SEM、TEM、 PL and other kinds of characterizations were also carried out to analyze the microstructure and luminescent properties of both the precursors and the final products. The research focused on the mechanisms of nanocrystals formation at a rather low temperature. Furthermore, the influences of heat treatment and activator-doping concentration on the luminescent performance of the products were also studied.更多还原