含有YAG∶Ce3+和CASN∶Eu2+的LED照明多相荧光玻璃陶瓷

采用热压烧结法制备得到了一种掺有YAG∶Ce³⁺黄色荧光粉和CASN∶Eu²⁺红色荧光粉的烧结玻璃陶瓷。利用X射线衍射仪、扫描电子显微镜和荧光光谱仪对比研究了热压烧结后的烧结玻璃陶瓷和烧结前荧光粉的晶体结构和微观形貌方面的变化,结果显示,荧光相在玻璃基质中没有发生聚集现象,且不会被玻璃基质侵蚀,能保持其发光性能。光谱研究和光电参数分析显示,在YAG∶Ce³⁺黄色荧光粉中引入CASN∶Eu²⁺红色荧光粉,可以有效改善其发光性能,其中显色指数最高为90,色温为4 787 K,明显改善了商用LED照明器件色温高,显色指数低等问题。     

易分散球形YAG:Ce3+荧光粉的制备和性能

将微波均相沉淀与喷雾干燥相结合,并添加助熔剂辅助煅烧制备出单相YAG:Ce³⁺荧光粉体,研究了微波均相沉淀与喷雾干燥的共同作用对煅烧条件和YAG:Ce³⁺荧光粉颗粒形貌、分散性和荧光性能的影响。结果表明,这种单相YAG:Ce³⁺荧光粉体具有良好分散性,平均粒径为2μm;将微波均相沉淀与喷雾干燥相结合能制备出分散性好的球形YAG前驱体颗粒;添加NaF助熔剂使煅烧温度降低至1150℃,并得到纯YAG晶相;随着NaF添加量的增加荧光粉结晶度提高、发光强度增强、发射光谱蓝移;NaF添加量（质量分数）为6%时荧光粉的荧光强度最高,且与单一助熔剂比较,H₃BO₃ NaF混合助熔剂能更好的改善YAC:Ce³⁺的荧光性能。     

YAG:Ce纳米荧光粉发光的温度依赖特性

用沉淀法制备了YAG:Ce纳米荧光粉. 用X射线粉末衍射仪 (XRD)、扫描电子显微镜 (SEM) 对粉体煅烧过程的相变和形貌进行了表征. 研究了80～400K范围内, YAG:Ce纳米荧光粉发光和衰减的温度依赖特性. 结果表明, 前躯体由纳米颗粒组成. 900℃煅烧时, 粉体由非晶态直接转变为YAG相. YAG:Ce的发光强度随温度的升高而减弱. YAG:Ce纳米荧光粉的衰减包含两个指数项, 长时间项反映了体相Ce³⁺的荧光衰减, 随着温度的升高不断减小. 短时间项反映了表面Ce³⁺的荧光衰减, 随着温度的升高呈下降趋势, 由于受到表面效应的影响, 中间出现小幅的阶跃.     

黄色荧光粉La3Si6N11∶Ce3+的结构、性能研究及第一性原理计算

运用高温固相法合成掺铈的氮化物荧光粉La₃Si₆N₁₁∶Ce³⁺。采用X射线衍射仪、能谱仪、荧光光谱仪对合成样品的结构、发光性能等进行研究，利用Rietveld方法对其结构精修，并计算了La₃Si₆N₁₁∶Ce³⁺的色坐标、色纯度和色温。结果表明：该荧光粉的色坐标为(0.4165,0.558),落在黄绿光区域，计算得到La_2.82Si₆N₁₁∶Ce_0.18³⁺的色纯度约为92.86%,具有较高的纯度，相关色温为4137K,属于中间色温。通过计算可得掺杂后La₃Si₆N₁₁∶Ce³⁺的带隙值为2.92eV,相对掺杂前略微减少，且La₃Si₆N₁₁∶Ce     

LED用荧光玻璃的制备及性能研究

以行星球磨得到的SiO₂粉体和商用Ce:YAG荧光粉为原料, 采用放电等离子体烧结技术(简称SPS)成功制备块体荧光玻璃。利用XRD、SEM、紫外/可见光分光光度计和荧光光谱仪等研究了Ce:YAG荧光玻璃的物相、显微结构、吸收和发光性能等。研究结果表明: SPS烧结制备的块体荧光玻璃样品主体是非晶相, 同时荧光粉颗粒在玻璃基质中均匀分布, 颗粒大小也未发生变化, 这表明荧光粉晶体在SPS烧结过程中没有发生化学分解反应, 在玻璃基体中得到很好地保存。该荧光玻璃吸收峰在460 nm左右, 发射波长在530 nm左右。通过对不同含量荧光粉的荧光玻璃进行发光性能表征, 发现荧光粉含量为3wt%的荧光玻璃性能最佳, 以此封装的白光LED样品在800 mA电流驱动下, 获得白光输出, 色坐标为(0.33, 0.38)。     

高光效、大功率LEDs/LDs用Ce:YAG透明陶瓷

Ce:YAG透明陶瓷可与蓝光LEDs/LDs复合, 用于大功率白光LEDs/LDs。本研究通过调整Ce:YAG透明陶瓷的厚度和Ce³⁺的掺杂浓度, 将组装器件的发射光谱和色坐标从冷白区调整到暖白区。以高纯(≥99.99%)商业粉体α-Al₂O₃、Y₂O₃、CeO₂为原料, 采用固相反应法制备了(Ce_xY_1-x)₃Al₅O₁₂ (x=0.0005、0.0010、0.0030、0.0050、0.0070和0.0100)透明陶瓷。陶瓷素坯在1750 ℃真空烧结20 h(真空度5.0×10^-5 Pa), 之后在马弗炉中退火1450 ℃×10 h。不同掺杂浓度Ce:YAG陶瓷(厚度分别为0.2、0.4、1.0 mm)在800 nm处的直线透过率均大于79%。Ce:YAG荧光陶瓷的热导率随着测试温度和掺杂浓度的增加而降低。采用有限元方法模拟不同厚度的Ce:YAG陶瓷和LED组装的热分布, 比较了三种封装方式的热分布。将Ce:YAG荧光陶瓷与LEDs/LDs复合, 制备出色坐标分别为(0.3319, 0.3827)和(0.3298, 0.3272)的白光, 发光效率分别为122.4和201.5 lm/W。将Ce:YAG荧光陶瓷和10、50 W商用蓝光LED芯片组合成熟灯具, 可用于商业用途。Ce:YAG透明陶瓷在大功率照明和显示的彩色转换材料应用领域极具潜力。     

Ce3+掺杂Li2O-MgO-Al2O3-SiO2玻璃的结构与荧光猝灭现象

采用熔融淬冷法制备了不同浓度Ce³⁺离子掺杂的20Li₂O-5MgO-20Al₂O₃-55SiO₂玻璃闪烁材料。采用X射线衍射(XRD)、高分辨透射电镜(HRTEM)技术、密度检测等方法研究了玻璃的微观结构随Ce³⁺离子掺杂浓度的变化规律, 采用荧光分光技术检测了玻璃的紫外光致激发光谱(PLE)、发射光谱(PE)。研究结果表明: 在不对称的晶体场作用下, Ce³⁺离子5d能级被劈裂为5个组分; 随着玻璃基质内Ce³⁺离子掺杂浓度增大, 玻璃的非晶化程度加深; 5d能级的劈裂宽度随之增大, 由此导致激发带向低能量端展宽、发射光谱明显红移; Ce³⁺离子的荧光发射强度随Ce³⁺离子掺杂浓度先升高、后降低, 浓度猝灭过程成为其荧光发射效率降低的主要原因。     

实验优化设计中频反应溅射Al2O3:Ce薄膜发光性质研究

为了得到最优发光的薄膜材料成分参数,采用均匀设计和二次通用旋转组合设计相结合的方法建立发光强度与薄膜中氧含量和Ce³⁺ 离子掺杂浓度的回归方程,并用遗传算法求其取最大值时的解。用中频反应磁控溅射技术制备了相应成分的Al₂O₃:Ce非晶薄膜。在320nm光激发下,获得了较理想的发射光谱,对薄膜发光机理分析表明:薄膜的光致发光来自于Ce³⁺ 离子的5d1激发态向基态4f1的两个劈裂能级的跃迁。发光强度强烈的依赖于薄膜的掺杂浓度和氧元素含量。XPS检测表明,Al₂O₃:Ce薄膜中存在Ce³⁺ 。Ce³⁺ 含量和薄膜的化学成分是通过X射线散射能谱(EDS)测量的。薄膜试样的晶体结构应用X射线衍射分析。     

复合钇铝石榴石荧光粉微晶玻璃发光性能影响因素分析

发光玻璃在白光LED照明等技术领域有重要应用,研究发光玻璃可以有效提高LED器件的发光效率。对复合钇铝石榴石(YAG∶Ce)荧光粉磷锌硼系(PZB)微晶玻璃的发光性能影响因素进行了分析研究。利用荧光光谱等表征手段,通过正交实验方法,讨论了基质玻璃成形方式、荧光粉掺入量和烧结气氛等对微晶玻璃发光性能的影响。研究表明,基质玻璃成形方式和荧光粉掺量对微晶玻璃的发光性能有较大影响:水淬法制备的基质玻璃的发光性能优于浇注法制备的基质玻璃;当荧光粉掺量为20%(质量分数)时,相对发光强度最大,而后又趋于下降;而烧结气氛对发光性能影响不大。采用正交实验法,得出微晶玻璃试样的相对发光强度范围为1 081~4 577,各因素对发光强度影响顺序为荧光粉掺量基质玻璃成形方式烧结温度烧结气氛。     

白光LED用Ce:YAG单晶光学性能及封装工艺的研究

采用提拉法生长了白光LED用Ce:YAG单晶, 通过吸收光谱、激发发射光谱和变温光谱对其光学性能和热稳定性进行了表征, 并研究了晶片用于封装白光LED光源中各因素对其光电性能的影响。Ce:YAG晶片能被466 nm波长的蓝光有效激发, 产生500~700 nm范围内的宽发射带。Ce³⁺的4f→5d轨道的跃迁吸收对应于202、219、247.3、347.4和455.5 nm五个吸收峰, 据此量化分裂的5d能级能量, 依次为21954、29154、40437、45662和49505 cm^-1。温度升高, Ce³⁺的²F_7/2能量升高导致了发光强度的降低, 可降低幅度(13.28%)不大, 比肩国家标准且要优于目前商用白光光源的Ce:YAG单晶制白光LED光源的封装工艺, 从芯片、驱动电流、晶片厚度和添加物四方面进行讨论。研究结果表明, Ce:YAG单晶是一种新型白光LED用荧光材料。     

LED用绿色荧光粉的研究进展

白光LED被誉为第四代照明光源,有着显著的节能前景和庞大的应用市场。荧光粉光转换型是未来白光LED发展的主流方向。(近)紫外激发三基色荧光粉的研制具有十分重要的意义。综述了近年来半导体白色发光二极管(WLED)用绿色荧光粉的研究进展,重点推介了性能较好的绿色荧光粉,并展望了LED用绿色荧光粉发展趋势。     

Microstructures and Dielectric Properties of Ba1-xSrxTiO3 Ceramics Doped with B2O3-Li2O Glasses for LTCC Technology Applications

Ba1-xSrxTiO3 ceramics, doped with B2O3-Li2O glasses have been fabricated via a traditional ceramic process at a low sintering temperature of 900 ℃ using liquid-phase sintering aids. The microstructures and di- electric properties of B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have been investigated systemat- ically. The temperature dependence dielectric constant and loss reveals that B2O3-Li2O glasses doped Ba1-xSrxTiO3 ceramics have di?usion phase transformation characteristics. For 5 wt% B2O3-Li2O glasses doped Ba0.55Sr0.45TiO3 composites, the tunability is 15.4% under a dc-applied electric field of 30 kV/cm at 10 kHz; the dielectric loss can be controlled about 0.0025; and the Q value is 286. These composite ceramics sintered at low temperature with suitable dielectric constant, low dielectric loss, relatively high tunability and high Q value are promising candidates for multilayer low-temperature co-fired ceramics (LTCC) and potential microwave tunable devices applications.     

Dy3+-doped nano-glass ceramics comprising NaAlSiO4 and NaY9Si6O26 nanocrystals for white light generation

The radiative emission properties of the Dy³⁺ ions in oxyfluoride glasses and glass ceramics have been investigated for the generation of white light. The X-ray diffraction pattern of the glass ceramics reveals the presence of NaAlSiO₄ nanocrystals along with secondary phase of NaY₉Si₆O₂₆ in the glass matrix after a suitable thermal treatment of the pristine glasses. Intense white light emission has been observed when the samples are excited with 350 nm light. Yellow to blue emission intensity ratios and chromaticity color coordinates have been determined from the visible luminescence spectra. All color coordinates are found to lie in the white region of the chromaticity color diagram proposing the suitability of the present studied materials for color display devices.     

Study of intrinsic white light emission and its components from ZnO-nanorods/<Emphasis Type="Italic">p</Emphasis>-polymer hybrid junctions grown on glass substrates

We report white-light luminescence from ZnO-organic hybrid light emitting diodes grown on glass substrate by low temperature aqueous chemical growth. The configuration used for the hybrid white light emitting diodes (HWLEDs) consists of two-layers of polymers (PEDOT:PSS/PFO) on glass with top ZnO nanorods. Electroluminescence spectra of the HWLEDs demonstrate the combination of emission bands arising from the radiative recombination in polymer and ZnO nanorods. In order to distinguish emission bands we used a Gaussian function to simulate the experimental data. The emitted white light was found to be the superposition of a blue line at 454 nm, a green emission at 540 nm, orange line at 617 nm, and finally a red emission at 680 nm. The transitions causing these emissions are identified and discussed in terms of the energy band diagram of the hybrid junction. Color coordinates measurement of the WLED reveals that the emitted light has a white impression with 70 color rendering index and correlated color temperature 5500 K. Comparison between ITO and aluminum top contacts and its influence on the emitted intensity is also discussed.     

Physical and Thermal Properties of P2O5-Al2O3-BaO-La2O3 Glasses

The physical and thermal properties of P2O5-Al2O3-BaO-La2O3 glasses were investigated. The effects of glass compositions on the transition temperature, thermal expansion coefficient, density, hardness and refractive index of glasses were studied. The highest hardness of the glasses is 4143.891 MPa and the lowest thermal expansion coefficient of the glasses is 71.770×10-7/℃. A phosphate glass with high mechanical strength and good thermal characteristic is obtained.     

用InGaN蓝光LED与YAG荧光粉制造自然白光LED

报导了用国内自行研制的InGaN/GaN蓝光发光二极管（LED）与钇铝石榴石（YAG）荧光粉结合而得的白光发光二极管（W－LED），在室温，正向电压3．5V，正向电流20mA时，W－LED轴向亮度为1cd,CIE色坐标为（0．31，0．38），接近纯白色（0．33，0．33）。     

The effect of glass addition on the dielectric properties of barium strontium titanate

Ba_0.7Sr_0.3TiO₃ (BST) ceramics were prepared by the conventional solid state ceramic route. Different weight percentages of twelve different glasses were added to the calcined BST ceramics and sintered. The structure and microstructure of the sintered materials were investigated by X-ray diffraction and Scanning Electron Microscopic techniques. The low frequency dielectric properties of the glass-ceramic composites were measured using LCR meter. Some of the glasses improved the dielectric properties and considerably lowered the sintering temperature. The glasses were prepared and characterized under identical conditions. Among the different glasses, 1.5 wt% addition of 71ZnO–29B₂O₃ lowered the sintering temperature of BST to 975 °C with a dielectric loss of 9 × 10⁻³ and dielectric constant of 875 at 1 MHz. The curie temperature of BST ceramics was found to shift towards lower temperature with glass addition.     

Ce、Cr∶YAG微晶玻璃的制备及光谱性能研究

目前白光LED在红光波段发射较弱,导致其显色指数偏低,在白光LED用Ce∶YAG微晶玻璃中掺入Cr3+来增强红光波段的发射,从而提高显色指数。通过X射线衍射、荧光光度计、电光源参数测试对样品的晶相、光谱性能及荧光寿命进行了表征。研究了Cr3+对Ce∶YAG微晶玻璃发光性能的影响,并对其增红机理进行了初步的探讨。结果表明基质玻璃在1400℃热处理可析出纯的YAG晶相;Ce∶YAG和Ce、Cr∶YAG微晶玻璃在460nm激发下,在480～650nm产生有效发射,发射光谱中心波长位于530nm;由于Ce3+(2E)-Cr3+(4T)之间的非辐射能量传递,Ce、Cr∶YAG微晶玻璃在688、692和705nm处有红色发射峰,能有效地提高白光LED的显色性能。     

The study of luminescence properties on Ce:YAG phosphor in glass co-sintered at different temperatures

Ce:YAG phosphor in glass was prepared by co-sintering bismuthate glass frits and Ce:YAG phosphors at different temperatures in the 550–800 °C range. In this work, the effect of co-sintering temperature on the photoluminescence and chromaticity coordinates (CIE) of phosphor in glass was investigated. The results show that the CIE coordinates is tunable with the increase of co-sintering temperature. As temperature increased from 550 to 700 °C, the intensity of emission and excited peak increases until a maximum is reached, after which it rapidly drops off. The degradation of luminescence properties with the higher co-sintering temperature is due to the broken lattice surrounding the Ce³⁺ and oxidation of the Ce³⁺ caused by the reactions between the bismuthate glass and Ce:YAG phosphors.     

低温共烧氧化铝/玻璃复合基板材料的研究

以低软化点的钙硼硅酸盐玻璃和氧化铝粉末为原料,制备了氧化铝/玻璃低温共烧复合基板材料。所需的玻璃粉体采用溶胶-凝胶法制备。研究了烧结温度和氧化铝含量对复合材料的烧结特性、介电性能以及力学性能的影响。结果表明,当氧化铝质量分数为50%,复合材料经950℃、保温2 h烧结后,其εr=5.92,tanδ=5.7×10-4,ρ=1012Ω.cm,抗弯强度σ=167.82 MPa,热膨胀系数α=4.86×10-6/℃,可望作为低温共烧多层陶瓷基板材料应用。