YAG：Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

The sub-micron sized YAG ： Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors.     

多孔介质孔隙结构的网络模型应用

本研究分别用毛细管束模型和网络模型对多孔介质的孔构型进行描述。为了克服毛细管束模型在反映真实结构存在的局限性,有必要发展更为精确的方法,在诸多的多孔介质模型中,网络模型经过多年的研究、发展,已经可以较好地实现对过程机理进行定量预测,进一步通过引入非线形分形理论,对复杂孔隙结构可望得到更为真实可靠的构型模型。     

YAG∶Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route

Whitelight emittingdiodes(WLED)arepoised forrevolutionizingtheluminescencelightingindustry,andhavethepotentialofreplacingtheconventionalin candescentanddischarge column typefluorescent lampsforhighefficiency,longlifetime,nopollution,fullsolid statelampetc.Todate,theblueLEDchip combinedwithyellowceriumdopedyttriumaluminum garnetphosphors(YAG∶Ce)isthemostcommonpat terntoproducewhitelight[1].Traditionally,theYAGphosphorispreparedby solid statereactionsusingsolidchemicalsofY2O3and Al2O3ass…     

由Miedema生成热关联多元体系组元的活度系数

为满足实际应用中二元及多元液态合金体系的热力学数据的需要，对基于元素本性的Ｍｉｅｄｅｍａ生成热计算模型进行描述，建立适于液态和固态溶液合金组元的活度系数关系式，并通过对三个二元系过剩热力学性质的推广，得出与三元系活度相关联的热力学关系式。     

铝腮二元有序溶液的热力学性质

运用Ｐｅｌｔｏｎ和Ｂｌａｎｄｅｒ的修正似化学理论，分析了具有实际指导意义的Ａｌ－Ｓｒ二元系溶液的有序性特征并进行了热力学计算．在二元系的富铝端，形成的高熔点Ａｌ４Ｓｒ化合物是铝锶液态阴极熔盐电解过程中发生“钝化”现象的根本原因．     

NaCl－KCl熔盐系中硫化铅直接电解研究

报道了硫化铅在等摩尔ＮａＣｌ－ＫＣｌ及ＮａＣｌ－ＫＣｌ－Ｎａ＿２Ｓ熔盐体系中直接电解的初步研究结果。     

Fluorescence enhancement of single-phase red-blue emitting Ba3MgSi2O8:Eu2+,Mn2+ phosphors via Dy3+ addition for plant cultivation

Fluorescence enhancement of red and blue concurrently emitting Ba₃MgSi₂O₈:Eu²⁺,Mn²⁺ phosphors for plant cultivation has been investigated by Dy³⁺ addition. The Ba₃MgSi₂O₈:Eu²⁺,Mn²⁺,Dy³⁺(BMS-EMD) phosphors have two-color emissions at the wavelength peak values of 437 nm and 620 nm at the excitation of 350 nm. The two emission bands are coincident with the absorption spectrum for photosynthesis of plants. An obvious enhancement effect has been observed upon addition of Dy³⁺ with amount of 0.03 mol%, in which the intensities of both blue and red bands reach a maximum. The origin of red and blue emission bands is analysed. The photochromic parameters of the samples at the nearly UV excitation are tested. This fluoresence enhancement is of great significance for special solid state lighting equipment used in plant cultivation. This work has been supported by National Natural Science Foundation of China (Grant No 50872091) and the Natural Science Foundation of Tianjin, China (06YFJMJC02300, 06TXTJJC14602).     

Thermal stability of luminous YAG: Ce bulk ceramic as a remote phosphor prepared through silica-stabilizing valence of activator in air

A prototype of YAG: Ce (Y3Al5O12) luminous bulk ceramic as a remote phosphor for white LED illumination was fabricated in air through a strategy of silica addition. With increasing the amount of silica in a specific range, the opaque sample turns to be semi-transparent. The precipitation of crystals is verified to be in pure YAG phase by X-ray diffraction (XRD). Beyond the limit of silica amount, the dominant phase of YAG crystal is found to coexist with a small amount of newly-formed Y2Si2O7, Al2O3 and the amorphous phase. The YAG crystals are with a grain size of approximately 2 mm and distribute evenly. The YAG hosts after structural modification via addition of silica result in yellow band emission of 5d→4f transition peaked around 535 nm as excited by a blue LED, owing to the self-reduction of Ce4+ to Ce3+ even in the absence of reductive atmosphere.     

铝/飞灰颗粒复合材料液相烧结过程的反应性

以煤飞灰颗粒为增强相, 用液态烧结粉末冶金方法, 制备了铝/飞灰复合材料. 用热力学数据库分析考察了液相烧结过程中的反应性和新生成相.用XRD分析方法结合扫描电镜, 研究发现飞灰中的部分成分与液态铝进行了反应, 形成了单质Si, Fe, Ti以及Al和Si, Fe, Ti的金属间化合物. 反应的发生导致了飞灰颗粒的非晶态及反应特性的改变.     

Tb3+,Mn2+作为激活剂的PDP绿色荧光粉的研究

分别介绍了以Mn^2＋和Tb^3＋作为激活中心的PDP用硅酸盐体系、铝酸盐体系、硼酸盐体系和磷酸盐等体系绿色荧光粉的研究现状。在以Mn^2＋作为发光中心的绿粉中，目前研究主要集中在通过调整Mn^2＋的离子浓度、添加其他杂质，探索使用新的基质材料，或是使用不同的合成技术等方法来改进其余辉时间过长、易时效劣化以及形貌上的不足。在以Tb^3＋作为激活中心的绿粉中，为了获取在真空紫外激发条件下高的发光效率，则主要围绕寻找在VUV区域内有强吸收的基质和能够有效进行能量传递的稀土敏化剂，以及利用量子剪裁效应来使得荧光粉发光量子效率大于1等方面进行。