PDP红色荧光粉的制备动态

阐述了现有PDP红色荧光粉存在的问题,并重点从改进生产工艺和制备纳米级红色荧光粉对近几年改善PDP红色荧光粉质量的相关研究工作进行了阐述.     

白光LED用红色荧光粉的制备及性能研究

采用溶胶-凝胶法合成了可用于395 nm及465 nm激发的Ca1-2xBxEu MoO4 (B=Li+,Na+,K+)红色荧光粉.用XRD和荧光光谱对其结构、发光性能进行了表征,并就不同电荷补偿对其发光性能的影响进行了分析.同时研究了煅烧温度及Eu3+浓度对所得荧光粉发光性能的影响.     

LED照明用红色荧光粉的制备工艺研究进展

红色荧光粉是白光LED照明应用中的一种关键发光材料,一直是人们研究的重点.合成红色荧光粉最主要方法是高温固相法.为了降低合成温度、优化性能和降低成本,其合成方法先后出现了溶胶-凝胶法、沉淀法、水热法、微波法和燃烧法等.目前在"紫外或紫外光LED+RGB荧光粉"的方法中,红、绿、蓝三种荧光粉的效率都有较大的提高,但红色荧...     

共沉淀法合成CaO:Eu~(3+)红色荧光粉的研究

采用共沉淀法合成CaO:Eu3+红色荧光粉,探讨了Eu3+离子的掺杂量、煅烧温度和煅烧时间对样品发光性能的影响,并利用X-射线衍射仪(XRD)、扫描电镜(SEM)和荧光光度仪(PL-PLE)等仪器对样品的性能进行表征.结果表明:掺杂Eu3+作为发光中心进入到CaO基质的晶格中,其最佳掺杂量为1.5%(摩尔含量);最佳煅烧温度和煅烧时间分别为1100℃和4h,样品的激发峰位于200~290nm之间,对应于Eu3+-O2-的电荷迁移跃迁(CTB),属于宽带激发;Eu3+离子主要占据严格对称的格位,其最大发射峰位于592nm,对应于5D0→7F1磁偶极跃迁,属于红色发光.     

低温共沉淀法合成红色荧光粉CaCO3:Eu3+

采用低温共沉淀法直接合成红色荧光粉CaCO3:Eu3+,利用X射线衍射(XRD),电子扫描电镜(SEM)和荧光光谱(PL-PLE)等仪器对样品的结构、形貌和发光性质进行表征.同时,研究了反应温度和Eu3+离子掺杂量对样品性能的影响.结果表明:通过改变工艺条件可以合成球形、立方体和针状等不同形貌的样品.Eu3+作为发光中心进入到文石型或方解石型CaCO3的晶格中,其最佳掺杂量1.0%(摩尔分数).激发峰主要由电荷迁移态和Eu3+离子的特征激发跃迁组成.发射峰以电偶极跃迁5D0→7F2为主,Eu3+离子未处于严格对称的格位.样品的形貌,结晶度和物相均对发光强度有较大的影响,光滑的针状的文石型样品的发光强度最高.反应温度不同,样品的发光强度不同,其最佳的反应温度为60℃.     

铝酸盐红色荧光粉研究进展

综述了铝酸盐红色荧光粉的研究进展,简要介绍了铝酸盐的相组成以及制备方法,着重介绍了几种在不同基质材料中的荧光粉的发光特性,并对今后的研究方向进行了展望.     

PDP用YGB红色荧光粉的制备技术研究现状

介绍YGB((Y,Gd)BO3:Eu3+)红色荧光粉的结构和发光性能,综述近年来YGB荧光粉制备技术方面的新进展,比较不同制备方法的优缺点,探讨了YGB红色荧光粉当前存在的问题,并展望YGB红色荧光粉制备技术的发展趋势。     

PEG对Ca0.68Mg0.2SiO3:0.12Eu3+红色荧光粉形貌及发光性能影响的研究

采用化学共沉淀法一次煅烧制备红色荧光粉Ca0.68Mg0.2SiO3∶0.12Eu3+的基质材料,借鉴表面扩散原理对红粉进行铕元素掺杂。用X射线衍射仪、荧光分光光度计和扫描电子显微镜对试样的晶体结构,发光性能及表面形貌进行了表征,进而研究了PEG的添加量对粉体形貌及发光性能的影响。结果表明:制得的基质粉末为CaSiO3,并含有少量的CaMg(SiO3)2,PEG的添加对样品结构有一定影响。与此同时可有效提高粉体的分散度和分布均匀性,改善粒子的形貌,荧光粉的发光强度随PEG的添加量增加出现了先增加后减小的趋势,这是因为PEG的量过多,影响了Eu3+及Mg2+取代Ca1、Ca2、Ca3格位,尽管晶体结构趋于完整,也不利于样品的发光。PEG的最佳添加量为样品质量的1%,此时粉体粒子直径约1.3~1.5μm,为类球状,PEG的添加大大提高了荧光粉的发光强度。     

白光LED用红色荧光粉的研究进展

白光LED具有低压、低功耗、高可靠性和长寿命等一系列优点,是一种符合节能环保的绿色照明光源.现阶段的白光LED显色指数低、色温较高,限制了白光LED在室内照明等领域的发展,而红色荧光粉能对白光LED的显色指数的提高及色温的改善影响极其显著.主要介绍白光LED用红色荧光粉几大主要体系的发光性质及最新发展现状.     

白光LED用稀土红色荧光粉的研究进展

白光LED具有低压、低功耗、高可靠性和长寿命等一系列优点,是一种符合环保和节能的绿色照明光源。现阶段制造高显色指数、低色温,大功率白光LED是白光LED发展的总体趋势。而红色荧光粉性能对白光LED的显色指数及色温的影响极其显著。本方法着重介绍和评述了白光LED用红色荧光粉硫化物、氮化物、钼酸盐和钨酸盐等几大主要体系的发光性质及最新研究成果和发展现状,并对白光LED用荧光粉的发展进行了展望。     

钒硼酸钇铕荧光粉的真空紫外光谱特性研究

采用高温固相法合成了YBχV1-χO4-χ：Eu^3＋荧光粉,利用XRD变温发射光谱以及真空紫外激发的光谱对其进行研究。结果表明,在147nm的真空紫外光激发下,荧光粉的发射主峰位于619nm,与（Y,Gd）BO3：Eu^3＋相比,色纯度较好,发光亮度达86％,是彩色PDP用红色荧光粉的候选材料。     

Microwave properties of vanadium borate glasses

A.c. conductivity, dielectric constant and loss, and variation with temperature (302–373 K) for four different compositions of V₂O₅-B₂O₃ glasses were reported at 9.586 GHz microwave frequency. The quality factor (Q) and attenuation factor (α being the important parameters in the microwave range of applications were also studied. The change in the dielectric constant and loss was observed with composition of V₂O₅. The maximum loss was found to be at 15V₂O₅ mol‰ The peak was observed in loss with temperature.     

Thermodynamics of oxidation-reduction of vanadium in borate glasses

The V⁴⁺ V⁵⁺ equilibrium in a 2BaO-3B₂O₃ glass has been studied as functions of temperature, at a fixed partial pressure of oxygen, and total vanadium concentration of the melt. The optical and esr spectra of some of these glasses have also been studied to characterize the V⁴⁺ and V⁵⁺ centres. From the linear temperature dependence of the redox concentration ratio, the activation energy for the redox reaction has been determined at each concentration. The plot of logarithm of the ratio of the activity coefficients and also of the enthalpy of the redox reaction against composition showed considerable changes around 22 mol% V₂O₅. Structural changes associated with both V⁴⁺ and V⁵⁺ ions are suggested to account for such behaviour, which was also suggested from a previous study of the conductivity behaviour of such glasses. The optical and esr spectra showed considerable changes in the V⁴⁺-O and V⁵⁺-O bonding, but no sudden change was observed around 22 mol% V₂O₅.     

PL and EL properties of Tm-activated vanadium oxide-based phosphor thin films

The preparation of high-luminance blue emitting Tm-activated multicomponent oxide phosphor thin films is described. The phosphor thin films were deposited on thick BaTiO₃ ceramic sheets by r.f. magnetron sputtering using powder targets. A very high photoluminescence (PL) intensity in blue emission could be observed in postannealed Tm-activated gadolinium oxide-vanadium oxide Gd_0.5-V_0.5-O:Tm thin films prepared using Tm₂O₃-doped (Gd₂O₃)_0.5-(V₂O₅)_0.5 targets (V₂O₅ content of 50 mol.%). It should be noted that thin films of this phosphor postannealed at 1100 °C in air exhibited higher PL intensity than those from commercially available blue BaMgAl₁₄O₂₃:Eu (BAM) phosphor powder and Gd_0.5-V_0.5-O:Tm powders. In addition, a Gd_0.5-V_0.5-O:Tm thin-film electroluminescent device exhibited a blue emission that was the same as the PL emission.     

Luminescent properties of a novel green-emitting gallium borate phosphor under vacuum ultraviolet excitation

Vacuum ultraviolet (VUV) excitation and emission properties of a new Tb³⁺-activated green-emitting phosphor with huntite-type gallium borate, LnGa₃(BO₃)₄:Tb³⁺ (Ln = Y, Gd), are investigated. Overall absorption bands are in the range of 120-250 nm and can be tentatively interpreted in terms of the charge transfer transition from host to rare earth ions and the Tb³⁺ activator. Additionally, an appropriate atomic ratio of Y³⁺/Gd³⁺ in the host compound enhances both the excitation and emission efficiency under VUV excitation. Enhanced absorption efficiency for the VUV light makes these novel phosphors the prominent luminescent materials with plasma-discharge conditions, by converting the VUV radiation to the visible light.     

Effect of preparation temperature on the characteristics of Eu-doped borate phosphor particles in the spray pyrolysis

Eu-doped gadolinium borate (GdBO₃:Eu) phosphor particles with fine size and uniform morphology were prepared by spray pyrolysis. The effects of the preparation temperatures on the characteristics of the GdBO₃:Eu phosphor particles prepared by spray pyrolysis were analyzed. The precursor particles obtained at preparation temperatures below 1400 °C had hollow and porous inner structures. On the other hand, the precursor particles obtained at preparation temperature of 1600 °C had dense structure and uniform morphologies. The precursor particles with glass phases were formed at high-preparation temperatures above 1400 °C. The precursor particles prepared at preparation temperature of 1400 °C turned into GdBO₃:Eu phosphor particles with fine size and regular morphology after post-treatment. The GdBO₃:Eu phosphor particles prepared from the precursor particles obtained at a preparation temperature of 1400 °C had the maximum photoluminescence intensity, which was similar to that of the commercial (Y,Gd)BO₃:Eu phosphor particles.     

Optical and esr spectra of vanadium (IV) in different simple germanate,phosphate and borate glasses

The optical and esr spectra of some Na₂O-GeO₂, Na₂O-P₂O₅, Na₂O-CaO-P₂O₅ and Na₂O-Al₂O₃-B₂O₃ glasses containing vanadium(IV) have been studied; these spectra have been analyzed by assuming that vanadium(IV) is present as the vanadyl ion in a ligand field of C_4V symmetry. It has been found that in Na₂O-GeO₂ and Na₂O-P₂O₅ glasses the covalency in the in-plane V-O δ-bonds increases, and the degree ofπ-bonding with the vanadyl oxygen decreases, with increasing Na₂O content of the glass; the rate of change being greatest in the region 15 to 20 mol % Na₂O for the Na₂O-GeO₂ series and around 50 mol % in the Na₂O-P₂O₅ series. In the Na₂O-CaO-P₂O₅ glasses the covalency in the in-plane V-O δ-bond decreases andπ-bonding with vanadyl oxygen increases on substitution of CaO for Na₂O in the glass. Gradual addition of Al₂O₃ in three different Na₂O-B₂O₃ glasses did not cause any significant change in covalency either in the δ or in theπ-bonding. These changes have been discussed in terms of possible structural units in these glasses.     

A red-emitting phosphor of fully concentrated Eu-based molybdenum borate Eu2MoB2O9

The fully concentrated Eu³⁺-based molybdenum borate Eu₂MoB₂O₉ was synthesized by the solid-state reaction method. The photoluminescence excitation and emission spectra, the temperature dependent luminescence intensities and the decay curve were investigated. Photoluminescence spectra show that the phosphor can be efficiently excited by near-UV light and exhibits an intense red luminescence corresponding to the electric dipole transition ⁵D₀ → ⁷F₂ at 615 nm. The luminescence intensities and color purity were investigated by increasing the fired temperatures. The phosphor shows the stable luminescence and color purity at high temperature.     

Synthesis of magnesium borate nanorods

Single-crystalline magnesium borate Mg₂B₂O₅ nanorods have been synthesized via a simple route based on the calcinations of mixed powders containing Mg(OH)₂ and H₃BO₃. The nanorods have the typical diameters in the range of 70-120 nm and the lengths up to a few micrometers. An optimal synthesis temperature for Mg₂B₂O₅ nanorods was obtained, and the possible growth mechanism was also presented.