PDP用红色荧光粉的研究进展

简要介绍了目前研究和使用的PDP用红色荧光粉的研究现状,综述了国内外PDP用红色荧光粉的合成研究进展,最后展望了PDP用红色荧光粉的发展前景.     

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.     

等离子体显示用铝酸盐绿色荧光粉的制备及其发光性能研究

采用高温固相法合成了一系列的BaAl12O19:Mn绿色荧光粉,分析了还原气氛、Mn掺杂量、烧结温度和焙烧保温时间等因素对等离子体显示(PDP)用绿色荧光粉BaAl12O19:Mn的晶体结构、相态和发光性能的影响.结果表明,在N2、H2(H2=10%)还原气氛下烧制的样品发光强度比其在碳粉还原气氛下烧制的样品发光强度要大.当Mn掺杂比例为0.14(mol/mol),烧结温度为1350℃和保温时间为3.5h时,所制备的绿色荧光粉发光性能最佳.     

BaxAl12O19:Mnz荧光粉X射线衍射分析

研究了Ba2 、Mn2 含量对钡铝酸盐绿色荧光粉基质晶体结构的影响.XRD研究结果表明,随着Ba2 浓度的增加,存在BaAl13.2O20.8→BaAl12O19→BaAl9.2O14.8的基质结构转化,晶胞尺寸增大.BaMnAl10O17结构是贫钡铝酸盐中Mn2 的主要存在形式,其数量与Mn2 掺杂量有关.     

彩色PDP用蓝色荧光粉体的纳米化工艺研究

介绍了一种彩色PDP用蓝色荧光粉体的纳米化工艺，通过此方法，可以制备出比传统的PDP蓝色荧光粉体发光效率更高的纳米级蓝色荧光粉体，同时有效的降低了制备过程的烧结温度。制备的蓝色荧光粉体完全适用于PDP显示设备中。另外，纳米化的小颗粒也为进一步的表面包覆以防止衰减奠定了基础。     

彩色PDP纳米荧光粉的研究

等离子体显示(PDP)具有超薄、高清晰、大画面等优点而被世界公认是实现壁挂式高清晰度电视(HDTV)的首选技术,而荧光粉对PDP性能起着决定性作用.着重介绍了纳米PDP荧光粉的制备方法及影响发光性能的关键因素,并提出了其研究的技术前景.     

PDP用蓝色荧光粉的研究进展

综述了近年来等离子体平板显示器(PDP)用蓝色荧光粉的研究进展,介绍了PDP蓝色荧光粉的种类和制备方法,分析了现有PDP蓝色荧光粉存在的问题和不足,并展望了PDP蓝色荧光粉未来的发展趋势。     

K2MnAl11O19六铝酸盐催化剂的制备及其催化甲烷燃烧性能的研究

采用共沉淀法、溶胶-凝胶法和反相微乳液法制备六铝酸盐催化剂K2MnAl11O19,利用XRD、BET和TG-DTA技术及甲烷燃烧活性对催化剂进行了表征和活性验证。结果表明,3种方法所制备催化剂经1200℃焙烧4h后均可以形成完整的六铝酸盐晶型,同时都具有高的催化性能和高温稳定性,其中反相微乳液法制备的K2MnAl11O19催化剂具有较高的比表面积和甲烷催化燃烧活性,起燃温度T10%=458℃,至676℃(T90%)甲烷完全转化。     

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。     

沉淀工艺对合成BaAl12O19:Mn2+绿色荧光粉性能的影响

用化学共沉淀法制备出BaAl12O19:Mn2+绿色荧光粉,并研究了沉淀工艺参数对该荧光粉性能的影响.结果表明,通过严格控制pH值等共沉淀条件,可以获得Al3+、Ba2+、Mg2+、Mn2+离子的完全沉淀,并使其中的Al3+以结晶碳酸铝铵形式沉淀,沉淀产物经1200℃×1h煅烧后得到松软超细粉体;调节料液中Mg的掺杂量,制备出单相BaAl12O19:Mn2+荧光粉;料液滴加速度,陈化时间对荧光粉的颗粒大小和形貌有很大影响,通过试验给出了最佳滴加速度及陈化时间范围;该荧光粉的发光性能与商用荧光粉相当,粒度可控制在1～2μm.     

GeO2 dopant induced enhancement of red emission in CaAl12O19:Mn phosphor

In order to search efficient red-emitting phosphors for white LEDs application, CaAl₁₂O₁₉:Mn⁴⁺ phosphors have been prepared by a combustion method assisted with GeO₂ flux. The influence of GeO₂ concentration and annealing temperature on the structure and luminescence intensity for the phosphors has been investigated. The mechanism for luminescence enhancement has been discussed. At GeO₂ doping concentration of 1.5 mol%, the red emission intensity increases by 81% under 330 nm UVA excitation. More isolated luminescence center Mn⁴⁺ ions rather than pairs of Mn⁴⁺-Mn²⁺ ions are formed in the lattice with the introduction of GeO₂ at high temperature oxidation, leading to the enhancement of the red emission. A feasible new way to enhance the red emission in CaAl₁₂O₁₉:Mn⁴⁺ phosphor is obtained.     

Growth of BaAl2O4, SrAl12O19 & Mg2Ga4GeO10 crystals in molten bismuth germanate glasses

Small, well-formed BaAl₂O₄ blades (up to 0.5 mm), SrAl₁₂O₁₉ platelets (up to 0.01 mm), and Mg₂GeO₁₀ plates (up to 0.25 mm) can be precipitated at 1370, 1230, and 1300°C respectively from molten MO/Bi₂O₃/2 GeO₂ mixtures that contain either Al₂O₃ or Ga₂O₃. Similar experiments with PbO and CdO containing melts yielded only Al₂O₃ crystals. After quenching, all of these crystals can be separated from the adhering glass by appropriate dissolution techniques. Density, refraction, and infrared results confirm these findings.     

A simple synthesis route for high quality BaFe12O19 magnets

The present investigation reports the detailed analysis of the influence of B₂O₃-doping on magnetic and structural properties of hexagonal barium ferrites (BaFe₁₂O₁₉) synthesized via conventional ceramic technique. The results show that crystalline structure of barium ferrite is improved with small amounts of B₂O₃ between 0.1 and 1.0 wt%. Single phase particles has been obtained by 1.0 wt% B₂O₃-doping with calcination at temperatures as low as 850 °C and a range of boron concentration and calcination temperature has been extended in order to find the best synthesis conditions. Optimal properties have been achieved by 0.2 wt% of B₂O₃-doping and calcination at 1000 °C. The remanence and the saturation magnetizations increase considerably by about 40% in magnitude with B₂O₃.     

Magnetic properties of BaFe12O19 smallparticles

The magnetic properties of small BaFe₁₂O₁₉ particles about 50 nm in size have been studied; the emphasis was on small-size effects. The compound formation of the hexagonal structure was made at a relatively low temperature; the small particle size made this result possible. As compared to the bulk value, a significantly reduced saturation magnetization is observed for these particles; this agrees with similar reports made earlier by several authors. To examine these phenomena further, Mossbauer spectra were obtained with high magnetic field applied longitudinally (H_ex=16.4 and 50 kOe). The spectra show the presence of recalcitrant spins where the spin configuration has a noncollinear arrangement that even a 50-kOe magnetic field does not remove. This hard-to-saturate component may lie in the surface layer of the Ba-ferrite small particles. The data also provide evidence that the Fe ions in the bipyramidal (2b) sites undergo magnetic-field-induced oscillations at 4.2 K     

Solvent-free synthesis of hexagonal barium ferrite (BaFe12O19) particles

M-type barium ferrite (BaFe₁₂O₁₉) particles, from a mixture of barium nitrate, ferric nitrate, cetyltrimethylammonium bromide (CTAB), and ammonium carbonate, have been successfully prepared through simple grinding and calcination in the absence of any solvent. The products are characterized by X-ray diffraction, scanning electron microscope, and vibrating sample magnetometer, whose results indicate that they have well crystalline phase of BaFe₁₂O₁₉, typically hexagonal platelet-like structure, large saturation magnetization, even submicrometer particle size under the optimum condition. Meanwhile, the effects of Fe/Ba ratio, CTAB, and ammonium carbonate are also investigated. It has been found that the proper Fe/Ba ratio could suppress the intermediate phase such as α-Fe₂O₃ and BaFe₂O₄, CTAB could promote the crystallinity of BaFe₁₂O₁₉ and produce hexagonal crystal structure, and ammonium carbonate was the key for forming BaFe₁₂O₁₉ phase. This facile method may be helpful for the preparation of other multicomponent functional materials.     

Persistent luminescence of Eu and Dy doped barium aluminate (BaAl2O4:Eu,Dy) materials

Polycrystalline Eu²⁺ and Dy³⁺ doped barium aluminate materials, BaAl₂O₄:Eu²⁺,Dy³⁺, were prepared with solid state reactions at temperatures between 700 and 1500 °C. The influence of the thermal treatments on the stability, homogeneity and structure as well as to the UV-excited and persistent luminescence of the materials was investigated by X-ray powder diffraction, SEM imaging and infrared spectroscopies as well as by steady state luminescence spectroscopy and persistent luminescence decay curves, respectively. The IR spectra of the materials prepared at 250, 700, and 1500 °C follow the formation of BaAl₂O₄ composition whereas the X-ray powder diffraction of compounds revealed how the hexagonal structure was obtained. The morphology of the materials at high temperatures indicated important aggregation due to sintering. The luminescence decay of the quite narrow Eu²⁺ band at ca. 500 nm shows the presence of persistent luminescence after UV irradiation. The dopant (Eu²⁺) and co-dopant (Dy³⁺) concentrations affect the crystallinity and luminescence properties of the materials.     

Structural and morphological characterization of flux grown YTa7O19, Nd:YTa7O19, Nd:LaTa7O19 and NdTa7O19 crystals

YTa₇O₁₉ (YHT), Nd:YTa₇O₁₉ (Nd:YHT), Nd:LaTa₇O₁₉ (Nd:LHT) and NdTa₇O₁₉ (NHT) single crystals have been grown by spontaneous nucleation from high-temperature solutions using K₂Mo₃O₁₀-B₂O₃ as a flux and structurally characterized by X-ray diffraction techniques. The effect of the flux composition on the crystal morphology is discussed. The distribution of the Nd³⁺ ions in doped crystals has been investigated by electron microprobe analysis, evidencing non-uniform segregation coefficients. The Raman spectra of the investigated compounds are presented, and a reinterpretation of the fine structure present in the optical spectra is proposed in the light of the crystallographic information.     

纳米Fe3O4及Fe3O4-SrFe12O19吸波复合材料的制备及性能

采用共沉淀法成功制备出具有超顺磁性的纳米Fe₃O₄, 并将Fe₃O₄与SrFe₁₂O₁₉复合制成复合吸波材料Fe₃O₄-SrFe₁₂O₁₉, 利用X射线衍射仪(XRD)、透射电镜(TEM)、振动样品磁强计(VSM)和矢量网络分析仪(PNA)对产物的物相、显微结构、磁性能和吸波性能进行了表征与分析。结果表明, 当Fe₃O₄与SrFe₁₂O₁₉质量比为1∶0.3时, Fe₃O₄-SrFe₁₂O₁₉饱和磁化强度为11.1 emu·g^-1, 矫顽力0.86 Oe, 剩余磁化强度0.08 emu·g^-1, 其吸波性能最佳, 最大吸收峰值为-17.7 dB,-5 dB频宽为1.3 GHz, 较Fe₃O₄和 SrFe₁₂O₁₉的最大吸收峰值分别提高247%和185%, 频带分别拓宽1.12 GHz和0.40 GHz。     

Thermochemical studies on SrFe12O19(s)

The citrate-nitrate gel combustion route was used to prepare SrFe₁₂O₁₉(s) powder sample and the compound was characterized by X-ray diffraction analysis. A solid-state electrochemical cell of the type: (−)Pt, O₂(g)/{CaO(s) + CaF₂(s)}//CaF₂(s)//{SrFe₁₂O₁₉(s) + SrF₂(s) + Fe₂O₃(s)}/O₂(g), Pt(+) was used for the measurement of emf as a function of temperature from 984 to 1151 K. The standard molar Gibbs energy of formation of SrFe₁₂O₁₉(s) was calculated as a function of temperature from the emf data and is given by: (SrFe₁₂O₁₉, s, T)/kJ mol⁻¹ (±1.3) = −5453.5 + 1.5267 × (T/K). Standard molar heat capacity of SrFe₁₂O₁₉(s) was determined in two different temperature ranges 130-325 K and 310-820 K using a heat flux type differential scanning calorimeter (DSC). A heat capacity anomaly was observed at 732 K, which has been attributed to the magnetic order-disorder transition from ferrimagnetic state to paramagnetic state. The standard molar enthalpy of formation, (298.15 K) and the standard molar entropy, (298.15 K) of SrFe₁₂O₁₉(s) were calculated by second law method and the values are −5545.2 kJ mol⁻¹ and 633.1 J K⁻¹ mol⁻¹, respectively.