Preparation and photoluminescence properties of MgNb2O6:Eu3+, Bi3+ red-emitting phosphor

Rare earth Eu³⁺-doped MgNb₂O₆ red-emitting phosphor was prepared by solid-state reaction. Structure and photoluminescence properties of the samples were characterized by X-ray diffraction (XRD), scan electron microscopy (SEM) and fluorescence spectrophotometer. Meanwhile, the effect of the co-activator Bi³⁺ on the PL of the MgNb₂O₆:Eu³⁺ phosphor was studied. The results showed that the pure phase of MgNb₂O₆ could be available after firing at 1200 °C. The Mg_1?x Nb₂O₆:Eu _x ³⁺ phosphors could be effectively excited by the UV irradiation (273 nm) and emit red light at 615 nm due to the forced electric dipole ⁵ D ₀ → ⁷ F ₂ transitions on Eu³⁺, which indicated that Eu³⁺ occupied the non-inversion symmetry sites in the MgNb₂O₆ host lattice. So, the addition of the co-activator Bi³⁺ not only increased the excitation band of the MgNb₂O₆:Eu³⁺ phosphor at about 330 nm, but also strengthened the PL intensity at 615 nm. Therefore, MgNb₂O₆:Eu³⁺, Bi³⁺ might find application to InGaN chip-based white light emitting diodes.     

Enhanced photoluminescence properties of BaAl2O4: Ce3+/Li+ yellow phosphors

Journal of Materials Science: Materials in Electronics - Ce3+/Li+-activated barium aluminate phosphor (BAO) was synthesized by conventional solid-state reaction method. The crystal structure of the...     

白光LED用BaMgAl_(10)O_(17):Eu~(2+)Mn~(2+)蓝绿荧光粉

采用高温固相法制备出一种Eu2+,Mn2+共掺的蓝绿色荧光粉BaMgAl10O17:Eu2+,Mn2+(BAM:Eu2+,Mn2+),对其进行了X射线衍射分析和光谱特性的测试.研究表明,它的发射光谱为双峰结构,峰值分别位于455 nm和525 nm处.455 nm发射峰归结为BAM中部分取代Ba2+离子的Eu2+离子的5d→4f的跃迁辐射;525 nm的发射峰源于部分Eu2+能量传递给Mn2+离子,Mn2+的4T1→6A1的跃迁辐射.采用近紫外LED芯片与该荧光粉以及一种红色荧光粉Ca(La0.5Eu0.5)4Si3O13封装,在20 mA前向电流驱动下,获得了显色指数为88的白光LED.     

A novel green emitting phosphor SrAl2B2O7:Tb3+

SrAl₂B₂O₇:Tb³⁺ phosphors were fabricated by the sol–gel method. The phosphor showed prominent luminescence in green due to the ⁵D₄–⁷F₅ transition of Tb³⁺_. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis. Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 541 nm under UV excitation. It is shown that the 11% of doping concentration of Tb³⁺ ions in SrAl₂B₂O₇:Tb³⁺ phosphors is optimum.     

Synthesis of Ca3Sc2Si3O12:Ce3+ phosphor by hydrothermal Si alkoxide gelation

Single-phase Ca₃Sc₂Si₃O₁₂:Ce³⁺ green emission phosphor was synthesized by the hydrothermal silicon alkoxide gelation method. Such specimens demonstrated higher emission intensity than the Ca₃Sc₂Si₃O₁₂:Ce³⁺ samples that are prepared by conventional solid-state reaction method. It was also demonstrated that annealing in the presence of graphite as an oxygen scavenger significantly improves the fluorescence properties of this material.     

Preparation and photoluminescence properties of CaSc2O4:Eu3+ red phosphor for white LEDs

Journal of Materials Science: Materials in Electronics - The development of red phosphors has a significant impact on high-quality white LEDs lighting. In this research, the luminous properties of...     

掺杂浓度对Al2O3:Ce3+薄膜发光性能的影响

应用中频反应磁控溅射技术在载玻片上制备掺铈的Al2O3薄膜,在固定的电源功率下,氩气流量为43ml/min,氧流量为10ml/min,室温下溅射时间为90min的条件下,通过控制薄膜中的Ce3 离子的掺杂量来改变薄膜的发光性能.通过X光能量散射谱(EDS)和光致发光测量,得到发光强度和发光峰位对薄膜中的Ce3 浓度有强烈的依赖关系,并且分析了产生这种关系的原因;对发光激发谱分析表明,薄膜发光是源于薄膜中形成的氯化铈集合体中的Ce3 .Al2O3:Ce3 发光膜可应用于需要蓝光发射的平板显示领域.     

Preparation and photoluminescence properties of three-dimensionally ordered macroporous ZrO2:Eu3+

Three-dimensionally ordered macroporous (3DOM) ZrO2:Eu3+ (0.5%, 1%, 2% and 5%) were successfully prepared using a polystyrene (PS) colloidal crystal template in combination with a sol-gel method. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction (XRD), Field emission scanning electron micrograph (FESEM), N2 adsorption, and photoluminescence (PL) spectra. The results indicated that the closely packed material exhibited three-dimensional ordering of pores and a strong red (5)D0-->(7)F2 transitions under charge transfer excitation. Strong PL and abundant porosity are of particular interest and give this multifunctional material future potential.     

Use of LiF flux in the preparation of Ca3Sc2Si3O12:Ce3+ phosphor by sol-combustion method

LiF flux was added when prepare Ca₃Sc₂Si₃O₁₂:Ce³⁺ phosphors with sol-combustion method using urea as a fuel and chelating agent. Investigation of phase, morphology and photoluminescence of the phosphors reveals that this kind of method can decrease the phase-forming temperature by 400–500 °C and the phosphors show more uniform morphology and more excellent photoluminescence properties compared to conventional solid-state method. As one of the most important parameters for phosphors used in white light emitting diodes, the thermal quenching properties of the prepared samples are compared and discussed. The fabrication of single-color light emitting diodes show the Ca₃Sc₂Si₃O₁₂:Ce³⁺ phosphor prepared by sol-combustion method with LiF flux can be considered as a more promising high efficiency candidate used for white light emitting diodes than the phosphor made by solid-state method.     

Luminescence properties and energy transfer investigations of Ce3+/Tb3+ co-doped BaY2Si3O10 phosphor

A novel phosphor BaY₂Si₃O₁₀ (BYSO): Ce³⁺, Tb³⁺ was synthesized by the conventional solid-state reaction, which displays tunable color emission from blue to blue-green under ultraviolet excitation by adjusting the radio of Ce³⁺ and Tb³⁺ appropriately. Photoluminescence characteristics were carefully investigated. We demonstrate the existence of efficient energy transfer from Ce³⁺ to Tb³⁺ in BaY₂Si₃O₁₀: Ce³⁺, Tb³⁺ phosphor. The energy transfer Ce³⁺ → Tb³⁺ was proved to be governed by dipole–quadrupole interaction.     

Color-tunable emission and energy transfer studies in GdOBr:Ce3+ Dy3+ phosphor

Color-tunable blue to bluish white-emitting Ce³⁺/Dy³⁺ co-doped GdOBr phosphors have been synthesized by the conventional solid-state method. The phase structures, luminescent properties and energy transfer process were discussed in detail. Broad-band absorption originating from the f-d transition of Ce³⁺ can be found for the as-prepared GdOBr:Ce³⁺,Dy³⁺ phosphor, and color-tunable blue to bluish white emission can be realized owing to the energy transfer between Ce³⁺ and Dy³⁺. The energy transfer mechanism is demonstrated to be the dipole–dipole process. The energy transfer efficiency increases with increasing Dy³⁺ concentrations. The results indicate that Ce³⁺/Dy³⁺-activated GdOBr phosphors may be potential for phosphor-converted white-light UV-LEDs.     

Green photoluminescence of Tb3+ and Ce3+ doped mullite nanoparticles

Mullite have been actively surveyed, but as luminescent host materials, lanthanide doped mullite receive little attention. In this work, terbium and cerium co-doped mullite nanoparticles have been synthesized by co-precipitation process. These as-prepared mullite nanocrystals were characterized by transmission electron microscopy. The results showed that these nanoparticles are roughly spherical in shape and vary in size from 30 to 45 nm. The phase structures of these nanoparticles were investigated by X-ray diffraction. The results indicated that these nanoparticles crystallized well, and the peak positions and intensities agree well with the data for bulk mullite. Their fluorescence properties have been explored in detail and the resulting Al₆Si₂O₁₃: 8%Tb,0.1%Ce nanoparticles showed the typical emission bands centered at 490, 542 and 590 nm.     

Enhancement of photoluminescence properties of CaAl2Si2O8:Eu2+ by SiO2 addition

SiO₂ added phosphors, CaAl₂Si₂O₈:Eu²⁺ + xSiO₂ (x = 0, 1, 2, 3, 4, 5, 6 and 13 mol) were synthesized by a novel liquid phase precursor (LPP) method. The photoluminescence properties of phosphor added by 5 mol of SiO₂ showed 110% enhancement in the emission intensity compared to the CaAl₂Si₂O₈:Eu²⁺ phosphor. A broad emission and excitation wavelength was observed approximately from 400 nm to 600 nm centered at 430 nm and from 280 nm to 400 nm centered at 365 nm, respectively. Photoluminescence intensity of the phosphors increased continuously by SiO₂ addition up to x = 5 mol and then it decreased with further addition of SiO₂. The observed photoluminescence properties of the phosphors were discussed related to their crystalline structure and morphology.     

Zn4B6O13:Eu3+的合成与光致发光

用高温固相扩散方法首次合成了由Eu^3 离子激活的ZnB6O12红色光致发光材料，用XRD分析了样品结构，结果表明：Zn4B6O13:Eu^3 为立方晶系，晶胞参数α＝0.7471nm,V=0.4170nm^3,研究了Eu3 在Zn4B6O13中的强激发带位于394nm，主要发射峰位于610nm归属Eu^3 离子的5D0→7F2电偶极跃迁发射，根据发射光谱计算色坐标为x=0.281,y=0.619，SEM摄取了样品的清晰晶体外貌，平均颗粒度为15um左右，加入一定量助溶剂使发射光谱的相对发射强度增加了2．32－3．86倍。     

Concentration quenching of Eu2+ in SrO · 6Al2O3 : Eu2+ phosphor

In SrO · 6Al₂O₃ : Eu²⁺ phosphor, blue Eu²⁺ luminescence is observed from Eu²⁺ on the strontium site present in the lattice. The concentration quenching process between Eu²⁺ ions is determined and the corresponding concentration quenching mechanism is verified as dipole-dipole interaction. The value of the critical transfer distance is calculated as 25 Å and its reliability is confirmed by using Dexter's theory on energy transfer.     

Fabrication of SiO2@ZrO2@Y2O3:Eu3+ core-multi-shell structured phosphor

ZrO2 interface was designed to block the reaction between SiO2 and Y2O3 in SiO2@Y2O3:Eu coreshell structure phosphor. SiO2@ZrO2@Y2O3:Eu core-multi-shell phosphors were successfully synthesized by combing an LBL method with a Sol-gel process. Based on electron microscopy, X-ray diffraction, and spectroscopy experiments, compelling evidence for the formation of the Y2O3:Eu outer shell on ZrO2 were presented. The presence of ZrO2 layer on SiO2 core can block the reaction of SiO2 core and Y2O3 shell effectively. By this kind of structure, the reaction temperature of the SiO2 core and Y2O3 shell in the SiO2@Y2O3:Eu core-shell structure phosphor can be increased about 200-300 degrees C and the luminescent intensity of this structure phosphor can be improved obviously. Under the excitation of ultraviolet (254 nm), the Eu3+ ion mainly shows its characteristic red (611 nm, 5D0-7F2) emissions in the core-multi-shell particles from Y2O3:Eu3+ shells. The emission intensity of Eu3+ ions can be tuned by the annealing temperatures, the number of coating times, and the thickness of ZrO2 interface, respectively.