Photoluminescence properties of Eu2+-activated Ca2Y2Si2O9 phosphor

Eu²⁺-activated Ca₂Y₂Si₂O₉ phosphors with different Eu²⁺ concentrations have been prepared by a solid-state reaction method at high temperature and their photoluminescence (PL) properties were investigated. Photoluminescence results show that Eu²⁺-doped Ca₂Y₂Si₂O₉ can be efficiently excited by UV–visible light from 300 to 425 nm. Ca₂Y₂Si₂O₉: Eu²⁺ exhibits broad band emission in the wavelength range of 425–700 nm, due to the 4f⁶5d¹ → 4f⁷5d⁰ transition of the Eu²⁺ ions located at two different sites ((Ca/Y)1 and (Ca/Y)2) in Ca₂Y₂Si₂O₉. The effect of the Eu²⁺ concentration in Ca₂Y₂Si₂O₉ on the PL properties was investigated in detail. The results showed that the relative PL intensity reaches a maximum at 1 mol% of Eu²⁺, and a red-shift of the emission bands from these two different sites was observed with increasing Eu²⁺ concentration. Also there exists energy transfer between these two Eu²⁺ sites. The potential applications of Ca₂Y₂Si₂O₉: Eu²⁺ have been pointed out.     

Photoluminescence properties and the self-reduction process of CaAl2Si2O8:Eu phosphor

CaAl₂Si₂O₈:Eu anorthite phosphor was synthesized by the traditional solid state reaction. In the air-sintered phosphor, the Eu ions were partial self-reduced to Eu²⁺, which contributed to the observation of the blue (Eu²⁺) and the red (Eu³⁺) emission in CaAl₂Si₂O₈:Eu phosphor. To further investigate the photoluminescence properties and the self-reduction mechanism of CaAl₂Si₂O₈:Eu phosphor, the adjustment of the valence state of Eu ions by controllable approaches was studied. In addition, CaAl₂Si₂O₈:Eu phosphor shows a tunable emission from reddish to bluish region under ultraviolet excitation, which implies that it could be applied as potential phosphor for near ultraviolet light emitting diode.     

Photoluminescence properties of Eu doped Ba2ZnS3 phosphor for white light emitting diodes

The synthesis and photoluminescence properties of novel Eu²⁺ doped Ba₂ZnS₃ phosphors for white light emitting diodes (LEDs) are reported. Diffuse reflection spectra of Ba₂ZnS₃ host and synthesized phosphors have been measured. The excitation spectra of synthesized phosphors consist of three broad bands between 250 nm and 550 nm and are consistent with the diffuse reflectance spectra. The emission spectra show the characteristic 4f⁶5d¹ → 4f⁷ transition of Eu²⁺ ion and there exists efficient energy transfer from host to Eu²⁺ ions when excited by 350-nm light. The dependence of emission spectra on temperature is also measured; the possible reasons applied to explain the experimental results are also discussed. The fluorescence lifetime of Eu²⁺ in Ba_1.995ZnS₃:0.005Eu²⁺ is measured and the values are 1.49 and 23.4 μs.     

Photoluminescence properties of Ba3In2WO9: Eu3+: a novel red-emitting phosphor for WLEDs

Journal of Materials Science: Materials in Electronics - A series of new composite perovskite Ba3In2-xWO9: xEu3+ red phosphors were synthesized by high-temperature solid-state reaction. The powder...     

A promising red phosphor MgMoO4:Eu for white light emitting diodes

Motivated by the need for new red phosphors for solid-state lighting applications Eu³⁺-doped MgMoO₄ was prepared by solid-state reaction and its excitation and emission spectra were measured at room temperature. In addition, the effects of firing temperature and Eu³⁺ doping concentration on the PL intensities were also investigated. Compared with Y₂O₂S:0.05Eu³⁺, the obtained Mg_0.80MoO₄:Eu³⁺_0.20 phosphor shows a stronger excitation band near 400 nm and intensely red-emission lines at 616 nm correspond to the forced electric dipole ⁵D₀ → ⁷F₂ transitions on Eu³⁺ under 394 nm light excitation. The CIE chromaticity coordinates (x = 0.651, y = 0.348) of Mg_0.80MoO₄:Eu³⁺_0.20 close to the NTSC (National Television Standard Committee) standard values, and therefore may find application on near UV InGaN chip-based white light emitting diodes.     

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...     

红色蓄光材料Y2O2S:Eu3+的硫熔法制备及其发光性能

用硫熔法制备了系列红色蓄光材料Y2O2S ：Eux^3＋（0．01≤x≤0．10）的多晶粉末样品并系统研究了其发光特性。XRD结果表明,晶胞参数c随着Eu^3＋含量的逐渐增大而增大,而晶胞参数α没有明显的线性变化关系,这与Y2O2S ：Eu^3＋的晶体结构有关。Y2O2S ：Eux^3＋（0．01≤x≤0．10）的激发光谱相似,在626nm发射光监控下最大激发波长约在330nm附近。在330nm激发下,随着Eu^3＋含量逐渐增大,发射光谱最强发射峰位置从540nm右移至626nm,观察到红色特征发射峰626nm的强度逐渐增大,在Eu^3＋含量为0．09时,其强度达到最大。在最佳合成条件及最佳Eu^3＋含量下,正在进行掺杂Mg^2＋和Ti^4＋及其发光特性的研究。     

Dynamical processes of energy transfer in red emitting phosphor CaMoO4:Sm, Eu

Upon ⁴K_11/2 excitation of Sm³⁺ at 405 nm, the performance of energy transfer from Sm³⁺ to Eu³⁺ in the red emitting phosphor CaMoO₄:Eu³⁺, Sm³⁺ significantly extends its excitation region for better matching the near-UV LED. Photoluminescence spectra indicate that the energy transfer pathway concerns the relaxation from ⁴K_11/2 to ⁴G_5/2 of Sm³⁺ and subsequent transfer to ⁵D₀ of Eu³⁺ rather than ⁵D₁ of Eu³⁺. The fluorescent decay pattern of Sm³⁺⁴G_5/2 level in CaMoO₄:0.5% Sm³⁺, 2% Eu³⁺ is studied at 77 K based on the Inokuti-Hirayama formula, revealing an electronic dipole-dipole interaction between Sm³⁺ and Eu³⁺. The coefficient for the energy transfer is obtained to be 8.5 × 10⁻⁴⁰ s⁻¹ cm⁶. The fluorescence rise and decay pattern of Eu³⁺⁵D₀ level as Sm³⁺ is only excited at 77 K is well described by the dynamical processes of the energy transfer.     

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.     

Luminescence properties of a red phosphor europium tungsten oxide Eu2WO6

Eu₂WO₆ was synthesized by the conventional solid state reaction method. Crystal phase was characterized by the X-ray powder diffraction. The excitation and emission spectra indicate that this phosphor can be effectively excited by near UV (395 nm) and blue light (465 nm), and the emission spectra exhibit a satisfactory red performance at 611 nm, which is due to the characteristic ⁵D₀?⁷F₂ transitions of Eu³⁺ ions. The luminescence intensities and color purity were investigated by increasing the fired temperature. The phosphor shows stable luminescence and color purity at high temperature.     

Photoluminescence properties of green-emitting Eu2+-activated Ba3Si6O12N2 oxynitride phosphor for white LED applications

Eu²⁺-activated Ba₃Si₆O₁₂N₂ green-emitting phosphors were synthesized by a solid-state reaction method. X-ray diffraction patterns showed that the synthesized phosphor sintered at 1200 °C for 12 h was a Ba₃Si₆O₁₂N₂ pure phase. The synthesized phosphors were excited in UV to blue light. The emission spectra showed a broad green emission band when excited with a light at 465 nm. The highest emission intensity was observed at a Eu²⁺ concentration of 0.25 mol and the NH₄Cl concentration of the optimized flux was found to be 9 wt.%. The obtained green-emitting Ba₃Si₆O₁₂N₂:Eu²⁺ phosphors could be applied to white LED applications.     

Redox properties of a green emitting ZnGa2O4:Mn low voltage cathodoluminescent phosphor

The emission properties of ZnGa₂O₄:Mn phosphors have been compared for samples prepared via an oxalate gel route and those prepared via a conventional solid synthetic route. The firing conditions were found to be critical for obtaining good emission on account of possible redox processes involving both the Mn²⁺ activator ion and the host ZnGa₂O₄ lattice itself. An interesting reversible shift was observed for the CIE coordinates of the cathodoluminescence when the energy of the exciting electron beam was varied. This is explained by increased vibronic excitation of the ZnGa₂O₄:Mn phosphors at higher electron beam energies, resulting in a greater relative contribution of the vibronic side bands to the green emission.     

Preparation and luminescence properties of LaMgAl11O19:Eu3+ phosphor powder

LaMgAl11O19, is a kind of rare earth aluminate with the hexagonal structure, which has been used as a host material for the luminescence of various rare earth and magnet-like ions. LaMgAl11O19:Eu3+ phosphors have been prepared through the one-pot method. X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1,400 degrees C. In LaMgAl11O19:Eu3+ phosphors, the Eu3+ shows its characteristic red emission at 615 nm (5D0-7F2) upon excitation into 404 nm, with an optimum doping concentration of 15 mol% of La3+ in the host lattices.     

煅烧温度对红色长余辉发光材料Sr3Al2O6:Eu2+,Dy3+性能的影响

采用溶胶凝胶法合成了Sr3Al2O6:Eu2+,Dy3+长余辉发光材料,利用X射线衍射仪(XRD)对材料的物相进行了分析,采用荧光分光光度计、照度计测定了样品的发光特性。XRD结果表明:随着煅烧温度的升高,SrCO3杂相的衍射峰越来越弱,Sr3Al2O6相的衍射峰越来越强,1200℃时发光基质为纯的Sr3Al2O6相,1250℃时出现新的SrAl2O4杂相。激发光谱和发射光谱结果表明:长余辉发光材料的激发峰位于473nm,发射峰位于612nm,归属于Eu2+的4f65d1→4f7特征发光。温度升至1250℃时,Eu2+的发射峰为612nm和520nm,后者归属于Eu2+在发光基质SrAl2O4中的发光。综合分析得制备Sr3Al2O6:Eu2+,Dy3+发光材料合适的煅烧温度为1200℃,在此温度下,材料具有较好的初始亮度和余辉时间。     

白光LED用新型硅基氮化物红色荧光粉研究进展

综述目前白光LED用新型硅基氮化物红色荧光粉的最新研究成果和发展状况,介绍了该荧光粉在制备合成方面的最新进展,最后展望了硅基氮化物红色荧光粉的发展前景。     

BaMg2(PO4)2:Sm3+红色荧光粉发光性质的研究

采用高温固相法合成了BaNg2(PO4)2:Sm3+红色荧光材料发光材料并对其发光特性进行了研究.该荧光粉有三个主要发射峰,分别位于564 nm、600 nm、648 nm,对应于4G5/2→6H5、4G5/2→6H7、4G5/2→6H9/2的跃迁发射,其中600 nm处发射最强,呈现红色发光.随着Sm3+浓度的增加,发光强度先减小后增大,其猝灭浓度为0.01.分别掺入Li+、Na+、K+、F-、Cl-几种离子作为电荷补偿剂,均提高了样品的发光强度,其中K+是最佳的电荷补偿剂.BaMg2(PO4)2:Sm3+是一种有应用潜力的白光LED用红色荧光粉.