Luminescent properties of Ca_2SiO_4:Eu^(3+) red phosphor for trichromatic white light emitting diodes

The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.

Combustion Synthesis and Luminescent Properties of CaO: Eu^(3+), M^+ (M=Li, Na, K) Phosphor

Li ^＋ , Na^ ＋ , or K ^＋ co-doped CaO： Eu^3＋ phosphors were prepared by the combustion synthesis method and characterized by X-ray diffraction （XRD）, photoluminescence and photolumi-nescence excitation （PL-PLE） spectra. The experimental results show that, upon excitation with 250 nm xenon light, the emission spectrum of the CaO： Eu^3＋ consists of 4f-4f emission transitions from the 5D0 excited level to the 7FJ （J=1, 2, 3） levels with the mainly electric dipole transition 5D0→7F2 of Eu3＋, indicating that the Eu^3＋ occupies a low symmetry. The charge-transfer band （CTB） shows somewhat red shift with the decreasing ionic radii of co-doped alkali metal ions. The PL and PLE intensities are significantly enhanced, especially the strongest intensity of luminescent is CaO： Eu^3＋, Li ＋ phosphor, when alkali metal ions are incorporated. The strongest peak of emission is slightly shifted from 614 to 593 nm, indicating that the Eu^3＋ ion locates in a symmetric position （Oh） when alkali metal ions are incorporated.

Thermally enhanced photoluminescence and temperature sensing properties of Sc2W3O12:Eu3+ phosphors

Recently, lanthanide-ion-doped luminescent materials have been extensively used as optical thermometry probes due to their fast responses, non-contact, and high sensitivity properties. Based on different responses of two emissions to temperature, the fluorescence intensity ratio(FIR) technique can be used to estimate the sensitivities for assessing the optical thermometry performances. In this study, we introduce different doping concentrations of Eu^(3+) ions into negative thermal expansion material Sc2W3O12to increase the thermal-enhanced luminescence from 373 K to 548 K, and investigate the temperature sensing properties in detail. All samples can exhibit their good luminescence behaviors thermally enhanced.The emission intensity of Sc2W3O12:6-mol% Eu3+phosphor reaches 147.8% of initial intensity at 473 K. As the Eu3+doping concentration increases, the resistance of the sample to thermal quenching decreases. The FIR technique based on each of the transitions 5D→7F_(1)(592 nm) and 5D→7F_(2)(613 nm) of Eu3+ions demonstrates a maximum relative temperature sensitivity of 3.063% K-1at 298 K for Sc_(2)W_(3)O_(12):6-mol% Eu3+phosphor. The sensitivity of sample decreases with the increase of Eu3+concentration. Benefiting from the thermal-enhanced luminescence performance and good temperature sensing properties, the Sc_(2)W_(3)O_(12):Eu^(3+)phosphors can be used as optical thermometers.

Photoluminescence properties of LaF_3:Eu^(3+) nanoparticles prepared by refluxing method

The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction（XRD）, field emission scanning electron microscopy（FE-SEM）, UV-vis diffuse reflectance spectrum, and photoluminescence spectra.The results of XRD indicated that the obtained LaF3：Eu^3＋ nanoparticles were well crystallized with a hexagonal structure.The FE-SEM image illustrated that the LaF3：Eu^3＋ nanoparticles were spherical with an average size around 30 nm.Under irradiation of UV light, the emission spectrum of LaF3：Eu^3＋ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ（J=1, 2, 3, 4） transitions of the Eu3＋ ions, with the dominating emission centered at 590 nm.In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies（-350 cm^-1） of LaF3 matrix.The optimum doping concentration for LaF3：Eu3＋ nanoparticles was determined to be 20mol.%.

Luminescence properties of YAl_3(BO_3)_4 phosphors doped with Eu^(3+) ions

YAl3 （BO3）4： Eu^3＋ phosphors were prepared by the conventional solid state reaction. The phase structure and morphology were investigated by X-ray diffraction （XRD） and scanning electron microscope （SEM）. Doping YAl3（BO3）4： Eu^3＋ phosphors with concentration of Eu^3＋ ions of 0, 2, 5, 8 and 10 mol% were studied and their luminescent properties at room temperature were discussed. The excitation spectrum of Y0.95Eu0.05Al3（BO3）4 was composed of a broad band centered at about 252 nm and a group of lines in the longer wavelength region. In the emission spectra, the peak wavelength was about 614 nm under a 252 nm UV excitation. The optimal doping concentration of Eu^3＋ ions in YAl3（BO3）4： Eu^3＋ phosphors was 8 mol%.

Synthesis and Luminescent Properties of Ce^(3+), Tb^(3+) Co-Doped Zn_4B_6O_(13)

Green-photoluminescence material Zn4B6O13: Ce3+, Tb3+ was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters: a(0) = 0.7472 nm, V = 0.4172 nm(3), and structural properties are investigated by XRD. The excitation and emission band of Ce3+ ion single-doped in Zn4B6O13 transfer longer spectra 2.38 similar to 4.94 kk than in other matrices. Emission band of Ce3+ ion better overlaps with the F-7(6)-->(5)G(2),D-5(1),H-5(7) absorption band of Tb3+. It shows that emission of Tb3+ ion is sensitized by Ce3+. In Zn4B6O13:Ce3+, Tb3+, it is due to the energy transfer mechanism, resonance transfer of electric multipolar interaction of the dipole-dipole between Ce3+-->Ce3+ and Ce3+-->Tb3+. The color coordinates of Zn4B6O13: X 0.281, gamma = 0.619. The mean diameter of the particles is 0.23 mum.

Alternating Double Trinucleate[Yb_3(μ_3-OH)_2O]_2 Chain Bridged byμ_3-OH Mode in a 3D Yb^(3+)-CP and Its Near Infrared Luminescent Properties

A new 3D coordination polymer,namely,[Yb_3（μ_3-OH）_3（μ_2-OH）（DDLA）_（2.5）（BIPY）]（1,H_2DDLA = 2,2-dipyridyl-4,4-dicarboxylic acid,BIPY = 2,2？-bipyridine）,has been synthesized via solvothermal method. The complex crystallizes in triclinic,space group P1 with a = 7.7339（4）,b = 15.6699（8）,c = 17.2221（9） ？,α = 68.8630（10）,β = 88.1890（10）,γ = 88.1740（10）°,V = 1945.27（17） ？~3,Z = 2,D_c = 2.296 g·cm^3,μ（MoKα） = 1.075 mm^（-1）,F（000） = 1268,S = 1.068,R = 0.0263 and wR = 1.067 for 5176 observed reflections with I 〉 2σ（I）. Compound 1 contains a unique alternating double trinucleate {[Yb_3（μ_3-OH）_2OH]_2}_n chain,in which Yb^（3＋） is bridged through μ_3-OH and μ_2-OH two coordination modes. The alternating double trinucleate chains are further extended into a 3D structure through DDLA^（2-） ligands by different coordination modes. The photoluminescence spectra show 1 is highly sensitized by the characteristic emission of Yb^（3＋） in the NIR region.

Effect of Al^3＋ on Photoluminescence Properties of Eu^3＋-Doped BaZr（BO3）2 Phosphors

We discuss the influence of Al^3＋ on the charge transfer state （CTS） and the photoluminescence properties of BaZr（BO3）2：Eu. The results reveal that there is a red shift which is about 20nm for the charge transfer state when doping with Al^3＋ and indicate the formation of ‘free＇ electrons due to the change of microstructures. In addition, the influence or Al^3＋ doping on the PPR is analysed and a new explanation is raised based on the photo luminescent mechanism. It is the CTS intensity rather than the CTS energy that influences the peak-peak ratio.

NaCa_(2)Mg_(2)(VO_(4))_(3)∶Eu^(3+)颜色可调荧光粉的熔盐法合成及其发光性能研究

以廉价的NaCl为熔盐,采用熔盐法合成了NaCa_(2-x)Mg_(2)(VO_(4))_(3)∶xEu^(3+)(0≤x≤0.10)系列颜色可调荧光粉,系统研究了合成条件、Eu^(3+)掺杂对样品结构及发光性能的影响。结果表明,反应温度为800℃、反应时间为0.5 h、原料与熔盐的质量比为1∶3是合成NaCa_(2)Mg_(2)(VO4)_(3)的适宜反应条件,所得样品为NaCa_(2)Mg_(2)(VO_(4))_(3)纯相,且结晶度高。样品微观形貌随着反应温度的升高由珊瑚状演变为表面光滑的不规则多面体。Eu^(3+)掺杂对NaCa_(2)Mg_(2)(VO_(4))_(3)的晶体结构影响较小,但对其发光性能影响较大。随着Eu^(3+)浓度(x)的增加,VO_(4)^(3-)的特征发射带强度逐渐减弱;而Eu^(3+)的特征发射峰强度先增大后减小,当x=0.06时,达到最大。故通过改变Eu^(3+)浓度,可对样品的发光颜色进行调制,从绿色可调制为黄绿色、黄色、黄白色、橙红色。荧光光谱与荧光寿命分析表明,NaCa_(2)Mg_(2)(VO_(4))_(3)∶Eu^(3+)体系中存在VO43-到Eu^(3+)的能量转移过程,能量转移效率约为23%;热稳定性分析结果表明,当温度从室温(298.15 K)升高到398.15 K时,NaCa_(1.94)Mg_(2)(VO_(4))_(3)∶0.06Eu^(3+)荧光粉在614 nm处的主发射峰强度可保留起始值的68.4%,表现出良好的热稳定性。

Sr_(2)InP_(3)O_(11):Eu^(3+)红色荧光粉的发光性能及占位影响

红色荧光粉是提高发光二极管(LED)显色指数、降低色温的重要组分。本文选择具有红色特征发射的Eu^(3+)作为激活剂离子,以新型磷酸盐Sr_(2)InP_(3)O_(11)为荧光粉基质,通过高温固相反应合成了系列Sr_(2-x)InP_(3)O_(11):xEu^(3+)(简化为S_(2-x)IP_(3):xEu^(3+))和Sr_(2)In_(1-x)P_(3)O_(11):xEu^(3+)(简化为S_(2)I_(1-x)P_(3):xEu^(3+))荧光粉。利用XRD、室温及变温PL光谱、量子效率和荧光寿命,详细研究了所制备荧光粉的光致发光性能及其受阳离子位点(Sr位和In位)的影响规律。研究结果表明,这两类荧光粉在254nm和393nm激发下均可发出明亮的橘红光(593nm和612nm主导)。此外,所合成的荧光粉具有较好的色稳定性和热稳定性,表明其在荧光粉转换型白光LED照明和显示领域具有一定的发展潜力。

SrLaLiTeO_(6):Dy^(3+),Eu^(3+)荧光粉的制备及发光性能研究

白光发光二极管(LED)的商业合成方案缺少红光成分,导致合成的白光色温较高、显色性差,因此开发性能优异的单相暖白光荧光粉成为白光LED领域研究的重要课题。以Dy^(3+)和Eu^(3+)为掺杂剂,SrLaLiTeO_(6)(SLLT)为基质,采用固相反应法制备了SrLaLiTeO6:Dy^(3+),Eu^(3+)无机荧光粉,并通过X射线衍射仪、荧光分光光度计和色度坐标分析荧光粉的晶体结构及光学性能。结果表明:Dy^(3+)和Eu^(3+)成功进入SLLT晶体,无杂质产生;SLLT:0.07Dy^(3+),yEu^(3+)荧光粉在351 nm激发下能够同时发射蓝、黄、红光,证明了Dy^(3+)和Eu^(3+)之间存在能量传递,弥补了单掺Dy^(3+)荧光粉缺乏红色发射的缺陷;Eu^(3+)离子最佳掺杂浓度为0.05,此时的色度坐标为(0.391 9,0.380 9),色温为3 733 K,接近暖白光区域。因此,SrLaLiTeO_(6):Dy^(3+),Eu^(3+)荧光粉是一种性能优异的暖白光LED荧光粉。

Magnetic and luminescent properties of bifunctional composite Fe_(3)O_(4)@Y_(2)O_(2)S:Eu^(3+)

As a kind of non-destructive testing method,magnetic particle inspection is widely used in the fields of aviation and high-speed rail.The properties of magnetic fluorescent bifunctional composites,such as fluorescence intensity and magnetic properties,have increasing demands in magnetic particle inspection.Rare earth compounds offer potential as novel materials for fluorescent magnetic bifunctional composites due to their excellent optical properties and extremely narrow emission spectra.In this work,the rare earth fluorescent material Y_(2)O_(2)S:Eu^(3+) was synthesized by solid-state reaction method.Fe_(3)O_(4)nanoparticles prepared by hydrothermal method were uniformly coated on the Y_(2)O_(2)S:Eu^(3+) particles through physical adsorption of surfactants.The obtained Fe_(3)O_(4)@Y_(2)O_(2)S:Eu^(3+) exhibits dark red color under the ultraviolet light.In additio n,X-ray diffractio n,morphology,photoluminescence and hyste resis loop of Fe_(3)O_(4)@Y_(2)O_(2)S:Cu^(3+) were investigated.The luminescence mechanism of Y_(2)O_(2)S:Eu^(3+) is described in detail Fe_(3)O_(4)@Y_(2)O_(2)S:Cu^(3+) displays good paramagnetism and has a good controllability under a magnetic field.The magnetic particle inspection of Fe_(3)O_(4)@Y_(2)O_(2)S:Eu^(3+) was performed using a 4-pole electromagnet and a test piece shim.The magnetic fluorescent bifunctional composite presented in this work can be applied for non-destructive testing.

新型红色荧光粉Sr_(3)CaNb_(2)O_(9):Sm^(3+),Eu^(3+)的发光特性和能量传递分析

利用高温固相反应法制备一系列单基质荧光粉Sr_(3)CaNb_(2)O_(9):xSm^(3+),yEu^(3+)(x=0.04~0.09,y=0.03~0.15),并对样品的物相形貌、发光性能、能量传递机制和CIE色坐标进行分析。研究表明,Sr_(3)CaNb_(2)O_(9):xSm^(3+)荧光粉在激发波长为407 nm时的浓度淬灭点为x=0.07。在Sr_(3)CaNb_(2)O_(9):0.07Sm^(3+),yEu^(3+)荧光粉中,随着Eu^(3+)掺杂浓度的增加,Sm^(3+)的发光强度降低而Eu^(3+)发光强度却先增加后降低,Eu^(3+)的浓度淬灭点为y=0.09。Sm^(3+)→Eu^(3+)的能量传递以电偶极-电偶极相互作用为主,能量传递效率达到76.6%。色坐标图表明Eu^(3+)离子的加入可使色坐标从橙红色区域向纯红色区域移动。此外,样品还具有较高的色纯度和较低的色温。结果表明,Sr_(3)CaNb_(2)O_(9)∶Sm^(3+),Eu^(3+)荧光粉有望成为白光LED发出红光物质的候选材料。

Luminescence Properties of Sm^(3+) doped Bi_2ZnB_2O_7

The phosphors of （Bi1- x Smx ） 2ZnB2O7 （ x = 0. 01, 0. 03, 0. 05, 0. 07, and 0. 09） were synthesized by conventional solid state reaction. The purity of all samples was checked by X-ray powder diffraction （XRD）. XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7, indicating that the Bi^3＋ in Bi2ZnB2O7 can be partly replaced by the Sm^3＋ without the change of crystal structure. The excitation and emission spectra at room temperature show the typical 4f-4f transitions of Sm^3＋ . The dominant excitation line is around 404 nm due to ^6H5/2→^4K11/2 and the emission spectrum consists of a series of lines at 563, 599, 646, and 704 nm due to ^4G5/2→^6H5/2, ^6H7/2, ^6H9/2, and ^6H11/2, respectively. The optimal concentration of Sm^3＋ in Bi2ZnB2O7 is about 3mol% （relative to lmol Bi^3＋ ） and the critical distance Rc was calculated as 2.1 nm. The temperature dependence of the emission intensity of Bi1.94Sm0.06ZnB2O7 was examined in the temperature range between 100 and 450 K. The quenching temperature where the intensity has dropped to half of the initial intensity is 280 K. The lifetime for Sm^3＋ in Bi1.94Sm0.06ZnB2O7 is fitted as a value of 0.29 and 1.03 ms.

Luminescent characteristics of Ba_3Y_2(BO_3)_4:Eu^(3+) phosphor for white LED

The Ba3Y2（BO3）4：Eu^3＋ phosphor was synthesized using a high temperature solid-state reaction method and the luminescent characteristics were investigated. The emission spectrum exhibited one strong red emission at 613 nm, corresponding to the electric dipole 5D0-TF2 transition of Eu^3＋, under 365 nm excitation. The excitation spectrum of 613 nm indicated that the Ba3Y2（BO3）n：Eu^3＋ phosphor was effectively excited by ultraviolet （UV） （254, 365 and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the 613 nm emission of the Ba3Y2（BO3）n：Eu^3＋ phosphor was measured. The results showed that the emission intensity increased with increasing Eu^3＋ concentration, and then decreased. The CIE color coordinates of Ba3Y2（BO3）4：Eu^3＋ phosphor were x=0.641 and y=0.359 at 15 mol.% Eu^3＋.

Effects of Annealing Treatments on Luminescence and Scintillation Properties of Ce:Lu_3Al_5O_(12) Crystal Grown by Czochralski Method

Lu3Al5O12 single crystals grown in pure N2 atmosphere by Czochralski method were annealed in oxidizing atmosphere （air）and reducing atmosphere （H2 ＋ N2）, respectively. Effects of annealing treatments on luminescence and scintillation properties of the crystals were investigated. The crystal annealed in air showed the highest luminescence intensity under blue light or vacuum ultraviolet excitation in comparison with that annealed in reducing flux or the as-grown crystal. Under X-ray excitation, crystal annealed in reducing atmosphere had the lowest light yield, and crystal annealed in air had the fastest decay time under ^137Cs 662 keV γ-ray excitation. Different annealing treatments resulted in different luminescence and scintillation properties, which might related with oxygen vacancies or defect existing in the crystals.

Luminescent characteristics of LiCaBO_3:Eu^(3+) phosphor for white light emitting diode

tiCaBO3：Eu^3＋ phosphor was synthesized by high solid-state reaction method, and its luminescent characteristics were investigated. The emission and excitation spectra of LiCaBO3：Eu^3＋ phosphors exhibited that the phosphors could be effectively excited by near ultraviolet （400 nm） and blue （470 nm） light, and emitted red light. The effect of Eu^3＋ concentration on the emission spectrum of LiCaBO3：Eu^3＋ phosphor was studied. The results showed that the emission intensity increased with increasing Eu^3＋ concentration, and then decreased because of concentration quenching. It reached the maximum at 3mol.% Eu^3＋, and the concentration self-quenching mechanism was the d-d interaction according to the Dexter theory. Under the conditions of charge compensator Li^＋, Na^＋ or K^＋ incorporated in LiCaBO3, the emission intensities of LiCaBO3：Eu^3＋ phosphor were enhanced.

Two Interpenetrated and Polycatenated Zn(Ⅱ)Coordination Polymers:Syntheses,Structures and Luminescent Properties

Two fascinating Zn（II）entangled coordination polymers,[Zn（eoba）(bbi)];·nH;O（1）and[Zn（boba）(bbi);];（2）,(bbi=1,1?-（1,4-butanediyl）-bis（imidazole）,H;eoba=4,4?-（ethane-1,2-diyldioxy）-dibenzoic acid,H;boba=4,4?-（butane-1,4-diyldioxy）-dibenzoic acid),were obtained by hydrothermal technology and characterized by elemental analysis,infrared spectrum,thermogravimetric analysis and single-crystal X-ray diffraction.1 is a rare 2D→3D example with a 3-fold parallel interpenetration and polycatenaned architecture.2 features a scarce2D→2D example with a 3-fold parallel interpenetrating network which possesses polyrotaxane and polycatenane characters.Moreover,the luminescent properties of 1 and 2 have been discussed.

Influence of Molten Salt on Luminescent Intensity and Particle Size of Y_2O_3:Eu^(3+) Phosphor

The Y-Eu oxalate precursor was prepared with a homogeneous precipitation method. And the additives, Na2CO3, S, NaCl or their combination, were introduced into the precursor to prepare Y2O3 ：Eu^3＋ red phosphors at 1000 1300 ℃ for 2 h. The effect of molten salts on particle size and luminescent intensity was studied. The experimental results showed that the complex molten salt （Na：CO3 ＋ S ＋ NaCl） was conductive to enhance the luminescent intensity of Y2O3 ：Eu^3＋. The emission intensity of the phosphor prepared with these additives at 1300 ℃ was about 45% higher than that of the one prepared without molten salt, and about 11% higher than that of the corresponding commercial phosphor. Meanwhile, the particle size of Y2O3 ：Eu^3＋ phosphor was controlled effectively with the molten salt.

Synthesis and Luminescence Properties of Green-emitting Phosphor CaSc_(2)O_(4):Ce^(3+)

Using CaCO_(3),Sc_(2)O_(3),and CeO_(2) as raw materials,we prepared the CaSc_(2)O_(4):Ce^(3+)green phosphors for white light LEDs via a high-temperature solid-phase method in a reducing atmosphere.X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),fluorescence spectroscopy and other means were used to characterize the phase structure,apparent morphology,and photoluminescence properties of the product.CaSc_(2)O_(4) was synthesized under a reducing atmosphere(95%N_(2)+5%H_(2))at 1400℃ for 4 hours.Upon excitation with a blue light(450 nm wavelength),CaSc_(2)O_(4):Ce^(3+)displays a broadband green emission peak at 525 nm.The color coordinates of CaSc_(2)O_(4):7%Ce^(3+)emission peak are(0.3712,0.5940),and the product morphology is 1μm granular.Hence,it acts as a green phosphor suitable for white LEDs that can be excited by blue light.