Luminescence and Preparation of LED Phosphor Ca8Mg(SiO4)4Cl2:Eu2+

Calcium magnesium chlorosilicate doped by europium, Ca8Mg(SiO4)4Cl2:Eu2 , was prepared by the solid state reaction at high temperature. The compound obtained is pure Ca8Mg(SiO4)4Cl2 phase with cubic structure. Its average particle size is 5 μm, and it has good dispersity and morphological form. The excitation spectrum of Ca8Mg(SiO4)4Cl2:Eu2 is a wide band, which covers from 270 to 480 nm. The emission spectrum is also a wide band peaked at 510 nm. The luminescent intensity reaches to the maximum when the concentration of Eu2 is 2%. The wavelength of emission and excitation of the phosphor with various Eu2 contents keeps constant. This spectrum range matches violet and blue LED chips very well, and its strong luminescence intensity is suitable for a green phosphor of tricolor phosphor of white light LED.     

Luminescent Properties of Green Phosphor Ca8Mg（SiO4 ）4 Cl2：EU^2＋ , DY^3＋ for LED Applications

The new phosphor calcium magnesium chlorosilicate, codoped with Eu^2＋ and Dy^3＋, was synthesized with the help of the high temperature solid state reaction in reducing atmosphere. The excitation and emission spectra were very similar to that of Ca8Mg（SiO4）4Cl2 ：Eu^2＋, and the Dy^3＋ concentration influenced the emission intensity of this phosphor. The intensity of Eu^2＋ and Dy^3＋ codoped CMSC was stronger than that of Eu^2＋ singly doped CMSC. The emission spectrum of the Dy^3＋ ion overlapped the absorption band of the Eu^2＋ ion, indicating that an energy transfer from Dy^3＋ to Eu^2＋ took place in CMSC：Eu^2＋, Dy^3＋ phosphor. The mechanism of the energy transfer from Dy^3＋ tO Eu^2＋, in this phosphor, might be resonant energy transfer.     

Intense blue-emitting Ca₂PO₄Cl:Eu²⁺ phosphor for near-ultraviolet converting white light-emitting diodes

A blue phosphor Ca2PO4Cl:Eu2+(CAP:Eu2+) was synthesized by solid state reaction.The Ca2PO4Cl:Eu2+ exhibited high quantum efficiency and excellent thermal stability.The luminescent intensity of Ca2PO4Cl:Eu2+ was found to be 128% under excitation at 380 nm,149% under 400 nm,and 247% under 420 nm as high as that of BaMgAl10O17:Eu2+.The optimal doping concentration was observed to 11 mol.% of CAP:Eu2+.The energy transfer between Eu2+ ions in CAP were occurred via electric multipolar interaction,and the critical transfer distance was estimated to be 1.26 nm.A mixture of blue-emitting Ca2PO4Cl:Eu2+,green-emitting(Ba,Sr)2SiO4:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors were selected in conjunction with 400 nm chip to fabricate white LED devices.The average color-rendering index Ra and correlated color temperature(Tc) of the white LEDs were found to be 93.4 and 4590 K,respectively.The results indicated that it was a promising candidate as a blue-emitting phosphor for the near-UV white light-emitting diodes.     

Spectral Properties and Sensitization of Ce3+ and Eu2+ Codoped Calcium Zinc Chlorosilicate

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Ba1-xSrxMgSiO4:Eu2+,Mn2+: A novel tunable single-matrix tricolor phosphor for W-LED

The Ba1-xSrxMgSiO4:Eu2+,Mn2+ phosphors were prepared by solid-state reaction. Their photoluminescence properties were inves-tigated with fluorescence spectrum and CIE chromaticity. The emission color of Eu2+ in Ba0.98-xSrxMgSiO4:0.02Eu2+ could be tuned from green to blue by adjusting the content of Sr2+. The blue emission of Eu2+ overlapped well with the excitation spectra of Mn2+, leading to an ef-ficient energy transfer from Eu2+ to Mn2+ in Ba0.98-xSrxMg1-ySiO4:0.02Eu2+,yMn2+. Ba0.93Sr0.03Mg1-ySiO4:0.02Eu2+,yMn2+ could emit three ef-ficient broad bands at 440, 530 and 640 nm. The emission color of Ba0.93Sr0.03Mg1-ySiO4:0.02Eu2+,yMn2+ could be tuned from greenish blue to yellowish white by increasing the content of Mn2+ from 0 to 0.1. By changing the content of Sr2+/Mn2+, white-light with different hues could be conveniently obtained in the Ba1-xSrxMgSiO4:Eu2+,Mn2+ phosphors. The results showed that Ba1-xSrxMgSiO4:Eu2+,Mn2+ is a promising single-phased tricolor phosphor in the fabrication of W-LED.     

Study on Ca8Mg(SiO4)4Cl2:Eu2+ Doped with Sr2+

Ca8Mg(SiO4)4Cl2:Eu2 phosphor doped with Sr2 cation for Ca2 partially, was synthesized by solid-state reaction at high temperature under reducing atmosphere, and its luminescent properties were investigated. The experimental results indicate that the emission intensity of the phosphor increases after being doped with a few amount of Sr2 ion. The emission peak of the phosphor blue shift to about 464 nm when the phosphor is doped with large quantity of Sr2 ions. The excitation spectrum indicates that the phosphor can be well excited by UV and blue light from 300 to 460 nm, and the phosphor was fitted well for the excitation by UV or blue-LED.     

Synthesis and Luminescence Properties of Red Phosphors:Mn2+ Doped MgSiO3 and Mg2SiO4 Prepared by Sol-Gel Method

Sol-gel method was utilized to synthesize two different series of red silicate phosphors:MgSiO3 and Mg2SiO4 powder samples doped with Mn2 , conducted the investigation of red long-lasting phosphor: MgSiO3:Eu2 , Dy3 , Mn2 . TGA curves of the gel precursor for two series depicted that the loss of residual organic groups and NO3 groups occurs below 450 ℃. According to the XRD patterns, the major diffraction peaks of the MgSiO3 and Mg2SiO4 series are consistent with a proto-enstatite structure (JCPDS No.11-0273) and a forsterite structure (JCPDS No.85-1364) respectively. With the excitation at 415 nm, the red emission band of Mn2 ions is peaked at 661 nm for MgSiO3:1%(atom fraction) Mn2 or 644 nm for Mg2SiO4:1%(atom fraction) Mn2 . Compared with Mg2SiO4:Mn2 samples, MgSiO3:Mn2 samples exhibit higher luminescence intensity and higher quenching concentration. In addition, the two series co-doped with Eu2 , Dy3 , Mn2 were also prepared. Photo-luminescence and afterglow properties of the two co-doped series were analyzed, which show that MgSiO3:Eu2 , Dy3 , Mn2 is more suitable for a red long-lasting phosphor.     

Luminescent properties of Ca2SiO4:Eu3+ red phosphor for trichromatic white light emitting diodes

The luminescent properties of Eu3 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 Eu3 . 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 ef- fects of the Eu3 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 Eu3 ions was 0.3 mol–1, and Li ions gave the best improvement to enhance the emission intensity. Ca2SiO4:Eu3 , Li was thus suitable for low-cost trichromatic white light emitting diodes (WLED) based on UV InGaN chip.     

Synthesis and characterization of Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+) nanorods via a solvothermal routine

Y2O2S:Eu3+,Mg2+,Ti4+ nanorods were prepared by a solvothermal procedure.Rod-like Y(OH)3 was firstly synthesized by hydrothermal method to serve as the precursor.Y2O2S:Eu3+,Mg2+,Ti4+ powders were obtained by calcinating the precursor at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ phosphor with diameters of 30-50 nm and lengths up to 200-400 nm inherited the rod-like shape from the precursor after calcined at CS2 atmosphere.The Y2O2S:Eu3+,Mg2+,Ti4+ nanorods showed hexagonal pure phase,good dispersion and exhibite...     

Effects of Eu3+ and Dy3+ doping or co-doping on optical and structural properties of BaB2Si2O8 phosphor for white LED applications

A series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2O8 phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission from Eu3+. The f-f transitions involving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3+ to Dy3+, which enhanced the emissions of Dy3+. Combinations of the emissions from Eu3+ and Dy3+ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be adjustable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3+ to Dy3+ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from Ga N-based LED chips. This presented the Ba B2Si2O8 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of Ba B2Si2O8 phosphor were also discussed in this study.     

Photoluminescent properties of Sr2SiO4:Eu3+ and Sr2SiO4:Eu2+ phosphors prepared by solid-state reaction method

Eu2+ and (or) Eu3+ doped Sr2SiO4 phosphors particles were synthesized by a conventional solid-state reaction technique, and their structural and optical properties were investigated. The X-ray diffraction (XRD) results showed that the obtained phosphors were composed of orthorhombic α'-Sr2SiO4 and monoclinic β-Sr2SiO4 phase. When excited under 256 nm, Sr2SiO4:Eu3+ phosphors showed intense emission in the red region. Sr2SiO4:Eu3+ phosphors exhibited white emissions (x=0.30, y=0.40, TC=6500 K) ranging from 425 to 650 nm when it was excited by near-ultraviolet (near-UV) light, indicating that Sr2SiO4:Eu2+ was a good light-conversion phosphor candidate for near-UV chip.     

Single-phase full-color Ba_3Lu_2（SiO_4）_3：Eu~（2＋） phosphor for white-light emitting diodes

we developed a new silicate-based full-color phosphor Ba3Lu2(SiO4)3:Eu2+ through solid state reaction.The host crystal structure was isostructural with Ca3Y2(SiO4)3 instead of garnet-type.The phosphor absorbed near-ultraviolet light from 250 to 400 nm,which was very suitable for a color converter of white LED that used UV-LED as the primary light source.The photoluminescence peak wavelength of Ba3Lu2(SiO4)3:Eu2+ was about 461 nm and a shoulder peak was around 522 nm,which resulted from the 5d-4f transition ...     

Study on Luminescence Properties and Crystal-Lattice Environment of Eu~(2 ) in Sr_(4-x)Mg_x Si_3O_8Cl_4∶Eu~(2 ) Phosphor

ChlorosilicatecrystalmaterialM4 Si3O8Cl4 (M =Ba ,Sr ,Ca)isasuitablehostlatticeforluminescencematerials .Adivalenteuropiumactivatedstrontiumchlorosilicatephosphorisakindofgoodblue greenemissionphotoluminescencematerialunderUVexcita tion .Itsluminescencepropertiesandcrystalstructurehavebeenintensivelystudied[1～4 ] .Inthechlorosili catehost ,theluminescenceofEu2 consistsofa4f6 5d1- 4f7(8S7/2 )broad bandemission ,whichbe longstoelectric dipoleallowedtransitionandhasthepropertiesoflargeabso…     

Preparation and luminescence properties of the red-emitting phosphor（Sr1-xCax）2Si5N8：Eu^2＋ with different Sr/Ca ratios

A series of Eu2+-doped ternary nitride phosphors, with a formula of (Sr1-xCax)2Si5N8: Eu2+, were synthesized by high-temperature solid-state method. The structure and luminescence properties were characterized, indicating the potential application as a red phosphor in the phosphor-converted white light-emitting diodes. The X-ray diffraction patterns showed that the Sr2Si5N8 and Ca2Si5N8 phases were generated at each end of (Sr1-xCax)2Si5N8: Eu2+ and coexisted in the range of 0.5≤x≤0.75. The emission spectra showed broad emission bands originating from the 4f65d1→4f7 transition of Eu2+ ions. The emission peak changed with the variations in Ca2+ concentration.     

A novel red phosphor:Ca2GeO4:Eu3+

A novel red phosphor Ca2GeO4:Eu3+ was prepared by the traditional solid state reaction. X-ray powder diffraction (XRD) analysis suggested that there was no impurity phase. The study on the diffusion reflection spectra of the undoped and Eu3+ doped Ca2GeO4 phosphors revealed an absorption band superposed of that of the host material and the Eu3+ ions. And the excitation spectrum presented a dominating broad band at 250–300 nm which was attributed to both the host material absorption and the charge transfer band (CTB) of the Eu3+ ions. The investigation on the excitation and diffusion spectra showed that there was an effective energy transfer from the host material to the Eu3+ ions. This was favorable to the red emission of the phosphor. Photoluminescence measurements indicated that the phosphor presents bright red emission at 611 nm under UV excitation. In addition, the Al3+ or Li+ codoping enhanced the red emission from Ca2GeO4:Eu3+ by about 3 and 2 times respectively under UV excitation.     

Photoluminescent properties of Ca2RE8(SiO4)6O2:A (RE=Y, Gd; A=Pb2+, Mn2+) phosphor films prepared by sol-gel process

Ca2RE8(SiO4)6O2:A (RE=Y, Gd; A=Pb2 , Mn2 ) phosphor films were dip-coated on quartz glass substrates through the sol-gel process. X-ray diffraction (XRD), photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. Under short wavelength UV excitation, the film showed a red emission with medium intensity. The decay curve of Mn2 luminescence in Ca2Gd8(SiO4)6O2:Pb Mn film could be fitted into a single exponential function. The lifetime of Mn2 was 10.21 ms in Ca2Gd8(SiO4)6O2.     

Luminescent Properties of Ca2 Y8 ( SiO4 ) 6O2:Eu3 + Phosphors Prepared by Spray Pyrolysis Process

Using CaCO3, metal oxides (all dissolved by nitric acid) and tetraethoxysilane Si (OC2H5 )4 (TEOS) as the main starting materials, Ca2Y8 (SiO4 )6O2: Eu3 phosphors were synthesized by spray pyrolysis.X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting phosphors.The results of XRD indicated that the 1000 ℃ annealed powders crystallize with the silicate oxyapatite structure.SEM study revealed that the phosphors consist of spherical particles with an average size of about 1 ～ 3 μm.In the crystalline Ca2 Y8 (SiO4)6O2: Eu3 phosphor, the Eu3 shows its characteristic emission corresponding to 5 D0 - 7 FJ ( J = 0, 1,2, 3, 4) transitions, with 5D0 - 7 F2 red emission (613 nm) as the most prominent group, agreeing well with the structure of the host material.     

Eu3+激活的Li2Gd4（MoO4）7钼酸盐红色荧光体及其发光性质

由高温固相反应首次合成Li2(Gd1-xEux)4(MoO4)7(0相似文献   

Photoluminescent properties of Ca2Gd8(SiO4)6O2: Dy3+ phosphor films prepared by sol-gel process

There are growing interests on phosphor thin films owing to their potential application in high-resolution devices such as cathode ray tubes and flat panel display devices. The solution-based sol-gel method is one of the most important techniques for the synthesis of vari-ous functional coating films. Compounds with the apatite structure are very suitable host lattices for various luminescent ions. Ca2RE8(SiO4)6O2 ( RE=Y, Gd, La ) is a kind of ternary rare-earth-metal silicate with oxyapatite structure, which has been used as host mate-rial for the luminescence of various rare earth and mercury-like ions. In this article, Ca2Gd8(SiO4)6O2:Dy3 phosphor films were dip-coated on quartz glass substrates through the sol-gel process. X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectra, as well as lifetimes were used to characterize the resulting films. AFM study revealed that the phosphor films consisted of homoge-neous particles. The Dy3 showed its characteristic emission in crystalline phosphor films, i.e., 4F9/2–6H15/2 and 4F9/2–6H13/2.     

SrAl_2O_4:Eu~(2+),Dy~(3+)的发光性质及机理

研究了Eu2＋、Dy3＋共激活的SrAl2O4体系的发光性能和能量传输。结果表明，Dy3＋、Eu2＋共存时，Eu2＋的发光强度远远大于无Dy3＋时的发光强度，证明Dy3＋对Eu2＋的发光有敏化作用。Dy→Eu2＋能量传输的方式为籍助于载流子的能量输运。