BaAl12O19中Mn2+和Tb3+的发光及Tb3+对Mn2+的能量传递

采用溶胶-凝胶法合成了Mn2+、Tb3+单掺及共掺的BaAl12O19荧光粉,对其发光性质和Tb3+对Mn2+的能量传递机理进行了研究.研究结果表明,Tb3+单掺的BaAl12O19荧光粉,发射峰位于440nm、489nm、543nm、587nm和623nm,属于Tb3+的5D3→7FJ和5D4→7FJ (J=6,5,4,3)跃迁发射;Mn2+单掺的荧光粉,发射峰位于516nm,归属于Mn2+的4T1→6A1跃迁发射.Mn2+,Tb3+共掺后,Mn2+的发射强度明显提高,而Tb3+的发光强度降低,Tb3+对Mn2+有能量传递作用.初步证实Tb3+对Mn2+的能量传递机理为激子能量传递.     

硼磷酸钇基质中Ce3+、Tb3+、Gd3+的发光及能量传递

用 BPO4 和稀土氧化物为原料 ,首次合成了铈、铽、钆共激活的硼磷酸钇绿色荧光粉 ,研究了基质中Ce3 、Tb3 、Gd3 的发光以及它们之间的相互作用。该基质中存在 Ce3 → Tb3 、Gd3 → Tb3 的能量传递 ,以及 Ce3 和 Gd3 之间的竞争吸收和独自发射。在铈、铽共激活的硼磷酸钇体系中掺入钆后 ,Ce3 的发射以及 Tb3 的 5D4 → 7FJ和 5D3→ 7FJ的发射均增强 ,但总的效果是 Gd3 阻碍了 Ce3 → Tb3 的能量传递。基质中钇全部被钆代替后 ,荧光粉的发光亮度增加 ,光纯度也较好 ,发光色坐标 X值稍变小。     

Na_2WO_4:Eu~(3+),Tb~(3+)光致发光材料的发光性质和能量传递

利用溶胶-凝胶法,将激活离子Eu~(3+)和Tb~(3+)以单一或混合的形式掺入体系得到了光致发光材料.分别研究了材料中激活离子Eu~(3+)和Tb~(3+)的含量及其离子之间的能量传递关系.主要利用材料的三维荧光光谱,激发光谱和发射光谱对其的发光性质进行了分析;结果发现,材料中有两个发光中心,分别为Eu~(3+)和Tb~(3+),在不同的波长光的激发下得到的材料的红绿色发光强度不同,而且Eu~(3+)和Tb~(3+)的掺杂浓度比对发光色度影响很大.所以可以根据选择最适合的Eu~(3+)和Tb~(3+)的浓度比来控制材料的发光色,也可以通过不同的激发波长对材料的色度进行微调.     

Eu2＋ and Dy3＋ codoped （Ca,Sr）7（SiO3）6Cl2 highly efficient yellow phosphor

Eu2+ and Dy3+ codoped(Ca,Sr)7(SiO3)6Cl2 yellow phosphors were successfully synthesized by self-flux method. The structure, morphology and photoluminescence properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM) and photoluminescence spectra. The as-prepared phosphor showed a broad emission spectrum centered at 550 nm for Eu2+single-doped phosphor, while located at 548–544 nm for the Eu2+, Dy3+ codoped samples under excitation at 380 nm light. The emission intensity was greatly improved when Dy3+ was doped into the(Ca,Sr)7(SiO3)6Cl2:Eu2+ system. The composition-optimized sample with 3 mol.% of Dy3+ and constant 10 mol.% of Eu2+ exhibited a 220% PL enhancement compared to the phosphor with 10 mol.% Eu2+ single-doped. Meanwhile, it was found that the quantum efficiency of phosphor namely(Ca,Sr)7(SiO3)6Cl2:3 mol.% Dy3+, 10 mol.% Eu2+ could get up to 24.6%. The synthesized yellow-emitting(Ca,Sr)7(SiO3)6Cl2:Dy3+,Eu2+ is a promising candidate as high-efficiency yellow phosphor for NUV-excited white LEDs.     

Synthesis of Long Afterglow Phosphors MAI204：Eu^2＋ , Dy^3＋ （M=Ca, Sr, Ba） by Microemulsion Method and Their Luminescent Properties

Long afterglow phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4：Eu^2＋, Dy^3＋ and SrAl2O4 ： Eu^2＋, Dy^3＋ are with monoelinie crystal structure and phosphor BaAl2O4：Eu^2＋ , Dy^3＋ is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4： Eu^2 ＋ , Dy^3＋ （M = Ca,Sr, Ba） indicates that the luminescent materials can he excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） is found mainly at λem of 440 nm （M = Ca）, 520 nm （M = Sr） and 496 nm （M = Ba） respectively, the corresponding colors of emission light are blue, green and eyna-green respectively. The afterglow decay tendency of phosphors can he summarized as three processes： initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I = At^ - n, and the sequence of afterglow intensity and time is Sr 〉 Ca 〉 Ba.     

Combustion synthesis and upconversion luminescence of CaSc_2O_4：Yb~（3＋）,Er~（3＋） nanopowders

Novel up-conversion (UC) luminescent nano-powders, CaSc2O4:Yb3+:Er3+ were prepared with a combustion method at an ignition temperature as low as 200 oC. The CaSc2O4:Yb3+,Er3+ nano-powder had an orthorhombic CaFe2O4-type structure, and showed sphere-like morphology with an average diameter of about 30 nm. It gave strong green (525, 552 nm) and red (652-674 nm) up-conversion luminescence due to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ under a 980 nm semiconductor laser excitation a...     

PMBP和DPSO协萃剂负载泡塑萃取Sc~（3＋）、Y~（3＋）、La~（3＋

本文论述了ＰＭＢＰ和ＤＰＳＯ协萃剂负载于聚醚型聚氨酯泡沫塑料上，萃取微量稀土元素钪、钇、镧、镨和钕的最佳实验条件（萃取剂浓度、温度、酸度）。研究了它们的萃取性能（萃取百分率、分配比、萃取容量），说明它是实用的萃取方法。     

Energy transfer processes from Yb3＋ to Ln3＋ （Ln=Er or Tm） in heavy metal glasses

Heavy metal glasses doubly doped with Yb3+ and Ln3+ ions(Ln=Er or Tm) were studied. Glass host matrices were limited to lead borate glass and lead germanate glass. Efficient resonant(Yb3+-Er3+) and non-resonant(Yb3+-Tm3+) energy transfer was observed for the studied systems. Near-infrared luminescence spectra at 1.53 μm(Er3+) and 1.9 μm(Tm3+) were detected under excitation of Yb3+ by 975 nm diode laser line. They corresponded to 4I13/2→4I15/2(Er3+) and 3F4→3H6(Tm3+) transitions of rare earth ions, respectively. The unusual large spectral linewidth nearly close to 110 nm for 4I13/2→4I15/2 transition of Er3+ ions in lead borate glass was obtained, whereas long-lived near-infrared luminescence at 1.53 μm was detected in lead germanate glass. Quite different situation was observed for Yb3+-Tm3+ doubly doped glasses. In contrast to lead borate glass, near-infrared(3F4→3H6) luminescence spectra were registered for Tm3+ ions in lead germanate glasses, only. These phenomena strongly depended on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy.     

Mechanism of upconversion emission enhancement in Y_3Al_5O_（12）：Er~（3＋）/Li~＋ powders

Er3+ and Li+ codoped Y3Al5O12(YAG) powders were prepared for a systematic investigation of their upconversion emissions.X-ray diffraction(XRD),upconversion emission spectra,pump power dependence,FT-IR spectra and decay time were studied to characterize the samples.With Li+ doping,the upconversion emission intensity of Er3+ doped YAG powders was obviously enhanced,accompanied with an increase in the ratio of green to red intensity.The enhancement of emission intensity could be attributed to two mechanisms:on...     

Luminescence investigation of Eu~（3＋）-Bi~（3＋） co-doped CaMoO_4 phosphor

A series of Eu³⁺-Bi³⁺ co-doped CaMoO₄ red phosphors were synthesized via the solid-sate reaction method. The crystal structures of the obtained samples were identified by X-ray powder diffraction (XRD). The photoluminescence property was investigated, and the results showed that the intensity of excitation spectra and emission spectra could be changed with different doping ratios of Bi³⁺/Eu³⁺. The proposed explanation of these changes was from the energy transfer between Bi³⁺ and Eu³⁺ and the unbalanced charge from the substitution of Eu³⁺ and Bi³⁺ for Ca²⁺ in CaMoO₄. The obtained samples are a promising red light emitting phosphor for the needs of different excitation sources with near-UV and blue GaN-based chips.     

Preparation and upconversion luminescence of YAG（Y3Al5O12）：Yb^3＋,Ho^3＋ nanocrystals

Cubic YAG: Yb3+, Ho3+ pure phase nanocrystals were synthesized by using coprecipition nitrate and ammonium hydrogen carbonate as raw materials. After calcining the precipitates at 800 ℃, the resultant YAG: Yb3+, Ho3+ nanocrystals were nearly spheric and the particle size was about 40 nm. Intense upconversion spectra were observed on the powder compact pumped by a 980 nm continuous wave diode laser, and green emission centered at 549 nm, red emission centered at 667 nm, and NIR centered at 760 nm were all due to two photons process, which originated from 5S2 (5F4)→5I8, 5F5→5I8, and 5S2 (5F4)→5I7 transitions, respectively.     

Sr_2MgSi_2O_7∶Eu,Nd体系中Eu~(2+)向Nd~(3+)的能量传递

通过高温固相法合成了Sr2MgSi2O7∶Eu2+,Nd3+发光材料,测试了样品的物相结构、可见和近红外激发和发射光谱、荧光寿命等,研究了Eu2+对Nd3+的近红外发光性能的影响及近红外发光相对强度变化的规律,考察了煅烧温度、煅烧时间对近红外发光性能的影响。结果表明,1200℃下煅烧的Sr2MgSi2O7∶0.02Eu2+,0.01Nd3+样品近红外发光强度最强,Eu2+对Nd3+的近红外发光敏化效果最好。证实了在Sr2MgSi2O7∶Nd3+,Eu2+体系中Eu2+通过无辐射传递的模式向Nd3+有效传递了能量。     

Blue-green BaAl_2O_4：Eu~（2＋）,Dy~（3＋） phosphors synthesized via combustion synthesis method assisted by microwave irradiation

Blue-green luminescent BaAl2O4:Eu2+,Dy3+ phosphor powders were synthesized via combustion synthesis method assisted by microwave irradiation in air. The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectrophotometer. The XRD results revealed that when the concentration of urea was over 3 times higher than theoretical quantities, a BaAl2O4 single hexagonal phase was obtained. The SEM results revealed that the surface of the BaAl2O4:Eu2+,Dy3+ pow...     

Photoluminescence of BaGdB9O（16）：Eu^3＋ co-doped Al^3＋ or Sc^3＋ under UV-VUV excitation

Single phase of BaGd0.9-xMxEu0.1B9O16 (M=Al or Sc, 0≤x≤0.3) powder was prepared by the solid-state reaction and its photoluminescence (PL) properties were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. Monitored with 613 nm emission, the excitation spectra of BaGd0.9-xMxEu0.1B9O16 consisted of three broad bands peaking at about 242, 208, and 142 nm, respectively. The one at about 242 nm originated from the charge transfer band (CTB) of O2-→Eu3+. The other two were assigned to the absorption of the host, which was overlapped with absorptions among borate groups, f→d transition of RE3+ (RE=Gd, Eu), and the charge transfer transition of O2-→Gd3+. The maximum emission peak was observed at about 613 nm in the emission spectra of BaGd0.9-xMxEu0.1B9O16 under both 254 and 147 nm excitation, which originated from the electric dipole 5D0→7F2 transition of Eu3+. When excited with 254 nm, the integral emission intensity of Eu3+ increased after Al3+ or Sc3+ substituting Gd3+ partly in BaGd0.9Eu0.1B9O16. Under 147 nm excitation, the integral emission intensity of Eu3+ decreased after some Gd3+ was replaced by Sc3+, but increased after adding appropriate Al3+ into BaGd0.9Eu0.1B9O16.     

Photoluminescence properties and effect of Bi~（3＋） dopant of Eu~（3＋） and Dy~（3＋） co-doped Sr_3V_2O_8

Photoluminescence properties of Sr 2.5 Dy 1/3-x Eu x V 2 O 8(x=0,0.06,0.12,0.18,0.24,0.33) were investigated.The excitation spectra included a broad band in the short wavelength region and several sharp lines in the longer wavelength region,and the spectral origin were discussed.The emission spectra were measured in two different exciting ways,i.e.,exciting the VO 4 group at 270 nm and the Eu 3+ ion at 398 nm,respectively,and the energy transferring process was reasonably suggested.Furthermore,multi-color emission could be achieved in Sr 2.5 Dy 1/3-x Eu x V 2 O 8,indicating that the studied samples had potential applications in the white light emitting diodes.Further investigation showed that reducing the concentration of Eu 3+ and Dy 3+ and introducing Bi 3+ as a sensitizer ion greatly enhanced the emission intensity.     

Energy transfer in Tb~（3＋）,Yb~（3＋） codoped Lu_2O_3 near-infrared downconversion nanophosphors

Tb3+ and Yb3+ codoped Lu2O3 nanophosphors were synthesized by the reverse-strike co-precipitation method. The obtained Lu2O3:Tb3+,Yb3+ nanophosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectra. The XRD results showed that all the prepared nanophosphors could be readily indexed to pure cubic phase of Lu2O3 and indicated good crystallinity. The Tb3+→Yb3+ energy transfer mechanisms in the UV-blue region in Lu2O3 nanophosphors were investigated. The experimental results showed that the strong visible emission around 543 nm from Tb3+ (5D4→7F5) and near-infrared (NIR) emission around 973 nm from Yb3+ (2F5/2→2F7/2) of Lu2O3:Tb3+,Yb3+ nanophosphors were observed under ultraviolet light excitation, respectively. Tb3+ could be effectively excited up to its 4f75d1 state and relaxed down to the 5D4 level, from which the energy was transferred cooperatively to two neighboring Yb3+. The Yb3+ concentration dependent luminescent properties and lifetimes of both the visible and NIR emissions were also studied. The lifetime of the visible emission decreased with the increase of Yb3+ concentration, verifying the efficient energy transfer from the Tb3+ to the Yb3+. Cooperative energy transfer (CET) from Tb3+ to Yb3+ was discussed as a possible mechanism for the near-infrared emission. When doped concentrations were 1 mol.% Tb3+ and 2 mol.% Yb3+, the intensity of NIR emission was the strongest.     

氧化钇标准物质中CeO_2，Pr_6O_（11），Dy_2O_3，PbO，NiO

氧化钇标准物质中ＣｅＯ_２，Ｐｒ_６Ｏ_（１１），Ｄｙ_２Ｏ_３，ＰｂＯ，ＮｉＯ，ＣａＯ的ＩＣＰ－ＡＥＳ测定江瑞源（福建省测试技术研究所，福州，３５０００３）高纯稀土中杂质测定有控制气氛电弧法、色层分离电弧法及ＩＣＰ－ＡＥＳ法等。而ＩＣＰ－ＡＥＳ法对高纯?..     

Synthesis and optical properties of Dy~（3＋）, Li~＋ doped CaMoO_4 phosphor

A series of CaMoO4 phosphors doped with trivalent dysprosium ions (Dy3+) and lithium (Li+) were prepared by solid state method at 750 °C for 3 h. X-ray diffraction (XRD) confirmed the crystal structure and quality of phosphors. Scanning electron microscopy (SEM) in- dicated that the phosphors presented good crystalline state, and the crystalline grain sizes were about 0.5-3.0 μm. The emission spectra showed that the phosphors had intense emission at 480 (4F9/2→6H15/2), 576 (4F9/2→6H13/2) and 660 nm (4F9/2→6...     

Up-conversion luminescence of Er~（3＋）-doped and Yb~（3＋）/Er~（3＋） co-doped 12CaO·7Al_2O_3 poly-crystals

The optical properties of Er3+-doped and Yb3+/Er3+ co-doped 12CaO·7Al2O3 (C12A7) poly-crystals, synthesized by high temperature solid state method, were investigated in detail. For Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals, two main emission bands centered around 530/550 nm (green) and 660 nm (red) were observed under 980 nm diode laser excitation via an up-conversion process. The intensity of green up-conversion emission had a strong increase in Er3+ (1.0 mol.%, 1.5 mol.%, 3.0 mol.%), and the intensity ratio of red to green up-conversion emission had an increase in Yb3+ (1.0 mol.%, 2.0 mol.%, 10. 0 mol.%)/Er3+ (fixed at 1.0 mol.%). This detailed study of the up-conversion processes allowed us to identify the dominant up-conversion mechanisms in Er3+-doped and Yb3+/Er3+ co-doped C12A7 poly-crystals.