YVO_4:Eu~(3+),Al~(3+)荧光粉的制备及荧光性能研究

用高温固相法制备了Al3+掺杂的YVO4:Eu3+荧光粉。采用X射线粉末衍射(XRD)、环境扫描电镜(SEM)、荧光光谱(FL)等对样品进行了表征。分析了Al3+掺杂对YVO4:Eu样品晶体结构、晶胞参数和荧光性能的影响,并探讨了烧结温度对光谱性能的影响。研究结果表明:当Eu3+的浓度x(摩尔百分比)为4%,Al3+的浓度为1.5%时,在1100℃下烧结的样品其荧光性能最好,5D0→7F2处的发光强度约为未掺Al3+的2.5倍。由于Eu3+的7F2→5L6跃迁吸收,YVO4:Eu3+,Al3+荧光粉可在395 nm被有效激发。因此,YVO4:Eu3+,Al3+可以作为近紫外激发的白光LED红色荧光粉。     

Design and Synthesis of Tb~(3+)-doped KGW Crystal for the Exploration of Scintillation Performance with X-ray Imaging

X-ray scintillators have been widely used in many fields owing to their strong penetrating ability,including security inspection, medical imaging, nuclear cameras, high energy physics and so forth. To explore new scintillation materials, we designed and synthesized KGW:Tb bulk scintillation crystals with monoclinic phase structure. We explored the fluorescence performance of KGW:Tb by testing the photoluminescence spectrum and fluorescence decay curve and observed strong green light emission in the visible light range at room temperature.Moreover, our crystal has a high stability under X-ray irradiation, a good sensitivity response and an appreciable light output(3424 ph/MeV) that is approximately twenty times more than PbWO_4. Moreover, we used a 0.98 mm thickness polished crystal sheet for X-ray imaging applications and observed excellent results. Therefore, KGW:Tb crystal may be an important direction for X-ray scintillation detection.     

NaCa1-x-y Bay PO4:Eux3+红色荧光粉的合成及发光性质研究

采用高温固相法制备了可被近紫外光有效激发的NaCa1-x-yBayPO4:Eux3+(0.00≤x≤1.00)荧光粉.分别探讨了不同Eu3+掺杂量对NaCaPO4:Eu3+、NaBaPO4:Eu3+荧光粉发光强度的影响,以及改变Ca2+、Ba2+浓度对NaCa0.94-xBaxPO4:Eu3+0.06(x=0.1、0....     

Sm~(3+)掺杂(Y,Tb)AG:Ce~(3+)荧光粉的制备及光谱性能

采用柠檬酸溶胶凝胶燃烧合成法制备了一系列组成的(Y,Tb)3Al5O12:Ce3+,Sm3+荧光粉。通过X射线衍射、荧光光谱研究了不同Sm3+离子共掺杂浓度下(Y,Tb)AG:Ce3+荧光粉的晶体结构及光致发光性能。Rietveld全图拟合(Rietveld method of wholepattern fitting)结果表明:掺杂后样品仍为纯立方石榴石相,随着Sm3+离子共掺杂浓度的增加,样品的晶胞参数增大。在467 nm激发下,激发能由Ce3+离子向Sm3+离子单向传递,从而在617nm处出现红光发射。Tb3+离子取代不利于Ce3+离子与Sm3+离子的能量传递,同时Ce3+离子受更强的晶体场作用及与O2-离子间增强的共价性使发射主峰红移,Sm3+掺杂的TAG:Ce体系中,激发能由敏化剂Ce3+离子向激活剂Sm3+离子的传递路径包括5d→4f2F5/2,7/2(Ce3+)和7F6→5D4(Tb3+)到4G5/2→6H7/2(Sm3+)两部分。     

Spectral Characteristics of LiSrBO3：Tb^3＋ Green Phosphor

LiSrBO3:Tb3+ green phosphor was synthesized by means of a solid state reaction and its spectral characteristics were studied. The emission spectrum of LiSrBO3:Tb3+ consists of four major bands at 486, 544, 595 and 620 nm under the excitation of near ultraviolet irradiation, which are originated from the 5D4→7F6, 5D4→7F5, 5D4→7F4 and 5D4→7F3 characteristic transitions of Tb3+, respectively. Monitored at 544 nm, the excitation spectrum of the phosphor extends from 220 nm to 390 nm, with the excitation peaks c...     

Tb~(3+):LaBr_3能级分析

本文对Ln~(3+):LaCl_3和Ln~(3+):LaBr_3体系进行晶场能级分析,其主要目的有二:(一)对已测得的实验能级进行理论计算和归宿;(二)探讨能级间的相互作用及等价算符方法和不可约张量方法对该体系的适合程度。理论计算采用投影算符方法构成J=6,5,4,3,2,1,0的D_(3h)不可约表示基矢。在整个计算过程中,晶场矩阵由相同不可约表示的基矢构成。对~7F(J=6,5,4,3,2,1,0)本文分别应用等价算符方法(略去晶场J相互作用即略去所谓的晶场J混合作用)和不可约张量方法(考虑晶     

铽-铕共掺杂的硅酸铝钠荧光体的光致发光性能及能量传递

采用温和的固相反应法合成了具有四方相结构的铽一铕共掺杂的硅酸铝钠(NaAlSiO_4:Tb~(3+),Eu~(3+))发光材料.利用粉末X射线衍射(XRD)、荧光光谱(PL)、时间分辨光谱(TRPL)以及荧光寿命等手段对合成的样品进行表征.研究结果表明:通过改变NaAlSiO_4:Tb~(3+),Eu~(3+)中Eu~(3+)离子的掺杂浓度,可实现其绿光及红光发射的调控;由于Tb~(3+),Eu~(3+)离子间的有效能量传递,Tb~(3+)离子的共掺杂可显著增强该基质中Eu~(3+)离子的发光性能;该能量传递现象可由TRPL光谱等手段进行证实,根据荧光寿命的数值计算可知,从Tb3~(3+)向Eu~(3+)离子的能量传递效率高达95%.     

Fe~(3+)掺杂的TiO_2纳米复合粒子的合成及表征

利用酸催化的溶胶-凝胶法合成了一系列不同Fe~(3+)掺杂量的TiO_2纳米复合 料子。用XRD,TEM,UV-vis等技术进行了表征。结果表明：在所研究的掺杂量范围 内(x_B = 0.0005 ～0.1000),未发现有铁氧化物的晶相生成;Fe~(3+)的掺杂可以 实现TiO_2由锐钛矿(anatase)结构向金红石(rutile)结构的低温转化,随着Fe~ (3+)掺杂量的增大,对光的吸收发生红移,吸收强度增大。掺杂适量的Fe~(3+)可 以使TiO_2纳米微粒的光催化活性得以提高。     

稀土光化学Tb~3在KlO_4-KOH体系中的光氧化

本文报道在KIO_4-KOH碱性溶液中Tb~(3+)生成可溶性络合物的光氧化.研究了碱度,络合剂浓度,Tb~(3+)浓度,辐照面积,光强和辐照时间等因素对了b~(4+)生成的影响.KOH浓度应大于0.3M,KIO_4的浓度应比Tb~(3+)的初始浓度大两个数量级.生成的Tb~(3+)可溶性络离子呈棕红色.最大吸收峰420nm附近,比较稳定.     

Eu~(3+)-doped LaPO_4 and LaAlO_3 nanosystems and their luminescence properties

Eu3+ ion-doped LaPO4 nanowires or nanorods have been successfully synthesized by a simple hydrothermal method.The influence of varying the hydrothermal and subsequent sintering conditions on the morphology and structure of the LaPO4 host has been investigated by scanning electron microscopy(SEM) and X-ray diffraction(XRD).For comparison,the Eu3+ ions were also doped into monoclinic monazite LaPO4 nanoparticles and perovskite LaAlO3 nanoparticles.The relative intensities of the emission lines of the LaPO4:Eu...     

Color-tunable Upconversion Properties of Tb~(3+)/Er~(3+)/Yb~(3+) Tri-doped Na_5Gd(WO_4)_4 Crystals

In this work, novel phosphors Na5Gd(WO4)4: Tb^3+/Yb^3+ and Na5Gd(WO4)4: Tb^3+/Er^3+/Yb^3+ phosphors were synthesized by the solid state reaction method. The photoluminescence properties were investigated. The introduction of Er^3+ to NGW: Tb^3+/Yb^3+ was used to modify the chromaticity coordinates, then providing a good color tunable property. The change in the chromaticity coordinates induces the shift of emission color from yellow-green to blue-green for NGW: Tb^3+/Er^3+/Yb^3+ as the temperature increases. All the results indicate that the NGW: Er^3+/Tb^3+/Yb^3+ phosphors may be used as optical temperature sensing materials.     

Unusual Luminescence of Ca8[Al12O24]（WO4）2： Tb^3＋

The luminescence properties of aluminate sodalite Ca8[Al12024](WO4)2 (CAW) undoped and doped with Th^3 are reported and discussed. At room temperature the emission of tetrahedral WO4^2- in CAW showed an abnormally small Stokes shift (9060 cm^-1), which is related to the crystal structure of CAW. A strong absorption band in the excitation spectrum of the Th^3 -activated CAW is ascribed to the absorption of the charge transfer state Th^4 -W^5 , into which the excitation resulted in the efficient emission from the ^5D4 level of Tb^3 , but not from the ^5D3 level.     

LaOX：Dy^3＋体系荧光光谱的理论解析

用改进的卤化法合成了LaOX:Dy~(3+)磷光体(X=Cl,Br),测定了它们在室温和液氮温度下的荧光光谱;基于DSCPCF模型的计算结果,对Dy~(3+)离子在该系列基质中的~4F_(9/2)→~6H_J(J=15/2,13/2,11/2)发射及~6H_(15/2)→~4G_(11/2)、~4I_(15/2)激发带进行了理论归属,理论能级与实测光谱吻合。     

Spectroscopic investigations of Nd(3+)-doped alkali chloroborophosphate glasses

Optical absorption spectra were studied in wavelength region 400-900 nm for the Nd(3+)-doped alkali (R = Li, Na and K) chloroborophosphate glasses at room temperature. The energy level scheme of the 4f(3) electron configuration was deduced from the observed energy level data using a parametrized Hamiltonian (H(F1)) model which includes 20 free-ion interaction parameters. Reasonable correlation was obtained between the experimental and calculated energy levels. The Judd-Ofelt model for the intensity analysis of induced electric dipole transitions has been applied to the measured oscillator strengths of the absorption bands to determine the three phenomenological intensity parameters Omega(2), Omega(4) and Omega(6) for each glass. Using these parameters, the total radiative transition rates (A(T)), non-radiative relaxation rates (W(NR)), branching ratios (beta(R)), integrated cross-sections for the stimulated emission (Sigma), excited state emission intensities (f(ESE)) and excited state absorption intensities (f(ESA)) have been theoretically calculated for certain excited Nd(3+) fluorescent levels. From the results obtained, the conclusion is made about the possibility of using these glasses as laser media.     

Preparation and Spectroscopic Properties of Pr~(3+)-doped Transparent Glass-ceramic Containing LiYF_4 Nanocrystals

Pr~(3+)-doped transparent oxyfluoride glass-ceramic containing tetragonal LiYF_4 nanocrystals has been synthesized by melting-quenching method and subsequent thermal treatment and spectroscopic properties of Pr~(3+) ions were investigated. The crystalline phase and microstructure of the LiYF_4 nanocrystals were studied by X-ray diffraction(XRD) and transmission electron microscopy(TEM), respectively. Compared with those of Pr~(3+)-doped glass(Pr~(3+):PG), the sharp absorption and emission bands of Pr~(3+)-doped glass-ceramic(Pr~(3+):GC) reveal parts of Pr~(3+) ions are incorporated into LiYF_4 nanocrystals. The peak absorption cross-section at 443 nm(~3H_4 → ~3P_2) adds to 110% and the full width at half maximum(FWHM) for the band around 443 nm reduces from 22 to 14 nm after crystallization. The fluorescence lifetime of the ~3P_0 multiplet of Pr~(3+) ions increases from 5.35 to 11.14 μs after crystallization. The results indicate that this glass-ceramic is promising to be a visible laser material.     

新型全色发光材料NaCaPO_4:Dy~(3+)制备及发光性能

釆用高温固相法制备了NaCaPO4∶Dy3+系列样品,并在紫外(UV)及真空紫外(VUV)区域研究了系列样品的发光性能.紫外激发光谱显示在350nm处有最强的激发峰,可以有效地吸收紫外光并将其转化为可见光.真空紫外激发光谱表明,NaCaPO4∶Dy3+能有效地吸收无汞荧光灯的激发源并将其转化为可见光.系列样品发光均呈现为白色,这种材料有潜力作为全色显示材料应用于发光二极管(LED)和无汞荧光灯中.     

Up-conversion Properties of Er~(3+)/Yb~(3+) Co-doped Li_3Ba_2Gd_3(MoO_4)_8 Phosphors

Er~(3+)/Yb~(3+)co-doped Li_3Ba_2Gd_3(Mo O_4)_8 phosphors were synthesized by conventional solid state reaction method,and their structure and spectral properties were investigated.The diffuse reflectance spectra showed that the ~4I_(15/2)→~4I_(11/2) transition of Er~(3+)and the ~2F_(7/2)→~2F_(5/2)transition of Yb~(3+)ions were highly overlapped.Under the excitation of 980 nm,three up-conversion(UC)luminescence bands around 530,555 and 660 nm were observed,corresponding to the~2H_(11/2)→~4I_(15/2),~4S_(3/2)→~4I_(15/2) and ~4F_(9/2)→~4I_(15/2) transitions of Er~(3+)ions,respectively.The effects of the concentration and pumping power on the UC intensities of Li_3Ba_2Gd_3(Mo O_4)_8:Er~(3+)/Yb~(3+)phosphors were investigated,and the possible UC mechanism was proposed based on the results.     

微波等离子体法合成SrAl_2O_4:Eu~(2+),Dy~(3+)中激活剂的浓度猝灭研究

采用微波等离子体法合成SrAl_2O_4:Eu~(2+),Dy~(3+)长余辉发光材料,通过对掺杂不同激活剂浓度的产物的光谱性能、余辉性能、相组成结构的分析以及晶胞常数的计算,探讨了微波等离子体法合成srAl_2O_4:Eu~(2+),Dy~(3+)时,激活剂Eu~(2+)的浓度猝灭特性.XRD测试结果表明,Eu~(2+)离子的掺入对基质晶格畸变影响很小;光谱和余辉性能测试表明Eu~(2+)的掺杂浓度对产物的瞬时发光强度影响较大,相对而言对余辉性能的影响程度不大.产物的发光性能随Eu~(2+)摩尔浓度的增大呈现先增强后减弱的趋势,发光中心Eu~(2+)离子的猝灭浓度为4%.结合EDX结果说明,与高温固相法以及其他一些方法相比,采用微波等离子体合成技术可在一定程度上提高Eu~(2+)离子的临界猝灭浓度,从而为进一步提高长余辉发光材料的发光性能提供了可能.     

Impact of surface coating on morphological,optical and photoluminescence properties of YF_3:Tb~(3+) nanoparticles

A simple polyol and sol–gel Stober process were employed for synthesis of YF_3:Tb~+(core), YF_3:Tb~+@LaF_3(core/shell) and YF_3:Tb~+@LaF_3@SiO_2(core/shell/SiO_2) nanoparticles(NPs). The phase purity, crystalinity,morphology, optical and photoluminescence properties were investigated and discussed with the help of various analytical techniques including X-ray diffraction pattern,FE-transmission electron microscopy(TEM),FTIR, UV/vis absorption, energy band gap and emission spectra. XRD andFE-TEM studies indicate the formation of core/shell nanostructure and ~10 nm thick amorphous silica surface coating surrounding the core-NPs, which is also confirmed byFTIR spectral results. The surface modifications of core-NPs significantly affect the optical features in the form of energy band gap, which were correlated with particle size of the nanomaterials. The comparative emission spectral results show that after inert layer coating the luminescent core-NPs display stronger emission intensity in respect to core and silica coated core/shell/SiO_2-NPs. The solubility character along with colloidal stability was improved after silica surface modification, whereas luminescent intensity was suppressed causing the surface functionalized with high energy silanol(Si-OH) molecules. These novel luminescent nanomaterials with enhanced emission intensity and excellent solubility in aqueous solvents would be potentially useful for fluorescence bioimaging/optical bio-probe etc.     

铕(Ⅲ)激活的磷酸镧发光性质研究

LaPO₄:Eu³⁺的发射光谱包含较强的Eu³⁺⁵D_o→⁷F₁跃迁发射和较弱的⁶D₁→⁷F₁跃迁发射。主发射峰583nm,对应于Eu³⁺5D_o→⁷F₁跃迁.通过对Eu³⁺的两种跃迁发射强度及荧光寿命和Eu³⁺浓度关系的测定和理论分析,探讨了发光中心Eu³⁺离子同的交叉弛豫和能量迁移机理。