Raman spectra of RE2O3 （RE=Eu,Gd, Dy,Ho, Er,Tm, Yb,Lu, Sc and Y）：laser-excited luminescence and trace impurity analysis

Raman spectra of a series of cubic rare earth sesquioxides RE2O3 （RE=Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y） were investigated by Raman spectroscopy with both 532 and 785 nm laser lines. Abundant additional bands due to laser-excited lumines-cence were observed. For Eu2O3, Dy2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3, the luminescence mainly came from the intrinsic trivalent lanthanide ions, while for Gd2O3, Lu2O3, Sc2O3 and Y2O3, their luminescence were attributed to the trace impurities of other lumines-cent lanthanide ions such as Eu3＋, Nd3＋and Er3＋. This investigation confirmed Raman spectroscopy as a useful tool for detecting trace luminescent lanthanide impurities.     

Effect of Nb~(5+) and Cu~(2+) codoping on thermal properties of Gd_2Zr_2O_7 ceramic

In this work,Nb⁵⁺and Cu²⁺were selected to partially substitute Zr4+in Gd₂Zr₂O₇for studying the phase structure,microscopic morphology and thermal properties.Gd₂(Zr_(1-3 x/2)Nb_xCU_x/2)₂O₇(x=0,0.05,0.1,0.15,0.2,0.25)ceramic materials were synthesized by high-temperature solid-state reaction method.The results show that the Gd₂(Zr_(1-3 x/2)Nb_xCu_x/2)₂O₇ceramics present cubic pyrochlore structure with clear grain boundaries and dense cell structure.And the thermal expansion coefficient of Gd₂(Zr_(1-3 x/2)Nb_xCu_x/2)₂O₇ceramics gradually decreases because of the incorporation of Nb⁵⁺and Cu²⁺into Zr-site in Gd₂Zr₂O₇.Meanwhile,its thermal conductivity decreases firstly and then increases with the doping of Nb⁵⁺and Cu²⁺,which reaches the lowest value for the composition of Gd₂(Zr_0.85Nb_0.1Cu_0.05)₂O₇.     

Upconversion Luminescence Properties of Ho^3＋, Tm^3＋, Yb^3＋ Co-Doped Nanocrystal NaYF4 Synthesized by Hydrothermal Method

Nanocrystal of upconversion （UC） phosphor Ho^3＋, Tm^3＋ , and Yb^3＋ co-doped NaYF4 was prepared by the hydrothermal method in the presence of the complexing agent EDTA. Under 980 nm diode laser excitation, the impact of different concentrations of Ho^3＋ ion on the UC luminescence intensity was discussed. The law of luminescence intensity versus pump power shows that the 474 nm blue emission, 538 nm green emission, and 642 nm red emission are all due to the two-photon process, while the 450 nm blue emission is a three-photon process. The UC mechanism and processes were also analyzed. The sample was characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The result shows that Ho^3＋ ,Tm^3＋ , and Yb^3＋ co-doped NaYF4 prepared by the hydrothermal method exhibits a hexagonal nanocrystal.     

Luminescence properties of Tm^3＋/Yb^3＋, Er^3＋/Yb^3＋ and Ho^3＋/Yb^3＋ activated calcium tungstate

CaWO4 phosphor activated by the Tm3+/Yb3+,Er3+/Yb3+ and Ho3+/Yb3+ ions were synthesized by a traditional high-temperature solid-state method.The crystal structures and morphologies of the products were characterized by X-ray powders diffraction method(XRD) ,infrared spectra(FT-IR) and scanning electron microscopy(SEM) .The samples were found to show up-conversion luminescence properties.CaWO4 doped with Tm3+/Yb3+ showed blue luminescence characteristic of Tm(III) ion in the range of 460-485 nm,corresponding to the 1G4→3H6 electronic transition.CaWO4 doped with Er3+/Yb3+ showed strong green luminescence at 510-565 nm(2H11/2,4S3/2→4I15/2) and weak red luminescence at 640-685 nm(4F9/2→4I15/2) of Er(III) ion.CaWO4 doped with Ho3+/Yb3+ phosphor emitted green luminescence at 525-560 nm(5S2,5F4→5I8) and red luminescence at 630-670 nm(5F5→5I8) and at 730-770 nm(5S2,5F4→5I7) ,which is the characteristic of Ho(III) ion.     

Upconversion luminescence of Yb3+/Ho3+/Er3+/Tm3+ co-doped KGd(WO4)2 powders

Different lanthanide ions (Yb3+/Ho3+/Er3+/Tm3+) codoped KGd(WO4)2 phosphors were prepared by high-temperature solid-state reaction. The upconversion luminescence properties of two-ion and three-ion co-doped KGd(WO4)2 phosphors were investigated in detail. The concentration quenching effect of the two-ion co-doped KGd(WO4)2 phosphors was studied, and the optimum concentration of Ho3+, Er3+ and Tm3+ are 2 mol.%, 2 mol.% and 3 mol.%, respectively. The Yb3+/Ho3+/Tm3+ co-doped KGd(WO4)2 sample is the best white ...     

Effect of trivalent rare earth ions doping on the fluorescence properties of electron trapping materials SrS：Eu~（2＋）

Trivalent rare-earth ions (La3+,Pr3+,Nd3+,Sm3+,Gd3+,Tb3+,Dy3+,Ho3+,Er3+,Tm3+,and Yb3+) were investigated as the codoped auxiliary sensitizer for the electron trapping materials SrS:Eu2+ in order to enhance the fluorescence properties.It was found that Sm3+ and Tb3+ had the best photoluminescence stimulated luminescence (PSL) effect among the selected trivalent rare-earth ions.All the SrS:Eu2+ samples doped by different trivalent rare-earth ions could be stimulated by 980 nm laser after being exposed to the conventional sunlight,and they emitted PSL with the peak located at 615 nm.The result also indicated that some co-doped rare earth ions could increase fluorescence intensities of the traditional electron trapping materials SrS:Eu2+.     

Tunable electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_x)_2Si_2O_7:Ce scintillator by adjusting La/Gd ratio

Mixed crystal strategy is an effective approach of improving the luminescence properties of optical materials and has been adopted widely in many systems.In this paper,the La-mixed Gd_2 Si_2 O_7:Ce polycrystalline samples were successfully synthesized by a sol-gel method.The crystal structure and luminescence properties were confirmed and discussed by XRD,UV-Vis luminescence spectra,and XEL,respectively.The vacuum ultraviolet excitation spectra and thermoluminescence glow curves were also systematically investigated and discussed at varied temperature.A combination of the first-principles calculations and optical characterization experiments was employed to study the electronic band structure of host material,revealing that the band gap is narrowed and the 5 d_1 level of Ce~(3+) shifts to higher energy as the La content increases.The luminescence the rmo-stability and activation energy were also measured and calculated.It indicates that thermo-stability is strongly dependent on the La concentration.An effective approach is developed to tune the electronic band structure,luminescence properties and thermostability of(Gd_(1-x)La_x)_2 Si_2 O_7:Ce scintillator by adjusting La/Gd ratio.     

Analysis of Response Surface in the Study of RE(NO_3)_3-HNO_3-P507-Kerosene Extraction System

RE(NO_3)_3-HNO_3-P507-kerosene extraction system(RE=La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Y)was studied by the response surface technique.14 models for extracting single rare earth ele-ment in a broad range of acidity and initial rare earth concentration were obtained by using the stepwiseregression method.Three-dimensional display of the response surface of the model of extracting Er~(3 )wasshowed as an example,which reveals clearly the dependence of distribution ratio upon both initial acidity and ini-tial rare earth concentration.     

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.     

Synthesis and luminescent properties of lanthanide-doped ScVO_4 microcrystals

High quality and monodispersed ScVO_4 microcrystals were successfully synthesized via a mild hydrothermal route using NH_4VO_3 as vanadium source. The X-ray power diffraction(XRD) and field-emission scanning electron microscopy(FE-SEM) results indicated that the size, shape, and phase formation of the ScVO_4 microcrystals could be tuned by altering the reaction temperature, reaction time, and p H value of the initial solution. Furthermore, the down- and upconversion luminescence of ScVO_4:Ln(Ln=Eu, Dy, Sm, Yb/Ho, Yb/Er, and Yb/Tm) microcrystals were characterized and the respective energy transfer processes were also discussed. The experimental results demonstrated that reactions at 200 oC, 24 h, and pH=6 could generate perfect ScVO_4 microcrystals, which were then used for luminescence studies.     

镧铁合金中14项稀土杂质含量的测定—电感耦合等离子体发射光谱法

采用电感耦合等离子体发射光谱法（ICP-OES）测定镧铁合金中铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇稀土杂质元素。镧铁合金试料在硝酸介质中,以近似基体匹配法校正基体对测定的影响,直接以氩等离子体光源激发,用标准曲线法进行光谱测定。为选择合适的分析线,先根据光谱波长表预选几条强度大,激发电位低的谱线,然后对此谱线进行轮廓扫描,从而选出一条背景平坦,信背比大,基体及共存元素干扰少或无干扰的谱线作为分析线。用基体匹配法配制标准溶液,根据产品标准XB/T 407—2020指标,以铁（85 %）与镧（15 %）配制成混合基体,配制6个系列标准溶液进行曲线绘制。该方法适用于铈、镨、钕、钐、铕、钆、铽、镝、钬、铒、铥、镱、镥、钇含量在0.005 %~0.25 %的分析测定。方法的相对标准偏差（n=11）在0.74 %~2.58 %之间,用标准加入法对方法的回收率进行试验,测得回收率在91.75 %与107.75 %之间, 能满足产品测定要求。      

Structure and Luminescent Enhancement Effect of Na_5Eu(MoO_4)_4 by Doping(WO_4)~(2-)

The luminescent enhancement effect of Na_5Eu(MoO_4)_4 by doping(WO_4)~(2-) has been studied.When the value x in Na_5Eu(Mo_(1-x)W_xO_4)_4 is in 0相似文献   

电感耦合等离子体原子发射光谱法测定镝铁电解粉尘中15种稀土元素

用硝酸和氢氟酸溶解试样,高氯酸冒烟除氟,在硝酸介质中用电感耦合等离子体原子发射光谱法(ICP-AES)测定了镝铁电解粉尘中La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y 15种稀土元素。为了提高高含量元素的测定准确度,在测定基体元素Dy时,采用铟作内标;为了消除基体效应对稀土杂质元素测定的影响,采用基体匹配的校准曲线。镝铁电解粉尘中铁含量很低(铁的质量分数不超过1%),对测定没有影响。实验方法测定了一镝铁电解粉尘样品,结果表明,La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Ho、Er、Tm、Yb、Lu和Y 14个稀土杂质元素测定值与ICP-MS的测定值基本一致,镝和14个稀土元素的合量与重量法测得的稀土总量吻合。     

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.     

Yb3+，Er3+掺杂Y2Ti2O7荧光粉的制备与上转换发光机理研究

采用溶胶-凝胶法制备合成了(Y_0.98-xYb_xEr_0.02)₂Ti₂O₇(x=0, 0.02, 0.04...0.10)荧光粉, 分别采用XRD和荧光光谱仪对样品的结构和上转换发光性能进行了表征.研究了Yb3+掺杂浓度对样品上转换发光性能的影响, 并对样品的发光机理进行了研究.结果表明, 所得样品为面心立方结构的烧绿石相.在980nm激发下, 样品展现出很强的上转换荧光发射并且发光颜色可以通过Yb3+掺杂浓度来调节.样品上转换绿光和红光发射均为双光子过程并且交叉弛豫过程在上转换红光发射过程中占据主导作用.      

Structure and luminescence properties of Sm~(3+) doped Y_2MoO_6 phosphor under near ultraviolet light excitation

A series of Sm~(3+) doped Y_2MoO_6 were prepared through high temperature solid state reaction technique. Their phase structures, morphologies and luminescence properties were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM) and photoluminescence spectrometry. The most intense absorption of Y_2MoO_6 host occurred at 367 nm. Energy transfer from host lattice to Sm~(3+) ions could be observed, and the schematic diagram of energy transfer was constructed. The critical energy transfer distance and energy transfer mechanism between Sm~(3+) ions were discussed in detail. Considering the high color purity and appropriate emission intensity, Sm~(3+) doped Y_2 MoO_6 could be a promising phosphor under near ultraviolet light excitation.     

Luminescence and Energy Transfer Properties of Ca2Gd8(SiO4)6O2∶ A (A=Pb2+,Tm3+)Phosphors

Ca2Gd8(SiO4)6O2∶ A(A=Pb2 , Tm3 )phosphors were prepared through the sol-gel process. X-ray diffraction(XRD), scanning electron microscopy(SEM)and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 ℃. SEM study reveals that the average grain size is 300～1000 nm. In Ca2Gd8(SiO4)6O2∶ Tm3 phosphors, the Tm3 shows its characteristic blue emission at 456 nm(1D2-3F4)upon excitation into its 3H6 - 1D2(361 nm), with an optimum doping concentration of 1mol% of Gd3 in the host lattices. In Ca2Gd8(SiO4)6O2∶ Pb2 , Tm3 phosphors, excitation into the Pb2 at 266 nm(1S0-3P1)yields the emissions of Gd3 at 311 nm(6P-8S)and Tm3 at 367 nm(1D2 -3H6)and 456 nm(1D2-3F4), indicating that energy transfer processes of Pb2 - Gd3 and Pb2 - Tm3 have occurred in the host lattices.     

共沉淀分离-电感耦合等离子体原子发射光谱法测定含难熔金属岩石中12种稀土元素

准确测定稀土元素含量,对是否开采含难熔金属岩石的矿山中稀土元素具有重要指导意义。实验采用Na₂O₂在750℃马弗炉中熔融样品,熔融体冷却后用盐酸(1+4)转入烧杯中,往溶液中加入氨水,以样品做载体,共沉淀分离除去钠盐及能与氨水形成络氨离子的金属元素,沉淀物用稀氨水洗涤、热稀盐酸溶解,以电感耦合等离子体原子发射光谱法(ICP-AES)测定试液中La、Ce、Sm、Eu、Gd、Tb、Ho、Er、Dy、Tm、Yb、Y,建立了含难熔金属岩石中12种稀土元素的测定方法。各元素校准曲线的线性范围为0.10~25μg/mL,方法的检出限0.20~1.0μg/g。按照实验方法测定含难熔金属岩石物料中La、Ce、Sm、Eu、Gd、Tb、Ho、Er、Dy、Tm、Yb、Y等12种稀土元素,结果的相对标准偏差(RSD,n=9)为3.2%~6.2%,加标回收率为90%~110%。实验方法可用于含难溶金属岩石中稀土元素含量为0.001%~0.50%(质量分数)的测定。     

Oriented attachment(OA) mediated characteristic growth of Gd_2O_3 nanorods from nanoparticle seeds

Herein, we demonstrated the oriented attachment(OA) driven formation and characterization of Gd_2O_3 nanorods. The nanorods were synthesized via a surfactant free, inexpensive hydrothermal route and considering ~30 nm nanoparticles as the seed. While maintaining a cubic phase throughout the process, complete transformation of Gd_2O_3 nanoparticles to nanorods was found to occur at an elevated temperature(~180 oC) of the hydrothermal reaction. The elongated Gd_2O_3 nanostructures, as revealed from transmission electron microscopic imaging, possessed an average diameter of ~33 nm and an approximate length of 172 nm. From the kinetics of OA process, the activation energy of formation was estimated to be ~25 k J/mole. The existence of defect mediated radiative emission was ascertained from the asymmetric broadening of luminescence spectra. The defect emission arising from the Gd_2O_3 nanorods was nearly 1.4 times stronger than that of nanoparticles. The morphological evolution and growth kinetics were discussed along with the luminescence and electron paramagnetic resonance features.     

Synthesis and Characterization of Rare Earth Complexes of Ferrocenylcarbonylhydrazine

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