Gd2O3∶Eu3+纳米棒的制备与发光性能

在表面活性剂辅助的水热条件下合成出尺寸均一的Gd2O3∶Eu3+纳米棒, 对其结构和荧光性质进行了表征, 并对其生长机理进行了初步讨论. XRD结果表明, 水热前驱体样品为六方晶相的Gd(OH)3, 经过灼烧之后样品为立方相的Gd2O3. TEM照片表明, 所得样品为直径60 nm、长度约600 nm的纳米棒. 荧光光谱表明, 在波长为254 nm 的紫外光激发下, Gd2O3∶Eu3+纳米棒产生了不同于前驱体的特征红光发射, 对应于Eu3+ 的5D0-7F2跃迁, 表明Gd2O3是红色发光材料的良好基质.     

立方Gd2O3∶Eu纳米晶及光谱性质

用透射电镜拍摄球形ＣＧｄ２Ｏ３∶Ｅｕ纳米晶,并研究了室温下它的激发和发射光谱。结果表明,９００℃制备的体材料和相应的纳米晶相比,其激发光谱存在明显差异。前者以基质激发带为主导,电荷转移带（ＣＴＢ）很弱,而后者以ＣＴＢ为主。在绝缘体稀土氧化物中,可以忽略纳米效应对Ｅｕ３＋离子的４ｆ４ｆ能级跃迁的激发和发射光谱峰位的影响     

Gd3Ga5O12∶Eu3+发光纳米晶的燃烧合成及性质

以尿素为燃烧剂,乙二醇为分散剂采用燃烧法制备了Gd3Ga5O12∶Eu3+纳米晶。利用X射线衍射、电镜和荧光光谱对前驱体和热处理后样品的结构、形貌和发光性能进行了表征。XRD结果表明:700℃热处理2 h即可获得立方结构Gd3Ga5O12∶Eu3+纳米晶。根据Scherrer公式估算经700℃和900℃热处理2 h获得的纳米晶的一次性粒径分别为28 nm和42 nm。发射光谱和激发光谱的结果表明:特征发射峰来自于5D0-7FJ跃迁,而来自于Eu3+的5D0→7F1的磁偶极跃迁发射最强;宽激发带主要来自于Eu-O电荷迁移带和Gd3Ga5O12基质吸收。发射强度和激发强度随热处理温度的提高而增强。     

The effect of the size of raw Gd(OH)3 precipitation on the crystal structure and PL properties of Gd2O3:Eu

Our experiments show that cetyltrimethylammonium bromide (CTAB) has an obvious effect on the particle size of the precipitation of Gd(OH)3. Without CTAB, the particle size of the Gd(OH)3 precipitation is about 50 nm, whereas with CTAB, the particle size is less than 5 nm. We propose a mechanism where CTAB micelles work as a catalyst for the nucleation process and result in the precipitation of 5 nm particles. These small particles, after heat treatment at 1073 K, did not result in small Gd2O3 nanoparticles of the same size, but instead, forming crystals of 30-80 nm size in both cubic and monoclinic phases. When monitoring the photoluminescence (PL) peak at 610 nm, we found that the charge transfer state (CTS) absorption amplitude of Eu-O is reduced in the mixed structures. We speculate that the mixed structures modify the surface properties of the Gd2O3:Eu nanoparticles, leading to the reduction of Eu-O CTS absorption.     

Y2O3:Eu3+纳米线阵列的制备与表征

Y2O3:Eu3+红色荧光粉由于色纯度高、化学性质稳定和量子效率接近100%而广泛用于荧光灯和投影电视等方面.近年来,Y2O3:Eu3+的大量研究工作主要集中于纳米粉末的制备方法及其与体相材料不同的发光特性[1～3].最近,有关Y2O3:Eu3+及其稀土化合物的纳米管、纳米线和纳米带一维材料的制备成为研究热点.Wu Changfeng等[4,5]利用表面活性剂合成了Y2O3 : Eu3+纳米管.激光格位选择激发测试结果表明,Eu3+在纳米管中占据3个不同的格位,其611 nm处的红色发光峰出现了宽化.He Yu等[6]采用水热法及退火处理制备出了Y2O3:Eu3+纳米带,发现Eu3+的发射峰不仅宽化,而且出现了625 nm的新峰.Li Yadong等[7～9]采用水热法制备了稀土氧化物、硫氧化物和氢氧化物等的纳米线和纳米管,并探索了其形成机理,同时发现Y2O3S : yb3+,Er3+具有上转换的性质.     

Preparation of Gd(2)O(3) : Eu(3+) and Gd(2)O(2)S : Eu(3+) phosphor fine particles using an emulsion liquid membrane system

Size- (submicrometer-sized) and morphology- (spherical) controlled composite Gd-Eu oxalate particles were prepared in an emulsion liquid membrane (water-in-oil-in-water emulsion) system. The oxalate particles thus prepared were calcined in air to obtain Gd(2)O(3) : Eu(3+) phosphor particles and in sulfur atmosphere to obtain Gd(2)O(2)S : Eu(3+) phosphor particles. These submicrometer-sized spherical phosphor particles showed photoluminescence properties with emission peak at 614 nm for Gd(2)O(3) : Eu(3+) and 628 nm for Gd(2)O(2)S : Eu(3+).     

Vacuum Ultraviolet Excited Photoluminescence Properties of Y202S:Eu3+,Bi3+ Phosphor

As an Hg-free lamp using phosphor,the Bi3+ and Eu3+ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum uitraviolet(VUV) excitation were investigated.The VUV photolumineseent intensity of Y2O2S:Eu3+ was weak,however,considerably stronger red emission at 626 nm with good color purity was observed in Y2O2S:Eu3+,Bi3+ systems.Investigation on the photoluminescence reveals that the strong VUV luminescence of Y2O2S:Eu3+,Bi3+ at 147 nm is mainly because the Bi3+ acts as a medium and effectively performs the energy transfer process: Y3+-O2→Bi3+→Eu3+,while the intense emission band at 172 nm is attributed to the absorption of the characteristic 1So-1P1 transition of Bi3+ and the direct energy transfer from Bi3+ to Eu3+.The Y2O2S:Eu3+,Bi3+ shows excellent VUV optical properties compared with the commercial (Y,Gd)BO3:Eu3+.Thus,the Y2O2S:Eu3+,Bi3+ can be a potential red VUV-excited candidate applied in Hg-free lamps for backlight of liquid crystal display.     

Highly uniform and monodisperse Gd(2)O(2)S:Ln(3+) (Ln = Eu, Tb) submicrospheres: solvothermal synthesis and luminescence properties

Gd(2)O(2)S:Ln(3+) (Ln = Eu, Tb) submicrospheres were successfully prepared through a facile and mild solvothermal method followed by a subsequent heat treatment. X-ray diffraction (XRD) results demonstrate that all the diffraction peaks of the samples can be well indexed to the pure hexagonal phase of Gd(2)O(2)S. The energy dispersive spectroscopy (EDS), element analysis, and FT-IR results show that the precursors are composed of the Gd, Eu, O, S, C, H, and N elements. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that these spheres are actually composed of randomly aggregated nanoparticles. The formation mechanism for the Gd(2)O(2)S:Ln(3+)(Ln = Eu, Tb) spheres has been proposed on an isotropic growth mechanism. Under ultraviolet excitation, Gd(2)O(2)S:Ln(3+)(Ln = Eu, Tb) spheres show red and green emission corresponding to the (5)D(0)→(7)F(2) transition of the Eu(3+) ions and the (5)D(4)→(7)F(5) transition of the Tb(3+) ions. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide oxysulfides.     

RESr2RuCu2O8(RE=Gd和Eu)的合成与物性研究

报道了磁性超导体RESr2RuCu2O8(RE=Gd和Eu)单相样品的合成以及对其结构和物性的研究。结果表明，这类化合物的结构和YBa2Cu3O7-δ相类似；在这两类化合物中，超导电性与弱铁磁有序共存；两样品铁磁相变温度TM分别为136，130K，超导临界温度TC分别为46，35K；由于Gd^3 和Eu^3 离子磁矩的不同，两样品的磁性质存在一定的差别。     

Synthesis and Fluorescence Properties of Eu^2＋-Doped KMgF3 Nanoparticles

Introduction Nanomaterialsusuallyshowsomenoveloptical,electronic,magneticandchemicalpropertiessignifi cantlydifferentfromthoseofthebulkmaterialsbecause oftheirextremelysmallsize,largespecificsurfaceare asandpeculiarquantumsize.Thepotentialoftheirap plicat…     

YF3:Eu3+纳米纤维/高分子复合纳米纤维的制备与表征

采用静电纺丝技术制备了Y2O3:Eu3+纳米纤维,使用NH4HF2为氟化剂,经双坩埚法氟化和脱氨后得到YF3:Eu3+纳米纤维,再采用静电纺丝技术制备了YF3:Eu3+纳米纤维/PVP复合纳米纤维. XRD分析表明,立方相的Y2O3:Eu3+氟化后,得到了正交相的YF3:Eu3+纳米纤维,空间群为Pnma;YF3:Eu3+纳米纤维/PVP复合纳米纤维具有明显的YF3:Eu3+的衍射峰. SEM分析表明,YF3:Eu3+纳米纤维与YF3:Eu3+纳米纤维/PVP复合纳米纤维的直径分别为91±11 nm、319±43 nm,表面光滑. 用Shapiro-Wilk方法检验,纤维直径属于正态分布. 荧光光谱分析表明,YF3:Eu3+纳米纤维和YF3:Eu3+纳米纤维/PVP复合纳米纤维的最强发射峰均位于588 nm和595 nm,属于Eu3+的5D0→7F1跃迁,表明Eu3+占据YF3基质中Y3+晶格点的C2对称格位. PVP对YF3:Eu3+发光峰位没有影响,但发光强度降低;YF3:Eu3+的含量与YF3:Eu3+纳米纤维/PVP复合纳米纤维的发光强度成线性关系.     

Preparation of Y2O3:Eu3+ nanoparticles in reverse micellar systems and their photoluminescence properties

Y2O3:Eu3+ phosphor nanoparticles (4-8 nm in size) with spherical morphology and narrow size distribution were obtained by calcination of composite Y-Eu hydroxide nanoparticles, which were prepared in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane or polyethylene glycol mono-4-nonylphenyl ether (NP-5)/cyclohexane reverse micellar systems. This was achieved by the incorporation of the Y-Eu hydroxide nanoparticles into polyurea (PUA) via in situ polymerization of hexamethylene diisocyanate (HDI) in the reverse micellar solution and subsequent calcination of the resulting PUA materials. The emission intensity of the Y2O3:Eu3+ nanoparticles, prepared in the AOT/isooctane system, was significantly lower than that of the micrometer-size particles prepared in a homogeneous aqueous solution, since the calcined nanoparticles contained Na2SO4 impurity derived from the remaining AOT surfactant. The nanoparticles prepared in the NP-5/cyclohexane system, in contrast, showed higher emission intensity compared to the nanoparticles prepared in the AOT/isooctane system and longer luminescence lifetime compared to the micrometer-size particles prepared in the homogeneous aqueous solution. The photoluminescence intensity of Y2O3:Eu3+, prepared via the proposed process was found to decrease with decreasing the particle size.     

Optical characterization of eu-doped and undoped gd(2)o(3) nanoparticles synthesized by the hydrogen flame pyrolysis method

Rare-earth-doped nanoparticles are promising materials for fluorescent labeling, as they are characterized by a high Stokes shift, narrow emission spectra, long lifetimes, minimized photobleaching, and low toxicity. We examined the structural and optical properties of europium-doped gadolinium oxide nanoparticles synthesized by the flame pyrolysis method, with specific emphasis on full spectral characterization and fluorescence kinetics. The emission-excitation characterization revealed the presence of predominantly monoclinic but also highly luminescent cubic phases with a prominent oxygen-to-europium charge-transfer band in the 230-260 nm range. A broad emission band in the visible region, corresponding to a similar band in undoped Gd(2)O(3), related to the matrix surface defects, was observed in time-gated spectroscopy of doped nanopowders. All of the examined nanopowders showed very short decay components, on the order of 2 ns, and much longer millisecond decay times characteristic of lanthanide ions. At intermediate times, on the order of 20-100 ns, a complex behavior of the decay was observed, indicative of progressive energy transfer to the lanthanide ion, which varied with different intrashell transitions. Structural characterization data by means of XRD measurements allowed for unambiguous determination of the Eu:Gd(2)O(3) crystallographic structure and cell dimensions to be consistent with a predominantly monoclinic phase.     

Preparation and photoluminescence properties of Y2SiO5:Eu3+ nanocrystals

The sol-emulsion-gel method is used for the preparation of about 5-7 nm size Eu2O3 doped and coated Y2SiO5 nanoparticles at 1300 degrees C. Here, we report the role of surface coating, dopant concentration and temperature of heating on the modification of crystal structure and the photoluminescence properties of Y2SiO5:Eu3+ nanocrystals. It is found that photoluminescence properties are sensitive to the crystal structure which is again controlled by surface coating, concentration and heating temperature. The decay times are 0.76, 1.14, 1.23 and 1.40 ms for 0.25, 0.5, 1.0 and 2.5 mol% Eu2O3 doped Y2SiO5 nanocrystals prepared at 1100 degrees C (X1-Y2SiO5). However, in X2-Y2SiO5 crystal phase (at 1300 degrees C) the average decay times are 1.05, 1.35, 1.55 and 1.60 ms for 0.25, 0.5, 1.0 and 2.5 mol% Eu2O3 doped Y2SiO5 nanocrystals, indicating the photoluminescence properties depend on both the crystal structure and the concentration of ions. The emission intensity of the peak at 612 nm (5D0-->7F2) of the Eu3+-ions is found to be sensitive to the doping and surface coating of Y2SiO5 nanocrystals. The decay times are 1.55 and 1.70 ms for 1300 degrees C heated 1.0 mol% Eu2O3 doped and coated Y2SiO5 nanocrystals, respectively. Our analysis suggests that the site symmetry of ions plays a most important role in the modification of radiative relaxation mechanisms and as a result on the overall photoluminescence properties.     

YTaO4：Gd,Eu体系光致发光中的能量传递

Yttrium orthotantalate co doped by Eu 3+ and Gd 3+ has been synthesized by solid state method. The emission and excitation spectra of YTaO4: Gd, Eu are studied in detail. In the excitation spectra of Eu 3+5D 0→ 7F2 transition emission in YTaO4:Gd, Eu, there appear excitations of Gd3+ and TaO43- group, which indicate energy transfer from Gd 3+ and TaO4 3- group to Eu 3+ in the process of luminescence. The excitation spectra of Gd 3+ emission(λ=312 5 nm) including strong excitation of charge transfer of group show energy transfer from host lattice to Gd 3+ . So there are two ways of energy transfer in YTaO4:Gd,Eu system. The strong evidences from excitation spectra, emission spectra and diffusive reflection spectra of this system show that Gd 3+ can play an intermediate role in the process of luminescence. There is energy transfer from TaO 3- 4 to Gd 3+ and finally to Eu 3+ via the charge transfer state and spectral overlap. The energy transfer from TaO 3- 4 to Gd 3+ is a dominating process in this system.     

Li_2O－Ln_2O_3－SiO_2：Eu~（3＋），Bi~（3＋）体系的结构

采用ｓｏｌ－ｇｅｌ法合成了系列发光体Ｌｉ２Ｏ－Ｌｎ２Ｏ３－ＳｉＯ２：Ｅｕ３＋，Ｂｉ３＋，并确定了发光体的物相结构．当Ｌｎ３＋＝Ｙ３＋和Ｌｎ３＋＝Ｌａ３＋时，紫外光激发下Ｅｕ３＋的发射分别以红光和橙光为主，只存在一种Ｅｕ３＋发光中心；Ｌｎ３＋＝Ｇｄ３＋时，至少存在两种Ｅｕ３＋发光中心和两种Ｂｉ３＋发光中心（共掺杂Ｅｕ３＋，Ｂｉ３＋），Ｂｉ３＋的吸收和发射所处的能量位置最低，４ｆ格位的Ｂｉ３＋发生了向Ｅｕ３＋的有效能量传递．     

Phase structure and luminescence properties of Eu3+-doped TiO2 nanocrystals synthesized by Ar/O2 radio frequency thermal plasma oxidation of liquid precursor mists

Eu3+-doped TiO2 luminescent nanocrystals have been synthesized in this work via Ar/O2 thermal plasma oxidizing mists of liquid precursors containing titanium tetra-n-butoxide and europium(III) nitrate, with varied O2 input in the plasma sheath (10-90 L/min) and Eu3+ addition in the precursor solution (Eu/(Ti + Eu) = 0-5 atom%). The resultant nanopowders are mixtures of the anatase (30-36 nm) and rutile (64-83 nm) polymorphs in the studied range, but the rutile fraction increases steadily at a higher Eu3+ addition, as revealed by X-ray diffraction (XRD) and Raman spectroscopy, because of the creation of oxygen vacancies in the TiO2 gas clusters by substitutional Eu3+ doping. The amount of Eu3+ that can be doped into a TiO2 lattice was limited up to 0.5 atom%, above which Eu2Ti2O7 pyrochlore was formed in the final products. High resolution transmission electron microscopy (HRTEM) observation indicates that the particles are dense and have sizes ranging from several nanometers up to 180 nm. Efficient nonradiative energy transfer from the TiO2 host to Eu3+ ions, which was seldom reported in the wet-chemically derived nanoparticles or thin films of the current system, was confirmed by combined studies of excitation, UV-vis (ultraviolet-visible), and PL (photoluminescence) spectroscopy. As a consequence of this, bright red emissions were observed from the plasma-generated nanopowders either by exciting the TiO2 host with UV light shorter than 405 nm or by directly exciting Eu3+ at a wavelength beyond the absorption edge (405 nm) of TiO2.     

水热法制备多层核壳结构Gd_2O_3:Eu~(3+)空心微球

以稀土硝酸盐-葡萄糖的混合溶液作为前驱体,采用一步水热法和随后的热处理得到了多层核壳结构Gd_2O_3:Eu~(3+)空心微球,并用X-射线衍射(XRD)、场发射扫描电镜(FESEM)、透射电镜(TEM)、X-射线能量色散光谱(EDS)和荧光光谱等测试手段对所得样品进行了表征.结果表明:所得空心球样品为纯的立方相的Gd_2O_3.具有规则的多层核壳空心结构,空心球的直径在2～3μm左右,壁厚约为100 nml,并且Gd_2O_3:Eu~(3+)空心球是由尺寸约为30 nm的球形纳米颗粒白组装而成.样品中含有Gd、Eu、O元素.该空心球样品具有强的Eu~(3+)的特征红光发射以及长的荧光寿命,可以用来作为时间分辨荧光标记物.     

The effects of Gd3+ substitution on the crystal structure, site symmetry, and photoluminescence of Y/Eu layered rare-earth hydroxide (LRH) nanoplates

Well crystallized nanoplates of the (Y(0.95-x)Gd(x)Eu(0.05))(2)(OH)(5)NO(3)·nH(2)O ternary layered rare-earth hydroxides (LRHs), synthesized hydrothermally, have been investigated with emphasis on the effects of Gd(3+) substitution for Y(3+) on the structural features and optical properties. Characterizations of the materials were achieved by the combined techniques of XRD, FT-IR, TEM, DTA/TG, and optical spectroscopies. The results showed that Gd(3+) substitution leads to linearly expanded ab plane, shortened interlayer distance (c/2), and reduced hydration (smaller n value) of the crystal structure. As a consequence, the Ln(3+) partially shifts from the C(4v) to C(1) site symmetries and thus leads to systematically altered photoluminescence behaviors. Under the (7)F(0)→(5)L(6) transition excitation of Eu(3+) at 394 nm, both the (5)D(0)→(7)F(2) to (5)D(0)→(7)F(4) and the 595 nm (5)D(0)→(7)F(1) to 590 nm (5)D(0)→(7)F(1) intensity ratios linearly increase towards a higher Gd(3+) content. The incorporated Gd(3+) cations selectively sensitize emission from the C(1)-site Eu(3+) and produce a new charge transfer (CT) excitation band at ～254 nm. With this, the desired 615-nm red emission is obtainable either under intra-4f(6) transition excitation of Eu(3+) or by exciting the CT band. The materials have similar fluorescence lifetimes of 0.85 ± 0.05 ms for the 615-nm emission, irrespective of the Gd(3+) content and excitation wavelength.     

Synthesis and spectroscopic behavior of highly luminescent Eu(3+)-dibenzoylmethanate (DBM) complexes with sulfoxide ligands

In this paper the synthesis, characterization and photoluminescent behavior of the [RE(DBM)3L2] complexes (RE=Gd and Eu) with a variety of sulfoxide ligands; L=benzyl sulfoxide (DBSO), methyl sulfoxide (DMSO), phenyl sulfoxide (DPSO) and p-tolyl sulfoxide (PTSO) have been investigated in solid state. The emission spectra of the Eu(3+)-beta-diketonate complexes show characteristics narrow bands arising from the 5D0-->7F(J) (J=0-4) transitions, which are split according to the selection rule for C(n), C(nv) or C(s) site symmetries. The experimental Judd-Ofelt intensity parameters (Omega2 and Omega4), radiative (A(rad)) and non-radiative (A(nrad)) decay rates, and R02 for the europium complexes have been determined and compared. The highest value of Omega2 (61.9x10(-20)cm2) was obtained to the complex with PTSO ligand, indicating that Eu3+ ion is in the highly polarizable chemical environment. The higher values of the experimental quantum yield (q) and emission quantum efficiency of the emitter 5D0 level (eta) for the Eu-complexes with DMSO, DBSO and PTSO sulfoxides suggest that these complexes are promising Light Conversion Molecular Devices (LCMDs). The lower value of quantum yield (q=1%), for the hydrated complex [Eu(DBM)3H2O], indicates that the luminescence quenching occurs via multiphonon relaxation by coupling with the OH-oscillators from water molecule coordinated to rare earth ion. The pure red emission of the Eu-complexes has been confirmed by (x, y) color coordinates.