Y2O2SO4: Eu3+ 亚微米棒的合成及发光性能

以Na2SO4和K2SO4为熔盐,采用熔盐法合成了一维Y2O2SO4:Eu3+亚微米棒。应用X射线衍射、扫描电子显微镜和光谱仪等方法对合成产物的晶体结构、形貌和发光性能进行表征。考察了烧结温度、Eu3+掺杂浓度对合成产物的晶体结构、形貌和发光性能的影响,结果表明,原料混合物在1100℃空气中煅烧2 h可合成纯相、表面光滑的Y2O2SO4: Eu3+亚微米棒,Y2O2SO4: Eu3+亚微米棒的长边大于10 μm,短边为500~800 nm。在270nm紫外光的激发下,Y2O2SO4: Eu3+亚微米棒呈红光发射,最强发射峰位于616 nm处,归属于Eu3+的5D0→7F2跃迁,Y2O2SO4: Eu3+亚微米棒Eu3+的最佳掺杂浓度为10mol%。     

Y_2O_2SO_4:Eu~(3+)亚微米棒的合成及发光性能（英文）

以Na_2SO_4和K_2SO_4为熔盐,采用熔盐法合成了一维Y_2O_2SO_4:Eu~(3+)亚微米棒。应用X射线衍射、扫描电子显微镜和光谱仪等方法对合成产物的晶体结构、形貌和发光性能进行表征。考察了烧结温度、Eu3+掺杂浓度对合成产物的晶体结构、形貌和发光性能的影响。结果表明,原料混合物在1100℃空气中煅烧2 h可合成纯相、表面光滑的Y_2O_2SO_4:Eu~(3+)亚微米棒,Y_2O_2SO_4:Eu~(3+)亚微米棒的长度大于10μm,宽度为500～800 nm。在270 nm紫外光的激发下,Y_2O_2SO_4:Eu~(3+)亚微米棒呈红光发射,最强发射峰位于616 nm处,归属于Eu3+的5D0→7F2跃迁,Y_2O_2SO_4:Eu~(3+)亚微米棒Eu3+的最佳掺杂浓度为10mol%。     

沉淀法制备纳米Eu：Y2O3荧光粉

试验分别以微米级Y2O3、Eu2O3粉体为原料，碳酸氢铵为沉淀剂，三乙醇胺为络合剂，采用三乙醇胺络合沉淀法制备了化学组成为NC6H12（NH4）Y2（CO3）（NO3）2·nH2O的前驱体。研究了前驱体在不同的煅烧温度下的物相变化，结果表明，前驱体在500℃保温2h即可直接生成立方相的Eu：Y2O3，在1000℃保温2h的条件下得到了结晶度高、分散性好、平均粒径为50～60nm、近球形的纳米Eu：Y2O3荧光粉。     

室温固相反应前驱体法合成稀土磷酸盐绿色荧光粉

采用室温固相化学反应前驱体法合成了亚微米级的(La,Ce,Tb)PO4绿色荧光粉.利用热重-差示热分析(TG-DTA)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等实验技术,研究了荧光粉的形成过程,并对粉体尺寸、形貌及发光性能进行研究.结果表明:将前驱体在900℃煅烧后,产物为单斜晶系、独居石结构的正磷酸盐.粉末为亚微米级的球形颗粒.在272 nm紫外线激发下发绿色荧光,发射主峰在548 nm.同时表明:用室温固相化学反应前驱体法合成的(La,Ce,Tb)PO4是1种性能优良的荧光粉.     

（Y，Gd）2O3：Eu^3＋纳米粒子制备及光谱特性

用湿化学共沉淀法制备了(Y,Gd)2O3:Eu3 纳米粒子.用XRD,TEM,SEM及差示/热重分析(DSC/TG)手段对粉体进行了表征.用荧光光度计分析了样品的激发光谱和发射光谱.结果表明:在煅烧温度为800℃保温2 h时,合成出近似球形、粒径均匀且分散性好的(Y,Gd)2O3:Eu3 纳米粒子,一次颗粒尺寸约为20 nm.样品在波长为612.0 nm监控光下激发,出现235和250 nm两个激发峰,分别为(Y,Gd)2O3基质吸收和Eu3 迁移态(CTS)吸收造成的.两个波长激发下的发射光谱峰强度前者高于后者.当掺杂Eu3 的摩尔浓度为3%时,发射光谱对应5D0→7F2能级跃迁的相对峰强度最大,当Eu3 掺杂的摩尔浓度为7%时,相对峰强度反而降低,这是由于Eu3 的浓度猝灭造成的.     

SrB4O7:Eu,Ce荧光粉的合成及其发光特性研究

用高温固相法合成了SrB4O7:Eu和SrB4O7:Eu:Ce荧光粉,研究了荧光粉的吸收光谱和荧光光谱.结果表明,通过250 nm的激光二极管激发,SrB4O7:Eu荧光粉在室温下,被观察到Eu2 离子6P7/2→8S7/2跃迁产生的紫外光(385nm)和Eu3 离子5D0→7F1、5D0→7F2、5D0→7F2、5D0→7F3、5D0→7F4跃迁分别产生的橙色光(590nm)、红光(614nm)、红光(660nm)、深红色光(720nm);在Eu和Ce共掺的荧光粉中,Ce2 离子敏化Eu2 离子发光,Eu2 离子发射的紫外光强度增加,而Eu3 的发射光减弱.     

喷雾干燥法合成纳微多孔球形LiFePO_4/C锂离子电池正极材料（英文）

为提高LiFePO_4(LFP)正极材料的电化学性能,采用喷雾干燥结合煅烧工艺合成具有纳微结构和多孔结构的球形LFP/C材料。结果表明,当煅烧温度高于500°C时,粒径尺寸为0.5~5μm的球形前驱体可以完全转化为LFP/C材料。当煅烧温度为700°C时,所得的LFP/C微米球形颗粒是由大量粒径约为20 nm的颗粒及发育良好且相互连通的孔道组成,其比表面积为28.77 m~2/g。在0.5C、1C和2C的电流倍率下恒流充放电时,700°C时所得LFP/C材料的放电比容量分别为162.43、154.35和144.03 m A·h/g,且50次循环后的容量保持率达到100%。该材料所具有良好的电化学性能得益于其较小的Li+扩散阻抗和特殊的微观结构。     

亚微米球形镍粉的两步法可控制备与表征

以H_2C_2O_4·2H_2O为沉淀剂,NiSO_4·6H_2O为镍源,第1步通过共沉淀法制得NiC2O4前驱体粉末;然后在H_2气氛、中温条件下(250~500℃)煅烧还原,第2步制得高规则度的亚微米球形镍粉。采用扫描电子显微镜、X射线衍射、激光粒度分析等检测手段对所制备的样品形貌、显微结构进行表征。结果表明:亚微米球形镍粉纯度高,二次颗粒粒径约为40μm,由大量大小均匀、分散性好的粒径0.5μm左右的一次颗粒团聚而成,这种结构保证了镍粉具有良好的成形性和烧结活性。随煅烧温度的升高,结晶度逐渐升高;亚微米球形镍粉的最佳制备工艺参数为:镍离子浓度0.7mol·L~(-1),反应温度40℃和煅烧温度500℃。镍粉的晶粒长大活化能为26.9kJ·mol~(-1),其晶粒长大机制为界面扩散控制机制。     

PREPARATION AND CHAIACTERISTICS OF (Y,Gd)2O3:Eu3+ NANOPARTICLES

用湿化学共沉淀法制备了(Y, Gd)2O3:Eu3+纳米粒子. 用XRD, TEM, SEM及差示/热重分析 (DSC/TG)手段对粉体进行了表征. 用荧光光度计分析了样品的激发光谱和发射光谱. 结果表明： 在煅烧温度为800 ℃保温2 h时, 合成出近似球形、粒径均匀且分散性好的(Y, Gd)2O3:Eu3+纳米粒 子, 一次颗粒尺寸约为20 nm. 样品在波长为612.0 nm监控光下激发, 出现235和250 nm两个激发 峰, 分别为(Y, Gd)2O3基质吸收和Eu3+迁移态(CTS)吸收造成的. 两个波长激发下的发射光谱峰强 度前者高于后者. 当掺杂Eu3的摩尔浓度为3%时, 发射光谱对应5D07F2 能级跃迁的相对峰强度 最大, 当Eu3+掺杂的摩尔浓度为7%时, 相对峰强度反而降低, 这是由于Eu3+的浓度猝灭造成的.     

共沉淀-热处理工艺合成YAG:Ce3+荧光粉的研究

采用共沉淀法制各Y3Al5O12:Ce3 (YAG:Ce3 )荧光体前驱粉末,采用差热分析(DTA)、傅里叶红外(FT-IR)、X-射线衍射(XRD)和荧光光谱(PL)等测试分析手段,对凝胶经不同温度烧成的Y3Al5O12:Ce3 荧光粉的成相过程、晶体结构及其发光性能进行了测试与分析.DTA和XRD结果表明,经1200℃煅烧后,凝胶转变为单相性良好的YAG立方相,空间群为Ia3d(230).PL谱测试结果表明,煅烧热处理获得的YAG:Ce3 荧光粉的激发光谱由2个主峰位于340nm和469 nm的激发峰组成,分别对应于2F5/2→5D和2F7/2→5D的跃迁;发射谱主峰位于537 nm,属于Ce3 的5d→4f特征跃迁发射.不同Ce掺杂浓度的YAG:Ce3 荧光粉的发光性能研究结果表明,随着Ce掺杂浓度增加,荧光粉发光强度先增加后减小,呈现浓度淬灭现象,当x=0.06时,发光强度达到最大值.     

Morphology-dependent crystallization and luminescence behavior of (Y, Eu)2O3 red phosphors

(Y_0.95Eu_0.05)₂O₃ red phosphor particles with three distinctive morphologies of submicron spheres (up to 180 nm), microflowers (up to 10 μm) and microplates (up to 50 × 10 μm) have been converted from their respective precursors autoclaved (100–180 °C, 12 h) from mixed solutions of the component nitrates and hexamethylenetetramine [(CH₂)₆N₄]. The three types of precursors were found to have the approximate compositions M(OH)CO₃·H₂O for the sphere (M = Y and Eu), M₄O(OH)₉NO₃ for the flower and M₂(CO₃)₃·3H₂O for the plate, and their formation domains were defined. Both X-ray diffraction and photoluminescence analysis indicated that a calcination temperature of ?800 °C is needed to attain a homogeneous (Y_0.95Eu_0.05)₂O₃ solid solution and thus improved luminescence. Morphology-confined crystal growth of (Y_0.95Eu_0.05)₂O₃ was observed from the microplates, yielding a significantly higher exposure of the (4 0 0) facets at elevated temperature. The three types of phosphors exhibited a substantial morphology-dependent photoluminescence (PL)/photoluminescence excitation (PLE) behavior, but did not differ much in the positions of the PLE/PL bands or in the asymmetry factor [I(⁵D₀ → ⁷F₂)/I(⁵D₀ → ⁷F₁)] of the luminescence. Upon UV excitation into the charge transfer band at ～240 nm the microplates showed the strongest red emission at ～613 nm (the ⁵D₀ → ⁷F₂ transition of Eu³⁺) at a calcination temperature of 1000 °C, whose intensity was ～2.49 and 1.57 times those of the flowers and spheres, respectively. Fluorescence decay analysis yielded similar lifetimes of ～1.5 ± 0.1 ms for the 613 nm emission of the three morphologies, suggesting that the differing luminescence was largely morphology-dependent, rather than defect-dependent.     

VUV luminescence properties of Y0.95Eu0.05PO4 phosphor derived by a modified solid-state route

A modified solid-state route was attempted to prepare Y0.95 Eu0.05PO4 PDP phosphor,involving milling a powdered mixture of YCl3,EuCl3,and (NH4)2HPO4 and calcining the milling-derived precursor.The thermal decomposition behavior of the milling-derived precursor was investigated by thermogravimetric analysis (TGA).Phase compositions,morphologies,and luminescence properties of the prepared phosphor powder were characterized by X-ray diffraction (XRD),scanning electron microscope (SEM),and vacuum ultraviolet (VUV) emission spectra,respectively.The results indicated that the Y0.95Eu0.05PO4 phosphor powder obtained at a calcination temperature of 900℃ was xenotime-structured.The phosphor powder particles were uniform and spherical-shaped with a primary particle size of～200 nm.In comparison with that derived by the conventional solid-state route,the phosphor powder prepared by the modified solid-state route exhibited a higher color purity,presenting a predominant emission peak at 619 nm under 147 nm VUV excitation.     

Synthesis and optical studies of gamma irradiated Eu doped nanocrystalline CaF2

Europium (Eu) doped Calcium fluoride (CaF₂) nanoparticles are synthesized by co-precipitation method and characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Also, optical absorption and photoluminescence (PL) results on gamma irradiated Eu doped CaF₂ nanoparticles are presented. The PXRD patterns confirmed the cubic crystallinity of the samples and the particle size is found to be ∼25 nm. The purity of the synthesized nanoparticles is confirmed from FTIR spectrum. The morphological features studied using SEM revealed that nanoparticles are agglomerated and porous. Optical absorption spectrum shows that γ-rayed Eu doped CaF₂ nanoparticles exhibit absorption bands at ∼279, 360 and 434 nm. The PL studies showed emission at ∼420, 525 and 552 nm.     

Lu_2O_3:Yb~(3+),Tm~(3+)纳米晶的制备和上转换发光性能(英文)

采用碳酸氢铵(NH4HCO3)为沉淀剂,用共沉淀法制备Yb3+和Tm3+共掺杂的Lu2O3:Yb3+,Tm3+纳米晶。研究Tm3+摩尔分数、Yb3+摩尔分数和煅烧温度对Lu2O3:Yb3+,Tm3+纳米晶的结构和上转换发光性能的影响。结果表明:所制备的纳米晶具有纯的Lu2O3相,结晶性较好。当掺杂的Tm3+浓度超过0.2%(摩尔分数)时,出现浓度淬灭效应。Tm3+和Yb3+的最佳掺杂比分别为0.2%和2%(摩尔分数)。在980nm半导体激光器的激发下,样品发射出蓝光(490nm)和红光(653nm),分别对应Tm3+的1G4→3H6和1G4→3F4跃迁。发射强度与激发功率的关系表明,Tm3+的1G4能级布居是三光子能量传递过程。随着煅烧温度的升高,上转换发光强度增强,这主要是因为随着温度的升高纳米晶表面的OH?减少和纳米晶尺寸增大。     

Preparation and luminescent properties of Eu doped Sr3La(PO4)3 phosphor

Eu²⁺-doped Sr₃La(PO₄)₃ phosphors were synthesized by solid-state reaction method. Their luminescent properties were investigated. The phosphor could be excited by ultraviolet light effectively. The emission spectra exhibit two emission peaks located at 418 nm and 500 nm, respectively. These two peaks originated from two different luminescent centers, respectively. One is nine-coordinated Eu(I) center, other is six-coordinated Eu(II) center. It was found that the doping concentration of Eu²⁺ ions affected the shape of emission spectra. As the doping concentration increasing, Eu²⁺ ions are more likely to form Eu(I) luminescent centers and emit purple light.     

Y2Cu2O5光催化剂的制备及模拟太阳光催化产氢

分别用固相法和液相法制备Y2Cu2O5光催化剂,利用热重差热分析(TG-DTA)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见光漫反射光谱(UV-Vis DRS)等技术对光催化剂进行表征。在模拟太阳光照射条件下,以草酸(H2C2O4)为牺牲剂对所制得的光催化剂制氢性能进行评价,考察制备方法和牺牲剂类型等因素对其产氢性能的影响以及光催化剂的稳定性能。结果表明:溶胶凝胶法所得样品中含有Y2O3杂质,为Y2Cu2O5与Y2O3的混合物;固相法所得样品为纯净的Y2Cu2O5,具备较高的光催化产氢活性。用固相法制备的光催化剂Y2Cu2O5,当其用量为0.8 g/L、草酸为牺牲剂且初始浓度为0.05 mol/L时,表现出最佳光催化产氢活性,其产氢量为3.78mmol/(h.g)。但Y2Cu2O5在草酸溶液中不稳定,会与草酸反应生成Y2(C2O4)3.2H2O,导致产氢活性降低。     

Synthesis of Y2O3：Eu^3＋ phosphors by surface diffusion and their photoluminescence properties

Y2O3:Eu3+ phosphors were synthesized by the surface diffusion method (SDM). X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS) were used to characterize the structure, morphology and component of Y2O3:Eu3+ phosphors. The photoluminescent (PL) properties were also investigated. The results reveal that the PL intensity of Y2O3:Eu3+ phosphors prepared by the surface diffusion method (SDM) is much higher than that prepared by homogeneous co-precipitation. Th...     

溶胶-凝胶法制备Y2O3掺杂ZnO压敏薄膜及其电性能（英文）

研究溶胶-凝胶法制备不同浓度Y2O3掺杂对ZnO-Bi2O3压敏薄膜微观结构和电性能的影响。研究结果表明:Y2O3掺杂ZnO薄膜在750°C空气气氛下退火1h,ZnO薄膜的特征峰与ZnO的六方纤锌矿结构相匹配;ZnO晶粒直径随着掺杂量的增加而减小,Y2O3稀土掺杂氧化锌晶粒细化;薄膜厚度均匀且每一层厚度约80nm。研究结果还表明:当Y3+掺杂浓度为0.2%(摩尔分数)时,ZnO薄膜的非线性伏安特性最好,其漏电流为0.46mA,电位梯度为110V/mm,非线性系数为3.1。     

Hf6Ta2O17材料的合成和热膨胀性能

以HfO2、Ta2O5粉体为原料,采用固相法合成Hf6Ta2O17材料。在空气气氛下1600℃常压烧结8h制备块体试样。用X射线衍射(XRD)仪检测合成粉体的相结构,通过场发射扫描电镜(SEM)观察试样的微观形貌,用热膨胀仪检测试样的热膨胀系数(TEC)。结果表明:固相法可以制备纯净单相的Hf6Ta2O17材料和比较致密的块体试样;Hf6Ta2O17材料在20~1400℃温度范围内没有相变,其高温相稳定性优于YSZ材料;Hf6Ta2O17在1200℃的热膨胀系数为9.59×10-6/℃,与YSZ材料的热膨胀系数接近,有望用于热障涂层。     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。