纳米晶Y_2O_3∶Eu~(3+)的合成及其热分析动力学

以Y(NO3)3、Eu2O3、CO(NH2)2为原料,使用超声波作用下的均匀沉淀法合成了纳米晶荧光粉Y2O3∶Eu3+。利用不同升温速率的热重及差热分析研究了纳米晶Y2O3∶Eu3+的合成动力学及晶粒生长动力学。研究表明,纳米晶Y2O3∶Eu3+的前驱体分解过程可分为3个步骤,利用Doyle-Ozawa法和Kissinger法分别计算了各个反应阶段的表观活化能,用Kissinger法确定每个反应阶段的反应级数和频率因子,并给出了各个阶段的动力学方程。根据晶粒生长动力学理论计算纳米荧光粉Y2O3∶Eu3+晶粒生长活化能为17.80kJ·mol-1,表明热处理过程中纳米晶粒的长大为扩散生长机制。     

Y2O2S∶Eu3+空心微球的制备与性能

以单分散的碳球为硬模板,采用均匀共沉淀法合成了Y2O2S:Eu3+心微球.通过XRD、SEM、TEM、荧光光谱对其进行表征.X射线衍射测试表明所制备的Y2O2S:Eu3+空心微球为单相,六方晶.扫描电子显微镜(SEM)和透射电子显微镜(TEM)测试表明所制备的Y2O2S:Eu3+空心微球粒径小,分布均匀.激发和发射光谱测试表明Eu3+离子能有效地掺入硫氧化钇基质中,并具有良好的发光性能.     

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.     

稀土纳米复合氧化物RE_2O_3∶Eu(RE=Y,Gd)的制备及特性

以甘氨酸辅助的燃烧法和非晶态稀土DTPA配合物前驱体热分解法制备了Y2 O3 ∶Eu和Gd2 O3 ∶Eu纳米材料。X射线衍射表明燃烧法和配合物前驱体热分解法制备的纳米Y2 O3 ∶Eu均为立方相 ,而Gd2 O3 ∶Eu纳米材料则随制备条件不同可得到立方相或单斜相两种产物 ,发射光谱证实了这一结论。通过透射电子显微镜、扫描电子显微镜对不同方法制备的纳米材料的尺寸、形貌也进行了表征     

Gd_2O_3:Eu~(3+)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.     

La_2O_2S∶Mn~(2+)荧光粉的微波合成及其荧光特性

目前普遍使用的彩色电视用红色荧光粉是Y2O2S∶Eu3 。因其色纯度高,色彩不失真,亮度-电流饱和特性好等优异的性能,一直为人们所关注,并对其进行了许多研究[1￣4]。但Y2O2S∶E u3 价格较贵。为了满足市场对红粉的需求日益增长的趋势,有必要研究、开发价廉质优的其他稀土硫氧化物荧光材料。最近,宋春燕等[5]报道了橙红色发光材料La2O2S∶Eu3 的合成及其余辉现象。这些硫氧化物荧光粉均采用高温固相反应——硫熔法合成,主要原料为稀土氧化物、N a2CO3和硫磺。与高温固相合成法相比,微波辐射加热法不仅耗时短,而且合成条件简单,荧光粉粒度…     

同轴静电纺丝技术制备Y_2O_3:Eu~(3+)@SiO_2豆角状纳米电缆与表征

采用同轴静电纺丝技术,以氧化钇、氧化铕、正硅酸乙酯(C8H20O4Si)、无水乙醇、PVP和DMF为原料,成功制备出大量的Y2O3:Eu3+@SiO2豆角状纳米电缆.用TG-DTA,XRD,SEM,TEM和荧光光谱等分析技术对样品进行了系统地表征.结果表明,得到的产物为Y2O3:Eu3+@SiO2豆角状纳米电缆,以无定型SiO2为壳层,晶态Y2O3:Eu3+球为芯,电缆直径约为200nm,内部球平均直径约150nm,壳层厚度约为25nm,电缆长度300μm.纳米电缆内部为球状结构,沿着纤维长度方向有序排列,形貌均一.Y2O3:Eu3+@SiO2豆角状纳米电缆在246nm紫外光激发下,发射出Eu3+离子特征的波长为614nm的明亮红光.对其形成机理进行了初步讨论.     

卵磷脂纳米反应器中Eu2O3纳米粒子的合成及机理探讨

利用大豆卵磷脂在水中自发形成的囊泡作为纳米反应器得到含有磷脂的铕前驱体,经灼烧得到Eu2O3 纳米粒子.对该含磷脂的铕前驱体进行荧光光谱分析、傅立叶变换红外分析(FTIR)以及热分析(TG-DTA),结果显示,在纳米粒子的制备过程中Eu3+ 与大豆卵磷脂络合形成了Eu-O-P键;该前驱体经720℃高温灼烧后得到的纳米样品经XRD分析发现EuPO4 相的存在,并确认了Eu3+ 通过磷氧键与卵磷脂的亲水头部相结合.经过以上分析,对该系统中纳米粒子的形成机理有了初步的认识.     

Y_2O_3∶Eu~(3+)纳米线阵列的制备与表征

Y2 O3∶ 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 1 0 0 %而广泛用于荧光灯和投影电视等方面 .近年来 ,Y2 O3∶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 Y2 O3∶ 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 Y2 O3∶ 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 61 1 nm处的红色发光峰出现了宽化 .HeYu等 [6 ] 采用水热法及退火处理制备出…     

纳米(Y0.95Eu0.05)2O3及其SiO2气凝胶介孔组装体的制备与光致发光

采用尿素溶胶法合成(Y0.95Eu0.05)2O3纳米粉,用超临界干燥技术制备了n-(Y0.95Eu0.05)2O3/SiO2气凝胶介孔组装体。结果表明,当Y3+∶　Eu3+=20∶　1,均相反应时间为4 h,且经680℃、 4 h灼烧热处理后得到的n-(Y0.95Eu0.05)2O3中, 光致发光强度最大（发光峰位于612 nm),以Si与 2Y摩尔比为1∶　7的n-(Y0.95Eu0.05)2O3/SiO2气凝胶介孔组装体,经同样条件热处理后,光致发光强度达不到n-(Y0.95Eu0.05)2O3的红光发射强度,而且峰位出现红移（发光峰在616 nm）。对产生上述发光强度减弱和峰位红移现象进行讨论。     

Vacuum Ultraviolet Excited Photoluminescence Properties of Y2O2S：Eu^3＋,Bi^3＋ Phosphor

As an Hg-free lamp using phosphor, the Bi3+ and Eu3+ co-doped Y2O2S phosphors were prepared and their luminescence properties under vacuum ultraviolet(VUV) excitation were investigated. The VUV photoluminescent 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 med...     

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.     

Preparation and surface effect analysis of trivalent europium-doped nanocrystalline La2O2S

La2O2S:Eu3+ nanocrystals (NCs) with a mean size of 18 nm are prepared by gel thermolysis. The morphology of the particles is hexagonal. The surface Eu3+ ions are first detected by time-resolved spectra in the 5D0 --> 7F1 region. Because the symmetry of the sites occupied by surface Eu3+ ions is lower, the 5D0 --> 7F1(E) line, which is doubly degenerate in the bulk crystal, is split, and the fluorescence lifetime becomes shorter. The results of the laser-selective excitation indicate that the degradation of the site symmetry of Eu3+ seems to be abrupt, which means the as-synthesized La2O2S:Eu3+ NCs might be of the La2O2S/La2O(2-x)S(1+x)core-shell structure and the shell are not in a disordered state but a rather pure one.     

Optical properties of nanocrystalline Y2O3:Eu depending on its odd structure

The structure of nanocrystalline Y2O3:Eu prepared by a combustion reaction was analyzed by XRD and high-resolution electron microscopy. Compared with a large-scale particles, 5-nm Y2O3:Eu particles presented as distorted crystallite and rough surfaces. Luminescent and absorption properties of nano-Y2O3:Eu showed remarkably particle size effects. At Y2O3:Eu particle sizes smaller than 10 nm some new results were observed: (a) a red shift of the charge-transfer-state absorption; (b) new emission bands of Eu3+ in the 5D0 --> 7F2 region; (c) luminescent decay of energy level 5D0 of Eu3+ turning to a two-step exponential; and (d) a pronounced increase in quenching concentration and much lower phonon density compared with those of the bulk material. All these phenomena can be attributed to the effect of the softened lattice and surface state of the nanomaterial. The latter was confirmed by stronger excitation by the host absorption after the surface modification.     

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.     

Ag@SiO2@Y2O3:RE3+（RE=Eu,Tb）核壳结构发光材料的制备与性能

采用均相沉淀法制备了Ag@SiO2@(Y,RE)(OH)CO3.H2O(RE=Eu,Tb)核壳结构微球,经过700℃焙烧后成功制备出Ag@SiO2@Y2O3:RE3+(RE=Eu,Tb)核壳结构发光材料。XRD谱图表明Ag核具有结晶良好的面心立方结构;SiO2层为无定型;Y2O3层为立方晶系。FTIR谱图表明核壳之间以化学键相结合。TEM照片表明合成了核壳结构的表面光滑的复合微球,分散良好,大小均匀,Ag核的粒径分布为50±20 nm;SiO2层的厚度为20～30 nm;Y2O3:RE3+(RE=Eu,Tb)层厚度约为125 nm。电子衍射图像表明Ag@SiO2@Y2O3:RE3+(RE=Eu,Tb)为多晶结构。UV-Vis光谱表明表面包覆使Ag离子的等离子体共振吸收峰发生了红移。荧光光谱表明Ag@SiO2@Y2O3:Eu3+具有Eu3+的特征红光发射,Ag@SiO2@Y2O3:Tb3+具有Tb3+的特征绿光发射,但是发光强度均比纯的Y2O3:RE3+有所减弱,说明贵金属的引入对稀土Y2O3:RE3+(RE=Eu,Tb)的发光起到了荧光猝灭的作用。     

铽含量对硫氧化钇纳米发光材料荧光性能的影响

用燃烧法制备了不同Tb3+掺杂量的Y2O2S:Tb3+纳米发光材料,同时用高温固相法制备了不同Tb3+掺杂量的Y2O2S:Tb3+体相材料,X射线晶体衍射结果表明,制备的纳米材料和体相材料均为单一的Y2O2S相.由Debye-Scherre公式估算得到纳米颗粒的平均粒径大约为10 nm.讨论了纳米材料和体相材料Y2O2S:Tb3+中Tb3+的掺杂浓度对荧光性能的影响.激发光谱表明纳米材料的基质吸收带与体相材料相比向高能端移动了6nm,应用久保理论对此进行了定性的解释.     

水热法制备具有光滑表面的球形Y2O3∶Eu3+发光材料

The spherical Y₂O₃∶Eu³⁺ luminescent particles with size of 0.5～3 μm and smooth surface were synthesized by hydrothermal method. The resulted Y₂O₃∶Eu³⁺ precursors and the calcined particles were characterized by differential thermal analysis (DTA) and thermogravimetric (TG) analysis, X-ray diffraction (XRD), Fourier-transform IR spectroscopy (FTIR), scanning electron microscopy (SEM) and photoluminescence spectra (PL). FTIR, TG-DTA, XRD measurements show that the precursors are crystal with hydroxyl and carbonate group, and the pure cubic yttria is obtained after annealing above 700 ℃. The SEM images indicate that the Y₂O₃∶Eu³⁺ particles are in spherical shape and with smooth surface. PL analysis shows that the particles present characteristic red emission of Eu³⁺.     

空气中合成M2B4O7:Eu3+(M=Na,K)荧光体及其性质表征

以M2B4O7(M=Na,K)为基质,在空气中掺杂稀土元素Eu3+得到了Na2B4O7:Eu3+和K2B4O7:Eu3+荧光体.探讨了体系的烧结条件和荧光性质,分析了晶体的结构.结果表明,虽然两种体系的最佳合成条件不同,但是体系中都同时存在[BO4]和[BO3]结构;稀土离子Eu3+的发光以电偶极跃迁5D0-7F2为主,处于非中心对称的格位上,并且可以很好地存在于基质中,Na2B4O7:Eu3+具有较强的发光强度.