高发光强度上转换材料Y_2O_3∶Er,Yb纳米晶的制备

将反相乳液合成方法与水热处理方法相结合,获得Y2O3∶Er,Yb纳米晶的前驱体,经过一定温度灼烧,获得了高发光强度的上转换Y2O3∶Er,Yb纳米晶,经水热处理的纳米晶样品具有更好的晶体结构,有利于激发电子在Er离子4F9/2能级上的分布,进而导致红色发射强度极大地提高.     

pH值和尿素浓度对Yb3+/Er3+共掺杂Y2O3微纳米晶的形成及上转换荧光性质的影响

利用均相共沉淀法, 通过调节前驱体溶液的pH值和尿素浓度, 经700 ℃烧结后合成一系列Y₂O₃∶Er³⁺,Yb³⁺上转换微纳米晶颗粒. 用X射线衍射（XRD）、 透射电子显微镜（TEM）、 Fourier变换红外光谱（FITR）和荧光光谱对样品的物相结构、 微观形貌和发光性能进行表征, 并分析上转换机理. 实验结果表明： 前驱体溶液中的pH值对Y₂O₃∶Er³⁺,Yb³⁺粒径影响较大, 随着pH值的升高, 粒径明显增大, 样品在绿色(500～600 nm)和红色(650～700 nm)的上转换荧光强度明显增强, 红绿比逐渐减小; 尿素浓度对Y₂O₃∶Er³⁺,Yb³⁺纳米颗粒的影响较小.     

980 nm激光激发下Yb/Er共掺杂氟化物纳米晶下转换发射特性

用高温热分解法制备摩尔分数为18%的Yb和摩尔分数为2%的Er共掺杂α-NaYF₄, α-NaLuF₄,β-NaYF₄,β-NaLuF₄和LiYF₄氟化物纳米晶, 并用X射线衍射(XRD)、 透射电子显微镜（TEM）和光致发光光谱表征样品的晶体结构、 形貌和发光性能. 结果表明: 所制备的样品均为纯相; 不同的氟化物纳米晶样品尺寸均匀, 粒径为10~15 nm; 在980 nm近红外激光激发下,所制备的氟化物纳米晶在1 550 nm附近均有下转换发射, 其中β-NaLuF₄∶Yb,Er纳米晶在1 550 nm处的发射最强.     

SDS包裹的YF3∶Yb3+/Er3+纳米晶的制备及荧光性质研究

在乙醇和乙二醇的混合溶剂中,用溶剂热法,150℃条件下,反应24h制备了YF3∶Yb3+/Er3+纳米晶(JCPDS号为74-0911),并一步制备出YF3∶Yb3+/Er3+@SDS纳米粒子.激发光源的波长980nm,YF3∶Yb3+/Er3+@SDS纳米晶有强的上转换发光,发射峰的位置为550nm,666nm 和833nm,分别对应Er3+离子的4S3/2→4I15/2,4F9/2→4I15/2和4S3/2-→4I13/2跃迁.     

掺铒氧化钇荧光粉的合成、表征及辐射发光性能

Radioluminescence (RL) behaviour of erbium-doped yttria nanoparticles (Y₂O₃:Er3+ NPs) which were produced by sol–gel method was reported for future scintillator applications. NPs with dopant rates of 1at%, 5at%, 10at% and 20at% Er were produced and calcined at 800°C, and effect of increased calcination temperature (1100°C) on the RL behaviour was also reported. X-ray diffraction (XRD) results showed that all phosphors had the cubic Y₂O₃ bixbyite-type structure. The lattice parameters, crystallite sizes (CS), and lattice strain values were calculated by Cohen-Wagner (C-W) and Williamson-Hall (W-H) methods, respectively. Additionally, the optimum solubility value of the Er3+ dopant ion in the Y₂O₃ host lattice was calculated to be approximately 4at% according to Vegard’s law, which was experimentally obtained from the 5at% Er3+ ion containing solution. Both peak shifts in XRD patterns and X-ray photoelectron spectroscopy (XPS) analyses confirmed that Er3+ dopant ions were successfully incorporated into the Y₂O₃ host structure. High-resolution transmission electron microscopy (HRTEM) results verified the average CS values and agglomerated NPs morphologies were revealed. Scanning electron microscopy (SEM) results showed the neck formation between the particles due to increased calcination temperature. As a result of the RL measurements under a Cu K_α X-ray radiation (wavelength, λ = 0.154 nm) source with 50 kV and 10 mA beam current, it was determined that the highest RL emission belonged to 5at% Er doped sample. In the RL emission spectrum, the emission peaks were observed in the wavelength ranges of 510–575 nm (2H_11/2, 4S_3/2–4I_15/2; green emission) and 645–690 nm (4F_9/2–4I_15/2; red emission). The emission peaks at 581, 583, 587, 593, 601, 611 and 632 nm wavelengths were also detected. It was found that both dopant rate and calcination temperature affected the RL emission intensity. The color shifted from red to green with increasing calcination temperature which was attributed to the increased crystallinity and reduced crystal defects.     

稀土倍半氧化物电子结构和光学性质的第一性原理研究

利用第一性原理密度泛函方法系统计算五种稀土倍半氧化物(R₂O₃,R为Sc、Y、La、Sm、Dy)的电子结构和光学性质。电子结构计算表明,R₂O₃为间接带隙氧化物,其价带与导带电子存在光学跃迁行为。在光学性质方面,根据能带与态密度分析R₂O₃的复介电函数、复折射率、反射率、吸收率和损失函数,结果表明,在8.13～14.87 e V范围内,R₂O₃具备良好的光学吸收与光学反射率,Y₂O₃的反射率更是达到95%以上。Sc₂O₃、Y₂O₃、La₂O₃、Sm₂O₃和Dy₂O₃的静态介电常数分别为5.18、4.44、4.58、3.52和3.50,具备作为栅介质材料的...     

Effects of aluminum and titanium on the microstructure of ODS steels fabricated by hot pressing

Three oxide-dispersion-strengthened (ODS) steels with compositions of Fe-14Cr-2W-0.2V-0.07Ta-0.3Y₂O₃ (wt%, so as the follows) (14Y), Fe-14Cr-2W-0.2V-0.07Ta-1Al-0.3Y₂O₃ (14YAl), and Fe-14Cr-2W-0.2V-0.07Ta-0.3Ti-0.3 Y₂O₃ (14YTi) were fabricated by hot pressing. Transmission electron microscopy (TEM) was used to characterize the microstructures and nanoparticles of these ODS steels. According to the TEM results, 14Y, 14YAl, and 14YTi ODS steels present similar bimodal structures containing both large and small grains. The addition of Al or Ti has no obvious effect on the microstructure of the steels. The spatial and size distribution of the nanoparticles was also analyzed. The results indicate that the average size of nanoparticles in the 14YTi ODS steel is smaller than that in the 14YAl ODS steel. Nanoparticles such as Y₂O₃, Y₃Al₅O₁₂ and YAlO₃, and Y₂Ti₂O₇ were identified in the 14Y, 14YAl, and 14YTi ODS steels, respectively.     

纺锤状磁性碳酸钙复合材料的制备及其表征

为了探索制备磁性碳酸钙复合材料的新途径,以Ca(OH)₂和CO₂为原料,乙二胺四乙酸二钠(EDTA-2Na)为晶型控制剂,通过在高压反应釜中添加Fe₃O₄纳米粒子,碳化制备了分散均匀、形貌为中空纺锤状的磁性碳酸钙复合材料CaCO₃-Fe₃O₄,采用SEM、XRD、VSM、XPS、TEM等表征方法探究了反应温度、EDTA-2Na添加量等对CaCO₃-Fe₃O₄形貌和性能的影响。结果表明：纺锤状磁性CaCO₃-Fe₃O₄的最佳制备条件为反应温度为120℃、Ca(OH)₂的质量分数为2%、EDTA-2Na用量为Ca(OH)₂质量的8%、反应时间为2 h、Fe₃O₄与CaCO₃的物质的量比为1∶10,所制...     

基于内滤效应猝灭NaYF_4:Yb,Er上转换纳米颗粒荧光选择性地检测酸性品红

采用水热法合成了粒径约为10nm的近似球形NaYF_4∶Yb,Er上转换荧光纳米晶.利用所合成的上转换纳米晶为荧光探针,通过荧光的内滤效应,酸性品红能有效地猝灭NaYF_4∶Yb,Er的荧光.基于此,构建了酸性品红检测传感器.实验中对孵化时间和p H等条件进行了优化.在最佳测定条件下,酸性品红浓度在13. 3×10-5～66. 7×10-5mol/L范围内与上转换纳米晶的荧光强度呈现良好的线性关系,方法的检出限为1. 7×10-5mol/L(S/N=3),相对标准偏差为3. 6%.最后,所构建传感器用于实际水样中酸性品红的检测,获得满意的结果.     

复合氧化物Co3O4/Bi2O3对甲苯的光催化作用

采用微乳法制备复合氧化物Co₃O₄/Bi₂O₃纳米粒子， 用TG-DTA， XRD， XPS和FT-IR对其表征， 以甲苯为气相有机污染物研究Co₃O₄/Bi₂O₃的光催化活性. 结果表明， 微乳法制备的Co₃O₄/Bi₂O₃粒子光催化活性优于纯氧化铋； 活性的提高程度与n(Co) ∶n(Bi)有关， 其最佳配比为0.02 ∶1； 光催化活性随焙烧温度升高而增大, 750 ℃焙烧的样品催化活性最好.     

Upconversion luminescence properties of Mn2+-doped NaYF4:Yb/Er nanoparticles

NaYF₄:Yb/Er upconversion nanoparticles doped with Mn²⁺ were synthesized by hydrothermal method. The upconversion photoluminescence measured by 975 nm continuous wave laser indicates that the as-synthesized samples generated green and red color emission with various intensity ratio ranging from 3.25 to 548.35, which is highly correlative to the dopant concentration of Mn²⁺. However, there is no red emission enhancement observed in Cu²⁺-doped NaYF₄:Yb/Er nanoparticles.     

Synthesis and characterization of red-emitting Yb/Ho-CaSiO3 upconversion phosphors

Host material plays an important role in obtaining efficient photon upconversion and downshifting luminescence. Generally, fluoride and oxyfluoride glasses-based materials are used for high-efficiency photon upconversion. However, the poor thermal stability of fluoride glasses and the toxicity of fluorine ions limit their applications. In this report, Yb/Ho-doped CaSiO₃ wollastonite phosphors have been demonstrated as efficient red-emitting upconversion phosphors. The phosphors have been synthesized by microwave hydrothermal process followed by heat treatment at 1050 ?°C in the air environment. 2M phase of the β-wollastonite has been confirmed by X-ray diffraction and Raman spectroscopy while the existence of the Yb and Ho dopants in the CaSiO₃ lattice has been confirmed by X-ray photoelectron spectroscopy. The synthesized samples showed strong red upconversion emission centered at 662 ?nm and near-infrared downshifting emissions at 2016 ?nm upon 980 ?nm excitation. The emissions were found to depend significantly on the Ho concentration. Temporal evolution of the main emission bands was investigated to show that the energy transfer upconversion from Yb to Ho ions was responsible for the efficient upconversion and downshifting phenomenon.     

水热法合成Y2O3 ∶ Yb3+,Er3+上转换材料及发光特性

以Y2O3,Yb2O3和Er2O3为原料,利用水热法制备Y2O3,Yb3+,Er3+纳米上转换材料.通过X射线粉末衍射、扫描电镜和透射电镜对材料的晶型、成分、粒径及表面形貌进行分析.实验结果表明:所得粉体的晶型为立方晶系,晶粒为圆球形,平均粒径为20 nm.在波长为980 nm半导体激光器激发下产生绿色和红色的上转换荧光;改变Yb3+,Er3+的掺杂比例,激发产生的绿光和红光的荧光强度随Yb3+,Er3+掺杂比例的改变而发生变化.     

上转换材料NaYF4∶Er3+,Yb3+纳米晶的制备

采用溶胶 凝胶法合成NaYF₄∶Er³⁺,Yb³⁺纳米晶. 在980 nm红外激光照射下, 肉眼可观察到明亮的上转换发光; X射线粉末衍射（XRD）结果表明, 该纳米晶属于立方晶体结构; 透射电镜（TEM）照片显示, 晶粒为圆球形, 分散性好, 平均尺寸为70 nm, 符合生物标记过程中对材料的要求. 用荧光光谱仪记录了该上转换光谱, 并对发光机理进行了探讨.     

Yb~(3+),Er~(3+)共掺MWO_4(M=Cd,Ba)纳米晶体的制备及发光性能

以CTAB为表面活性剂,采用水热法合成了Yb,Er共掺MWO4(M=Cd,Ba)纳米晶体.采用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱(EDS)和荧光分光光度计等手段对产物的组成、形貌和荧光性质进行了系统表征.结果表明:Yb3+,Er3+掺杂钨酸盐的发光条件随着M种类的不同而有较大的差异,水热合成的CdWO4:Yb3+,Er3+纳米晶体在980 nm激光照射下用肉眼可观察到明显的绿色上转换发光,而BaWO4:Yb3+,Er3+晶体高温煅烧到900℃才能观察到明亮的绿色发光.研究了温度对上转换发光强度的影响,讨论了两种晶体的上转换发光性质.     

上转换材料LiLa(MoO4)2:Yb3+,Er3+(Tm3+)的制备及其光谱性质测定

采用溶胶-凝胶法制备了上转换材料LiLa(MoO4)2:Yb3+,Er3+(Tm3+),并对其进行了X射线衍射分析以及荧光光谱测定.在980 nm红外激光器激发下,LiLa(MoO4)2:Yb3+,Er3+发出波长为530 nm和550 nm的绿色可见光,而LiLa(MoO4)2:Yb3+,Tm3+发出波长为475 nm的蓝色可见光.对Yb3+/Er3+和Yb3+/Tm3+双掺体系的上转换发光机理进行了探讨,其中Er3+发出绿色上转换光的过程为双光子过程,而Tm3+发出蓝色上转换光的过程为三光子过程.     

Ni增强Er在富硅氮化硅薄膜中的光致发光

采用反应磁控溅射技术沉积了掺Er的富硅氮化硅(SRN:Er)薄膜和SRN:Er/Ni3个周期的超晶格,两种薄膜都在1100℃进行退火实验。SRN:Er薄膜的光致发光谱为一个峰位在665～750nm的发光带和一个峰位在1.54μm的发光带,前者来源于SRN薄膜中的纳米硅,后者为Er3+的特征发射。SRN:Er/Ni超晶格的光致发光谱上出现Er3+在520,550和850nm附近的精细结构,并且Er3+在1.54μm的发光有12倍的增强。光谱精细结构的出现证明Er3+的微观环境由于掺Ni而变得有序。与在SRN中相比,在这种有序环境中Er3+的光学活性有明显的增强。拉曼散射光谱测量证明在SRN:Er/Ni超晶格中纳米硅的数目比在SRN:Er薄膜中有一定的增加。因而,Er3+1.54μm发光12倍的增强是Er3+本身光学活性的增强和纳米硅数目的增加共同作用的结果。     

Soft chemical synthesis and luminescence properties of red long-lasting phosphors Y2O2S:Sm3+

Sm³⁺-activated Y₂O₂S red phosphors were prepared by the combustion method and microemulsion method at the first time. X-ray characterization and electron diffraction show that, Y₂O₂S:Sm³⁺, Ti⁴⁺, Mg²⁺ samples prepared by these two methods are pure hexagonal crystals in structure with a trivial change due to dopants. Scanning electron microscopy (SEM) results show that the product presents an almond-like sheet in uniform size. Under the excitation of 269 nm ultraviolet light, Y₂O₂S:Sm³⁺ samples fabricated by these two methods exhibit three main groups of red emission lines located at 564, 604, and 656 nm, respectively, which are attributed to the transitions of 4G_5/2 →6H_5/2, 4G_5/2 →6H_7/2, 4G_5/2 →6H_9/2, respectively. The samples prepared by microemulsion are seven times higher in fluorescent emission intensity and half time longer in afterglow time than that prepared by combustion.     

Effects of Yb^3＋ codoping on visible and near infrared emissions of Er^3＋-Yb^3＋ codoped Al2O3 powders by the sol-gel method

The 0.1 mol% Er^3＋ and 0-2 mol% Yb^3＋ codoped Al2O3 powders were prepared by the sol-gel method, and the phase structure, including only two crystalline types of doped Al2O3 phase, γ-（Al,Er, Yb）2O3 and θ-（Al,Er, Yb）2O3, was detected at the sintering temperature of 1000℃. The visible and near infrared emissions properties depended strongly on the Yb^3＋ codoping, and the corresponding maximal peak intensities centered at about 523, 545, 660 and 1533 nm were obtained respectively for the 0.1 mol% Er^3＋ and 0.5 mol% Yb^3＋ codoped Al2O3 powders, which were composed of θ-（Al,Er,Yb）2O3 and a small amount of γ-（Al,Er, Yb）2O3 phases. The two-photon absorption process was responsible for the visible up-conversion emissions, and the one-photon absorption process was involved in the near infrared emissions of the Er^3＋-yb^3＋ codoped Al2O3 powders.