Yb3+,Tb3+共掺杂Sr2B2O5荧光粉的制备及其下转换发光性能的研究

采用高温固相法合成了Tb³⁺, Yb³⁺共掺杂的Sr₂B₂O₅荧光粉。通过X射线衍射(XRD)和荧光光谱(PL)对样品的物相结构和发光性质进行了表征。XRD结果表明, 合成样品为单斜结构的Sr₂B₂O₅相。分别使用543 nm和980 nm的监测波长, 得到的激发光谱均在354 nm、374 nm处有较强的激发峰, 其中374 nm处最强, 说明Sr₂B₂O₅荧光材料在近紫外光区对太阳光有很强的吸收; 在374 nm( Tb³⁺:⁷F₆→⁵D₃) 紫外光激发下, 观察到Tb³⁺: ⁵D₄→⁷F_J ( J = 6, 5, 4, 3) 可见光区发射光, 并检测到Yb³⁺: ²F_5/2→²F_7/2的近红外发射光。通过研究激发光谱和发射光谱与Yb³⁺掺杂浓度的关系, 发现在单斜晶体Sr₂B₂O₅中, Yb³⁺具有很高的猝灭浓度。     

下转换发光材料对钙钛矿本征性能的影响研究

利用太阳光的近红外和紫外部分实现全光谱响应无疑已成为提高钙钛矿太阳能电池功率转换效率的重要焦点。通过引入光致发光转换层将近红外或紫外光转换为可见光被钙钛矿光活性层利用,已被认为是一种非常有前景的途径。将两种经典的下转换发光材料(红粉和黄粉)引入钙钛矿本征层,采用一步旋涂法制备钙钛矿薄膜。利用缺陷评定高级显微系统、扫描电镜(SEM)、X射线衍射(XRD)、紫外可见吸收及荧光光谱分别探究了下转换发光材料对钙钛矿薄膜表面粗糙度、形貌、结构及光谱性能的影响。结果表明：下转换发光材料能够优化钙钛矿薄膜表面粗糙度、形貌,并未改变钙钛矿结构。紫外可见分光光度计和荧光光谱仪的结果证实了下转换发光材料确实能够拓宽钙钛矿薄膜的光谱响应范围,使整个吸收光谱范围向短波长方向移动,为有效利用全光谱提供了新思路。     

用喷雾热分解法制备Gd2O3-Y2O3-ZrO2电解质材料的性能

用喷雾热分解方法制备了2 mol%Gd2O3-8YSZ的粉末,用激光粒度分析,X射线衍射(XRD),BET法和扫描电子显微镜(SEM)检测粉末和陶瓷体的性能和结构.结果表明,获得的粉末粒径为12.18 μm,晶粒尺寸为100 nm,比表面积为25.09 m2/g.粉末和陶瓷体材为立方结构.陶瓷体的烧结密度大于98%理论密度.在操作的温度高于600℃下的电导率达2×10-3 S/cm.证实Gd2O3-8USZ材料完全适用于作中温固体氧化物燃料电池(SOFC)的电解质.     

Gd2O2S-HoCu2复合磁性蓄冷材料的制备研究

采用粉末冶金方法首次制备了Gd2O2S-HoCu2金属-陶瓷复合性蓄冷材料。结果表明，将Gd2O2S与HoCu2两种磁性蓄冷材料粉末按照一定比例混合，经球磨处理后压制成块，在氩气保护气氛下1100℃保温30min进行真空烧结，可制备成Gd2O2S-HoCu2金属-陶瓷复合磁性蓄冷材料，新型的金属-陶瓷复合磁性蓄冷材料由GOS与HoCu2两相构成，其比热性能良好，作为3～10K温区附近的蓄冷材料使用非常具有实用价值。     

Gd2O2SO4∶Eu3+亚微米棒的水热合成及发光性能

以Gd2O3、Eu2O3、H2SO4和NaOH为实验原料,采用水热法合成了Gd2O2SO4∶Eu3+亚微米棒。XRD和FT-IR分析表明,前驱体Gd2(OH)4SO4·nH2O通过水热合成和随后的热处理(900℃,2h)能转化成纯相Gd2O2SO4。FE-SEM显示,Gd2O2SO4粉体具有边长500～800nm、长度大于10μm的亚微米棒状结构。PL光谱分析表明,在270nm紫外光激发下,Gd2O2SO4∶Eu3+的主发射峰位于618nm,呈现红光发射,归属于Eu3+的5D0→7F2跃迁,其跃迁具有单指数衰减行为,荧光寿命为1.13ms。     

SrAl2O4:Eu2+材料的发光性能研究

制备了发光性能良好的SrAl2O4:Eu^2 材料，对其激光光谱、发射光谱和长余辉曲线进行了测试与分析讨论，结果表明长余辉衰减符合函数L＝ct^a（a＝0.754）形式。讨论SrAl2O4:Eu^2 材料的长余辉机理，指出长余辉应来自陷阱对空穴的俘获与缓慢释放。发现了SrAl2O4:Eu^2 材料的力至发光性能并分析了其可能原因。     

Y2O2S:Er,Yb纳米晶的制备及其上转换和下转换发光

采用共沉淀法,结合固-气硫化工艺制备了平均粒径约40nm的类球形Y2O2S:Er,Yb纳米晶,并对其在980nm红外激发下的上转换和下转换发射进行了较为详细的研究.Er3+的上转换特征发射分别位于530、550和660hm附近.在表面吸附OH-和CO2-3所形成的特殊声子环境下,Er3+的4S3/2→4F9/2和4I11/2→I13/2多声子弛豫显著提高了4F9/2能级的粒子布居,致使纳米晶具有很强的660nm红光发射.并且红绿光荧光分支比会随Yb3+浓度的提高而显著增大.首次报导了Y2O2S纳米晶中Er3+的红外特征发射.源于Er3+离子4I13/2→4O15/2辐射跃迁的较强红外发射,在晶场作用下分化为峰位分别位于1501、1534和1577nm的3个发射峰.由于4I13/2能级是660nm红光发射的主要布居能级之一,该红外发射与红光发射存在明显竞争.但在较高Yb3+掺杂浓度下,高效的Yb3+→Er3+能量传递可有效削弱红外发射的竞争作用.     

SrAl2O4:Eu2+发光材料的合成工艺研究

以碳粉作还原剂,SrCO3、Al2O3、Eu2O3为原料,在还原气氛下采用固相烧结法合成了SrAl2O4:Eu2+发光材料;对合成物进行了X射线粉晶衍射、荧光光谱测定;并初步探讨了Eu2+的含量、制备工艺过程中的焙烧温度、保温时间、冷却方式等因素对合成样品发光性能的影响.     

复合沉淀法制备(Y,Gd)2O3:Eu纳米粉体及其发光性能

报道了一种采用氨水和碳酸氢铵的混合溶液作为复合沉淀剂来制备(Y，Gd)203：Eu发光粉体的新工艺，采用热分析(TG-DTA)、红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等手段对粉体制备过程中的物理化学变化进行了研究．通过X射线激发的发射光谱研究了Eu掺杂浓度和煅烧温度对(Y，Gd)2O3：Eu粉体发光性能的影响．结果表明采用复合沉淀法制备工艺，经过850℃烧2h，可以得到晶粒尺寸为50nm左右，且基本无团聚的(Y，Gd)2O3：Eu粉体，比表面积为23m^2／g，其X射线激发的发光强度较草酸盐沉淀法所得到的相同组分的粉体大大增强．     

Preparation,structure and optical properties of Pr:Gd2O3 phosphor

Pr³⁺-doped Gd₂O₃ phosphor powders were prepared by co-precipitation method. Their structures during heat-treatments were studied by XRD and IR methods. The pH was optimized to be 8 in the co-precipitation process and the hydroxide precursors were transformed into pure phase cubic Gd₂O₃ at 500 °C for 1 h. Optical properties of Pr:Gd₂O₃ phosphor powders were reported. The main emission bands are assigned to ¹D₂ → ³H₄, ³P₀ → ³H₆, ³P₀ → ³F₂ transition of Pr³⁺ under excitation at 255 and 488 nm. The emission intensities increase with increasing sintering temperature. Concentration quenching appears as the Pr³⁺ doping-concentration up to 1 at.%.     

Preparation and the luminescent properties of Tb3+-doped Gd2O3 fluorescent nanofibers via electrospinning

Tb(3+)-doped Gd(2)O(3) (Gd(2)O(3):Tb(3+)) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH(3)COO)(3)·4H(2)O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd(2)O(3) phase. A possible formation mechanism for the nanofibers is proposed on the basis of the experimental results, which reveals that PEO acts as the structure directing template during the whole electrospinning and subsequent calcination process. The luminescent properties of the nanofibers were investigated in detail. The nanofibers exhibit a favorable fluorescent property symbolized by the characteristic green emission (545 nm) resulting from the 5D4-->7F5 transition of Tb(3+). Concentration quenching occurs when the Tb(3+) concentration is 3 at.%, indicating that the Gd(2)O(3):Tb(3+) nanofibers have an optimum luminescent intensity under such a doping concentration.     

Gd_2O_3空心微球的制备及Gd_2O_3/丁基橡胶复合材料低频阻尼性能

以分散聚合法制备的聚苯乙烯(PS)微球作为模板,通过均相沉淀法制备前驱体PS-Gd(OH)CO_3复合微球,高温煅烧后得到Gd_2O_3空心微球,将其与丁基橡胶复合制备低频高阻尼Gd_2O_3/丁基橡胶复合材料。采用FTIR、SEM、TEM分析、TG分析仪、XRD分析和XPS对Gd_2O_3空心微球的形貌与结构组成进行表征。将Gd_2O_3空心微球与粉体分别作为填料加入丁基橡胶中制备Gd_2O_3/丁基橡胶复合材料。结果表明:Gd_2O_3空心微球由立方萤石结构的颗粒组成,外空心直径为0.9μm,壳层厚度约为100nm;添加空心微球的复合材料阻尼性能较好;与纯丁基橡胶相比,Gd_2O_3/丁基橡胶复合材料的低频阻尼性能明显提高。     

Study on luminescent properties of Eu3+ doped Gd2WO6, Gd2W2O9 and Gd2(WO4)3 nanophosphors prepared by co-precipitation

Eu3+ doped Gd2WO6, Gd2W2O9 and Gd2(WO4)3 nanophosphors with different concentrations have been prepared by co-precipitation. XRD (X-ray diffraction) and SEM (scanning electron microscopy) were used to investigate the structure and morphology. The emission spectra, excitation spectra and fluorescence decay curves were measured, and partial J-O parameters and quantum efficiencies of Eu3+ 5D0 energy level were calculated. Furthermore, concentration quenching curves of Eu3+ in different hosts were drawn. The photoluminescent properties of Eu3+ doped Gd2WO6, Gd2W2O9 and Gd2(WO4)3 nanophosphors have been studied. The results indicate that Eu3+ 5D0-7F2 red luminescence can be effectively excited by 395 nm and 465 nm in Gd2WO6 and Gd2W2O9 hosts, similar to the familiar Gd2(WO4)3:Eu. Especially Gd2W2O9:Eu has strong red emission and high quenching concentration, so it has potential applications for trichromatic white LED as red fluorescent materials.     

An efficient green-emitting luminescent material: Tb3+-activated monoclinic Gd2O3

Monoclinic gadolinium oxide activated with Tb³⁺ is an efficient green-emitting phosphor, even for low Tb³⁺ concentrations. Under X-ray excitation its efficiency is about 50% of that of Gd₂O₂S-Tb. The low amount of blue ⁵D₃ emission from Gd₂O₃-Tb is ascribed to the low-energy position of the 4f-5d band (~ 280 nm). The intensity ratio of the Gd³⁺ excitation lines in the photoluminescence excitation spectrum provides information on the location of the quenching sites (probably Tb⁴⁺).     

Preparation and luminescent properties of Cr3+:Al2O3 nano-powders by low-temperature combustion synthesis

Cr³⁺:Al₂O₃ nano-powders were prepared through low-temperature combustion synthesis (LCS) method by using glucose as a dispersion agent for the first time. The Cr³⁺:Al₂O₃ nano-powders samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and luminescence spectrometer. XRD results showed that pure α-Al₂O₃ phase was obtained for the sample fired at 1100 °C for 0.5 h. TEM results indicated that nano-powders were well dispersed. Luminescence spectrum analysis results indicated that the excitation spectrum of Cr³⁺:Al₂O₃ nano-powders consisted of two bands peaking at 462 nm and 579 nm, respectively, and the emission spectrum consisted of two bands peaking at 692 nm and 668 nm, respectively.     

Magnetic and luminescent properties of Fe3O4@Y2O3:Eu3+ nanocomposites

The multifunctional Fe₃O₄@Y₂O₃:Eu³⁺ nanocomposites were prepared by a facile solvothermal method with Fe₃O₄ nanoparticles as the core and europium-doped yttrium oxide (Y₂O₃:Eu³⁺) as the shell. It is shown that Fe₃O₄@Y₂O₃:Eu³⁺ nanocomposites have a strong photoluminescence and special saturation magnetization Ms of 6.1 emu/g at room temperature. The effects of the magnetic field on the luminescence intensities of the nanocomposites are being discussed. The multifunctional nanocomposites with magnetic resonance response and fluorescence probe properties may be useful in biomedical applications, such as cell separation and bioimaging.     

Sr2NaMg2V3O12的合成及发光性研究

采用高温固相法制备了Sr2NaMg2V3O12荧光粉,研究了焙烧温度、保温时间和NH4VO3用量等工艺参数对合成产物发光性能的影响,得出优化的工艺条件为NH4VO3过量1.5%,600℃预烧2h后900℃保温6h。所合成Sr2NaMg2V3O12荧光粉在紫外激发下发淡蓝绿色近白光,荧光光谱分析结果显示其激发峰主要位于波长小于390nm的近紫外和紫外区,发射谱带为400～640nm,发射主峰位于470nm左右,有望成为新型近白光LED荧光粉。     

纳米SiO_2材料的制备及其发光性能研究

采用溶胶-凝胶法制备了纳米SiO2,样品在800℃下煅烧2h。X-射线衍射(XRD)及扫描电子显微镜(SEM)测试结果表明,该材料具有非晶态结构,颗粒尺寸为90~100nm。该样品在紫外灯照射下发出强烈的黄绿色可见光;对样品进行荧光光谱分析表明,该材料可以发射出较强的490nm的蓝绿光和弱的520nm的绿光。     

Preparation, characterization and spectroscopy of Eu3+ in Gd2O3 nanorods

Eu3+:Gd2O3 nanorods were prepared by a hydrothermal method. X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy were used to characterize the resulting samples. Emission and excitation spectra were studied using xenon excited spectroscopic experiments at 10 K. Energy transfer from Gd3+ to Eu3+, from the band gap of the host to Eu3+, and from Eu3+ (S6) to Eu3+ (C2) was observed. The energy levels of Eu3+ at the C2 site of cubic Gd2O3 were experimentally determined according to the fluorescence spectra at 10 K, and fit well with the theoretical values. The standard deviation for the optimal fit was 12.9 cm(-1). The fluorescent lifetime of 5D0 (2.3 ms at 295 K) was unusually longer than that of the bulk counterparts (0.94 ms), indicating a small filling factor (0.55) for the nanorod volume. However the lifetime of 5D1 was much shorter than that of the bulk counterparts, 65 micros at 10 K, 37 micros at 295 K.