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。     

Lu2O3: Yb3+, Tm3+纳米晶的水热法合成和上转换发光性能研究

采用水热法制备了Yb3+和Tm3+共掺杂的Lu2O3纳米晶。研究了前驱体溶液pH对纳米晶的结构、形貌和上转换发光性能的影响。实验结果表明:制备出的纳米晶具有纯的Lu2O3相,结晶性较好。在980nm半导体激光器激发下,样品发射出蓝光和红光,其发光的中心波长分别位于490和653nm。当前驱体溶液pH为9时,Lu2O3:2%Yb3+,0.2%Tm3+纳米晶上转换发光强度最强,这是因为Lu2O3:2%Yb3+,0.2%Tm3+纳米晶的尺寸最大,其表面吸附的OH-基团最少。发射强度与激发功率的关系表明,蓝光490nm和红光653nm的发光是三光子过程。     

CeO_2:Eu~(3+)纳米晶的溶剂热合成及其发光性能

采用溶剂热技术成功合成晶粒小于100 nm的CeO_2-Eu~(3+)和CeO_2纳米晶,其中CeO_2-Eu~(3+)样品在紫外光激发下发出明亮的橙红色光.用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、傅立叶红外(FT-IR)、紫外漫反射(UV-vis)和光致发光(PL)等手段对产品的结构和性能进行分析和表征.结果表明:CeO_2-Eu~(3+)是纯立方萤石结构的单晶粉末;Eu~(3+)已成功掺入CeO_2晶格中,纳米级的CeO_2-Eu~(3+)和CeO_2的带隙能量分别是2.831和2.925 eV;CeO_2-Eu~(3+)纳米晶在593、612、632 nm处具有较强的发射峰(橙红光),而且较高的退火温度有利于提高样品的晶化度和荧光强度.     

水热法制备YF_3:Eu~(3+)发光纳米束及其性能研究

以PEG为表面活性剂,NaF为氟源,在水热条件下合成出均一的YF3:Eu3+发光纳米束,对其结构进行了表征,并对其形成机制进行了初步探讨。XRD分析表明:样品为结晶良好的正交相YF3。透射电镜照片表明:所得样品为直径200nm,长度约800nm的YF3:Eu3+纳米束,该纳米束由直径30nm,长度70nm的纳米晶自组装而成。SAED显示所得样品为单晶结构。荧光光谱表明:在394nm的紫外光激发下,最强发射峰出现在591nm处,对应于Eu3+的5D0→7F1的磁偶极跃迁,发橙红光。     

燃烧法制备Y2Zr2O7:Tb3+纳米晶及其发光性质研究

以甘氨酸作燃烧剂采用燃烧法制备Y_2Zr_2O_7:Tb~(3+)纳米晶粉末.用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)和荧光分光光度计对Y_2Zr_2O_7:Tb~(3+)纳米晶的相结构、形貌和发光性质进行研究.结果表明:所得到的纳米晶粒度均匀、结晶完好,属于立方萤石结构.发光光谱的测试表明:Tb~(3+)呈现其特征绿色发射,最强峰位于542 nm处.Tb~(3+)的掺杂摩尔浓度在0.5%～6%的范围内,3%为最佳掺杂浓度.     

Yb2O3纳米晶的制备及其若干性能的研究

用溶胶-凝胶法制备了不同粒径的Yb2O3纳米晶。XRD分析表明：所合成的Yb2O3纳米晶属于立方晶系,空间群为Ia3。TEM分析表明：所合成的Yb2O3粒子基本呈球形。计算表明:Yb2O3的平均晶粒度随焙烧温度的升高而增大,而平均晶格畸变随焙烧温度的升高和晶粒度的增大而减小,表明晶粒越大,晶格畸变越大,微晶发育越不完整。溶解性试验表明：Yb2O3晶粒度减小,表面活性增加。FTIR光谱分析表明：纳米Yb2O3比普通的Yb2O3具有更高的表面活性,Yb-O键的吸收强度减弱,有微小的蓝移。     

分散在SiO2中的Y2O3:Eu3+纳米晶的光学性质

采用正硅酸乙酯为SiO2的先驱体,采用Sol-Gel法制备了分散在SiO2基质中的Y2O3Eu3+纳米晶发光材料,研究了材料在不同退火温度下Eu3+稀土离子的光学性质.发射光谱表明随着退火温度的不同,光谱发生了明显变化,并特别地分析了样品在1300℃退火温度下,平均粒径50 nm颗粒样品的发光特性,实验结果表明,在这种发光材料中Eu3+占居4种格位和1种表面态.     

Si衬底Al_2O_3:Eu~(3+)薄膜的溶胶-凝胶法制备及其发光性能

采用溶胶-凝胶法在Si衬底上制备Al2O3:Eu3+薄膜;并采用DTA-TG、XRD、SEM、AFM及光致发光光谱对其进行一系列表征,分析Al2O3:Eu3+薄膜的发光机制,探讨热处理温度和Eu3+掺杂浓度对发光性能的影响规律。结果表明,采用溶胶-凝胶法制备工艺,得到发光强度高的Al2O3:Eu3+薄膜,薄膜的最佳激发波长为265nm,Eu3+的最佳掺杂浓度为10mol%,在265nm光激发下,最强的发射峰出现在617nm附近;采用溶胶-凝胶法制备得到Al2O3:Eu3+薄膜表面致密、平整且无裂纹产生,表面粗糙度约为1.4nm,有利于硅基光电子器件的制备和应用。     

反向共沉淀法制备Y2O3-ZrO2纳米晶

以乙醇为分散剂和保护剂，采用反向化学共沉淀法，制备了Y2O3-ZrO2纳米晶。结果表明：所制备的纳米晶为说办晶系；Y2O3-ZrO2纳米晶呈球形，当焙烧温度为900℃时，粒予粒径约30nm，粒径分布均匀，无明显硬团聚体存在；Y2O3-ZrO2纳米晶为多晶结构：Y2O3-ZrO2的晶化温度为489．19℃；Y2O3-ZrO2纳米晶的相对密度随粒径增大而增大。     

化学共沉淀法制备BaAl_2Si_2O_8:Eu~(2+)荧光粉及其发光特性

采用化学共沉淀法一次煅烧工艺制备BaAl2Si2O8:Eu2+荧光粉。用X射线衍射仪、荧光分光光度计和扫描电镜等对BaAl2Si2O8:Eu2+荧光粉的相结构、发光性能、形貌进行表征。结果表明,化学共沉淀法合成了单相的BaAl2Si2O8:Eu2+,且粒度小,分布均匀,呈类球形。在320nm激发下,其发射主峰位于465nm附近,当Eu2+的掺杂浓度为3.5%,发光强度达到最大值,猝灭浓度有所提高,这主要是由于纳米微粒边界对能量共振传递的阻断和猝灭中心在纳米晶内分布的涨落性引起的。     

TiN薄膜的合成及其性能研究

用电子束蒸发沉积钛和40keV氮离子束轰击交替进行的办法合成了TiN薄膜。用RBS,AES,TEM,XPS,和X射线衍射研究TiN薄膜的组分和结构表明:用离子束增强沉积制备的TiN薄膜主要由TiN相构成;晶粒大小为30—40um,无择优取向;而非离子束轰击沉积的薄膜则是无定形的;用离子束增强沉积制备的TiN薄膜,其氧含量明显小于无离子束轰击薄膜的值;在TiN薄膜和衬底之间存在一个界面混合区,厚度为40um左右。机械性能测试表明,TiN薄膜具有高的显微硬度,低的摩擦系数。     

Synthesis and fluorescence properties of CdTe:Eu~(3+) nanocrystals and core-shell SiO_2-coated CdTe:Eu~(3+) nanospheres

Eu~(3+) doped-CdTe(CdTe:Eu~(3+))nanocrystals were prepared via a facile hydrothermal method,and Eu~(3+) was successfully incorporated into the crystal lattice of CdTe and measured by X-ray powder diffraction(XRD),transmission electron microscopy(TEM),ultraviolet-visible(UV-Vis) absorption spectroscopy and fluorescence emission.The CdTe:Eu~(3+) nanocrystals still have a cubic crystal structure,and the corresponding XRD peaks of CdTe:Eu~(3+)nanocrystals shift to larger angles compared with those of pure CdTe.The CdTe:Eu~(3+) nanocrystals are monodisperse and the particles size is about 2-4 nm.Compared with pure CdTe,the CdTe:Eu~(3+) nanocrystals have larger band gap and thus exhibit blueshift in the emission spectra,which could be accounted for by the energy transfer between Eu~(3+) and CdTe.To enhance the stability and functionality of CdTe:Eu~(3+)nanocrystals,the CdTe:Eu~(3+)nanocrystals were coated with SiO_2 and the core—shell SiO_2-coated CdTe:Eu~(3+)nanocrystals(CdTe:Eu~(3+)@SiO_2) were prepared via microemulsion method.TEM results show that CdTe:Eu~(3+)nanocrystals are uniformly dispersed in the shell,and CdTe:Eu~(3+)@SiO_2 nanospheres are uniformly spherical with an average diameter of about 75 nm.The fluorescence emission of CdTe:Eu~(3+)@SiO_2(567 nm) shows a blueshift compared with that of CdTe:Eu~(3+)nanocrystals(632 nm),possibly because of altered surface properties after SiO_2 coating.CdTe:Eu~(3+)and CdTe:Eu~(3+)@SiO_2 with tunable photoluminescence are potentially useful in fabricating optical and bioimaging devices.     

新型结构Y_2O_3:Eu~(3+)发光材料的合成方法

综述了几种新型结构Y2O3:Eu3+发光材料的研究进展.详细介绍了核壳结构球形SiO2/Y2O3:Eu3+发光材料的合成方法,该方法可以大大降低荧光粉的成本.同时,还介绍了纳米Y2O3:Eu3+颗粒的表面修饰以及一维纳米结构材料的合成技术,并对各种合成方法所得产品的粒径、发光性能做了分析和比较,同时对各种方法的特点进行了归纳和总结.     

FABRICATION AND PROPERTIES OF Al 2O 3 /Ni COMPOSITES

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PREPARATION OF ZnO CERAMIC POWDER BY SOL-GEL METHOD AND ITS VOLTAGE SENSITIVE PROPERTIES

ＰＲＥＰＡＲＡＴＩＯＮＯＦＺｎＯＣＥＲＡＭＩＣＰＯＷＤＥＲＢＹＳＯＬＧＥＬＭＥＴＨＯＤＡＮＤＩＴＳＶＯＬＴＡＧＥＳＥＮＳＩＴＩＶＥＰＲＯＰＥＲＴＩＥＳ①ＣｈｅｎＪｉａｎｘｕｎ,ＺｈａｏＲｕｉｒｏｎｇａｎｄＪｉａｎｇＨａｎｙｉｎｇＩｎｓｔｉｔｕｔｅｏ...     

纳米Cr2O3的制备及其化学复合镀层光催化性研究

采用硬脂酸凝胶法制得Cr2O3纳米晶，用差热-热重(TG-DSC)分析法对制备过程进行了分析。结果表明，560℃时有机物已除去，X射线衍射(XRD)表征所得产物粒径为27nm刚玉型Cr2O3，比表面法(BET)测得比表面为84．3m^2／g。通过化学复合镀的方法固定纳米氧化铬，对不同镀层及纳米Cr2O3粉末降解次甲基蓝进行了研究，结果表明：纳米Cr2O3粉末光催化性最强。而超声波搅拌分散的镀层强于其它镀层。     

YVO_4: Eu~(3+) photoluminescence films with Bi doping

Y0.95-xEu0.05VO4:x Bi3+(x = 0, 0.02, 0.04,0.06, 0.08, and 0.10 mol) six photoluminescence films were deposited on glass substrates by sol–gel spin-coating method. Their morphology and optical property were investigated. The micrographs for the six samples have no change with Bi3→doping. The emission spectra result shows that a dominant red emission peak at 620 nm, which is due to the Eu3+electric dipole transition of5D0→7F2,is observed under excitation wavelengths 254 nm. Furthermore, with the content of Bi3→increasing from 0 to0.08 mol, the emission intensity of samples strengthens and reaches a maximum at x = 0.08 mol, then decreases with the doping content to 0.10 mol.     

Luminescent Properties and Energy Transfer Mechanism of Gd~(3+) and Eu~(2+) Co-doped Phosphate Glasses

The phosphate glasses doped with Eu2+,Gd3+,respectively,and co-doped with Gd3+and Eu2+were prepared by high-temperature melting method.The transmission spectra,the excitation spectra,the emission spectra and the fluorescent decay time were investigated.The energy transfer process between Gd3+and Eu2+was studied.From the excitation spectra and the emission spectra of the phosphate glasses doped with Eu2+,we observed that the emission intensity of Eu2+shows higher for 0.02 mol% Eu2+-doped phosphate glass.According to the excitation spectra and the emission spectra and the fluorescence decay curves,when the concentration of Eu2+was 0.02 mol%,the optimal concentration of Gd3+was 0.3 mol%.Based on Dexter theory,it is shown that the energy transfer between Gd3+and Eu2+was nonradiation energy transfer by analyzing the energy-level diagram.The fluorescence decay curves of Gd3+were expressed by the Inokuti–Hirayama's model and were used to analyze energy transfer mechanism between Gd3+and Eu2+.And the energy transfer efficiency was also calculated.     

Eu~(3+)掺杂ZnO-MgO-La_2O_3-B_2O_3基发光光纤的弹脆塑性

采用高温固相反应法制备了Eu3+掺杂ZnO-MgO-La2O3-B2O3基质的光致发光光纤,通过轴向拉伸试验测量了该光纤的应力-应变曲线。应用弹脆塑性理论研究了屈服面的变化和应力-应变的本构关系,计算了拉伸弹性模量、拉伸强度、拉伸最大负荷、拉伸强度的应变、断裂伸长率和材料的脆性指数。结果表明,该光纤弹性模量高于普通玻璃和大理石,接近于硬铝合金和轧制铝,其拉伸强度和所能承载的负荷都较大。