离子交换法制备ZrO_2:Eu~(3+)纳米晶及其发光特性

以强碱性阴离子交换树脂为沉淀剂,采用离子交换法制备了ZrO_2:Eu~(3+)纳米晶,通过XRD,TEM,HRTEM和EDS等对晶体的结构、形貌及化学成分进行了表征,利用3D荧光光谱、激发光谱和发射光谱研究了Eu~(3+)在ZrO_2纳米晶中的发光性质。结果表明,焙烧温度在800℃以下所得的ZrO_2:Eu~(3+)纳米晶主要为四方结构,晶粒尺寸约为5—20 nm,随着焙烧温度的升高,样品的晶结构发生了细微变化,从900℃开始出现了少量单斜晶,由ZrO_2:Eu~(3+)的3D荧光光谱确定了其最佳监测波长和发射波长,在394 nm波长光的激发下观察到纳米ZrO_2中Eu~(3+)的590 nm(~5D_0→~7F_1)和606 nm(~5D_0→~7F_2)特征发射谱,随着相结构细微的变化,发射光谱的形状及强度均发生变化,说明ZrO_2:Eu~(3+)纳米晶的发光性质对其结构非常敏感。     

磷酸体系中铈化合物的形貌控制和发光性能

在磷酸体系中,采用水热合成法通过调节PO_4~(3-)/Ce~(3+)摩尔比控制合成了一维CePO_4纳米棒/线,发现了CePO_4到CeO_2的结构和形貌演变.利用X射线衍射、场发射扫描电镜、能谱分析和荧光光谱分析了产物的相结构、晶粒尺寸、形貌及发光性能.结果表明:随PO_4~(3-)/Ce~(3+)摩尔比的降低,CePO_4纳米棒逐渐演变成纳米线,进而在更低的PO_4~(3-)/Ce~(3+)下由CePO_4导向生成CeO_2一维纳米棒.CePO_4纳米棒/线在300～400 nm范围内有较强的宽带发射,是属于Ce~(3+)离子的5d-4f跃迁.CePO_4纳米线的光致发光性能优于纳米棒.     

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.     

In~(3+)掺杂CeO_2的固溶度及其储氧能力

以(CH_2OH)2和H_2O的混合溶液为溶剂,Ce(NO_3)_3?6H_2O和In(NO_3)_3?4.5H_2O分别为Ce和In源,采用溶剂热法在200℃下合成了前驱体,再经500℃焙烧2 h制备了In~(3+)掺杂的CeO_2粉末.通过研究一系列In~(3+)的添加浓度,得出In~(3+)掺杂CeO_2中In~(3+)的固溶度为1%(摩尔分数).In~(3+)掺杂对CeO_2形貌的影响不大,固溶In~(3+)前后的CeO_2颗粒形貌均为层状结构,但当In~(3+)的添加量高于固溶度时,出现了细碎的第二相颗粒.In~(3+)饱和掺杂浓度时CeO_2粉末的比表面积高于未掺杂的CeO_2,达到100 m2/g,当In~(3+)的添加量大于等于3%时比表面积有所下降.In~(3+)添加量对储氧能力的影响为:首先,In~(3+)的引入能够明显降低CeO_2的低温还原峰温度;其次,当In~(3+)的添加量为饱和浓度1%时,CeO_2的低温储氧能力由未掺杂的3.6×10-4mol/g提高到4.4×10-4mol/g;当In~(3+)的浓度大于等于3%时,试样的低温储氧能力先有所下降,随后趋于稳定.不同In~(3+)添加量CeO_2粉末的晶格常数、氧空位浓度、比表面积和低温储氧能力都在1%In~(3+)固溶度的位置出现了转折.低温储氧能力与比表面积和氧空位浓度都有关联,是二者综合作用的结果.     

BaMgSi_2O_6:RE~(3+)(RE=Tb,Ce)的真空紫外光谱特性

研究了MMgSi_2O_6:Tb~(3+) (M=Ca, Sr, Ba)样品的结构、发光特性.MMgSi_2O_6:Tb~(3+) (M=Ca,Sr , Ba)具有硅酸钙镁石结构,基质掺入铽离子后结构没有明显变化.结果表明:MMgSi_2O_6:Tb~(3+) (M=Ca, Sr ,Ba)在168、220和294 nm附近有强烈的吸收峰.在168 nm真空紫外激发下,546 nm是主发射峰.当材料BaMgSi_2O_6:Tb~(3+)中掺杂Ce~(3+)时,BaMgSi_2O_6:Tb~(3+)样品在168 nm真空紫外激发下的发射强度明显下降.     

包覆结构CeO_2/SiO_2复合磨料的合成及其应用

以正硅酸乙酯水解所得的SiO_2微球为内核,采用均匀沉淀法制备具有草莓状包覆结构的CeO_2/SiO_2复合粉体.利用X射线衍射仪、透射电子显微镜、X射线光电子能谱仪(XPS)、动态光散射仪和Zeta电位测定仪等手段,对所制备样品的物相结构、组成、形貌和粒径大小进行表征.将所制备的包覆结构CeO_2/SiO_2复合粉体用于硅晶片热氧化层的化学机械抛光,用原子力显微镜(AFM)观察抛光表面的微观形貌,测量表面粗糙度,并测量材料去除率.结果表明:所制备的CeO_2/SiO_2复合颗粒呈规则球形,平均粒径为150~200 nm,CeO_2纳米颗粒在SiO_2内核表面包覆均匀.CeO_2颗粒的包覆显著地改变复合颗粒表面的电动力学行为,CeO_2/SiO_2复合颗粒的等电点为6.2,且明显地偏向纯CeO_2;CeO_2外壳与SiO_2内核之间形成Si-O-Ce键,两者产生化学键结合;抛光后的硅热氧化层表面在2 μm×2 μm范围内粗糙度为0.281 nm,材料去除率达到454. 6 nm/min.     

纳米金属铜靶材的微结构与性能

采用自悬浮定向流方法制备金属Cu纳米粉体,在25℃和1.0~1.75 GPa的高压下,单向模压成型,制备含量高于95%的高密度纳米金属Cu晶体材料。用透射电镜、X射线衍射谱和场发射扫描电子显微镜对样品的结构进行表征。结果表明:X射线衍射分析的平均晶粒尺寸未退火时为19.9 nm,退火后为30.5 nm(TEM观察约为60 nm),颗粒基本为球形;样品中除了纳米晶粒外,还出现孪晶结构;孪晶是纳米Cu粉在超高压作用下形变的重要特征之一;纳米晶体Cu样品的电阻率在室温下约为1.56×10-7Ω.m,是粗晶Cu在室温下电阻率(0.167×10-7Ω.m)的9.3倍。     

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980 nm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653 nm.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490 nm和红光653 nm的发光是三光子过程.     

ZnAl_2O_4纳米颗粒的制备与光学性能

以硝酸锌和硝酸铝为原料,以CTAB为表面活性剂,通过水热法成功制备了尖晶石型ZnAl_2O_4纳米晶。并利用X射线衍射(XRD)、场发射扫描电镜(FESEM)、高分辨透射电镜(HRTEM)和选区电子衍射(SAED)、X射线能量色散分析谱仪(XEDS)、傅里叶变换红外光谱(FTIR)和紫外可见吸收光谱(UV-vis)等测试技术对样品的晶体结构、化学成分、形貌和光学性能进行表征。实验结果表明:本方法所制备的ZnAl_2O_4为单相的尖晶石结构,晶化程度良好,晶格点阵发生了膨胀;样品形貌为颗粒状结构,颗粒尺寸在20 nm左右,颗粒形状规则且大小均匀,分散性较好。ZnAl_2O_4纳米晶具有较强的紫外吸收能力,UV-vis光谱发现样品的光学带隙减小,可能是由纳米颗粒的表面效应引起的。     

添加剂对CeO_2-ZrO_2-Al_2O_3复合氧化物结构及性能的影响

分别以柠檬酸(CA)、聚乙二醇(PEG)和淀粉(ST)为添加剂,采用共沉淀法制备CeO_2-ZrO_2-Al2O3(CZA)复合氧化物储氧材料,利用XRD、TG/DSC、SEM、N_2吸附-脱附、氧脉冲吸附和程序升温还原等检测方法对材料性能进行表征。XRD结果表明:ST添加剂的样品经1000℃煅烧后产物主要为CeO_2和γ-Al_2O_3,添加CA与PEG的样品为CeO_2-ZrO_2相,并夹带少量γ-Al_2_O3相;经1100℃煅烧后,3种添加剂样品都主要为CeO2-ZrO2晶相。SEM结果表明:CA、ST和PEG添加剂样品经1000℃高温处理后,分别为颗粒状、蜂窝状和多孔网状结构。N_2吸附-脱附结果表明:经600℃热处理后,ST添加剂样品具有最大的比表面积234.95 m~ 2/g和孔容1.589 cm~3/g;经1000℃热处理后,添加PEG样品获得最大的比表面积、孔容和孔径,其值分别为92.50 m~2/g、0.702 cm3/g和29.84 nm,且有最佳的孔分布和吸附-脱附能力。储氧性能OSC和H2-TPR结果表明:PEG添加剂制备的材料具有最好的储氧能力(OSC)和还原性能;1100℃高温下,ST添加剂样品的结构特性与PEG的接近;而CA添加剂样品的吸附能力、储氧性能都相对较低。     

SrAl2O4：Eu^2＋，Dy^3＋长余辉光致发光材料的固相反应法合成与特性

采用高温固相反应法，在还原气氛下制备了掺稀土离子Eu^2 和Dy^3 的铝酸锶长余辉光致发光材料。XRD研究表明，所制备的铝酸盐具备SrAl2O4的晶体结构。SrAl2O4：Eu^2 ，Dy^3 发光材料的发光光谱是中心位于520nm的带状谱，激发峰波长范围位于300nm～500nm，发光余辉可持续12h以上。研究了SrAl2O4：Eu^2 ，Dy^3 发光材料的耐温性和耐水性，结果表明，随热处理温度升高，发光亮度下降；水浸使发光材料与水反应生成水化物，使发光性能下降。     

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。     

Rapid synthesis and properties of color-tunable phosphors SrMoO_4:Eu~(3+),Tb~(3+)

Color-tunable phosphors Sr_(0.94)MoO_4 :xEu~(3+),(0.06-x)Tb~(3+) were synthesized rapidly by microwave radiation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction(XRD) and fluorescence spectrophotometer. The effects of the ratio of Eu~(3+) and Tb~(3+) on the phase structure and luminescent properties of the phosphors were discussed. The results show that Eu~(3+),Tb~(3+)-doped samples can be well indexed to the pure tetragonal scheelitetype SrMoO_4, indicating that Eu~(3+) and Tb~(3+) are effectively doped into the SrMoO_4 host lattices. The as-synthesized SrO 94 MoO_4:xEu~(3+),(0.06-x)Tb~(3+) phosphors have two luminescent centers(Eu~(3+) and Tb~(3+)), which can show red and green emissions under ultraviolet light excitation, respectively. Doping concentration of Eu~(3+) and Tb~(3+) has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu~(3+)and Tb~(3+).     

Preparation of CeO_2 Nanoparticles and Its Application to Ion-selective Electrodes Based on Acetyl Cellulose

Recently, an increasing interest has beenfound in synthesizing nanoscale particles andclusters[l]' The physical and cheAncal proper-ties vary drastically with size and the use of ul-tTafine particles represents a potentially feftilefield fOr materials research[2]. In particular,the preparation and characterization of ceriumoxide nanopowders have attracted much atten-tion over the past few years due to their greatpotential in many fields. It is commonly used inglass, ceramics, fluorescent powd…     

Synthesis of monodispersed ultrafine Bi2S3 nanocrystals

Monodispersed ultrafine Bi₂S₃ nanocrystals of ∼3 nm were synthesized via a facile and mild method, in which thioacetamide and bismuth oleate complex were used as the sulfur and bismuth precursors, respectively. The obtained Bi₂S₃ nanocrystals possessed a high surface area of 305 m² g⁻¹. The nanostructures of Bi₂S₃ nanocrystals were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and selective area electron diffraction (SAED) techniques. The optical property of the Bi₂S₃ nanocrystals was studied by photoluminescence spectroscopy. A remarkable blue shift and a band gap of ∼1.5 eV were observed. The shape of the Bi₂S₃ nanocrystals could be tuned by adjusting the initial Bi/S molar ratio and reaction temperature, respectively. A possible burst nucleation mechanism for this monodispersed ultrafine Bi₂S₃ nanocrystals was proposed.     

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。     

Synthesis and enhanced luminescence properties of double perovskite NaLa_(0.95-x)Y_xEu_(0.05)MgWO_6 phosphors

Double perovskite Na(La,Y)MgWO_6:Eu~(3+)phosphors were obtained by the sol-gel method.X-ray diffractometer(XRD) patterns,scanning electron microscopy(SEM) images and photoluminescence properties were carried out to study the effect of polyethylene glycol(PEG).Enhanced optical properties were obtained by adding 3 wt% PEG under the excitation of 395 nm.Y~(3+)with smaller radius was selected to substitute La~(3+) in this host to decrease the symmetry and further enhance the luminescence properties.With Y~(3+)concentration increasing,Na_2WO_4 and Y_(30)W_8O_(69) phases came up.The emission spectra showed different shapes,and the emission intensity was enhanced by doping Y~(3+).Under the excitation of 395 and 465 nm,the emission intensity reached the maximum.The Commission Internationale de L'Eclairage(CIE)coordinates of the phosphors were on the edge of the CIE diagram,illustrating that this double perovskite phosphor showed good color purity.Above luminescence properties showed that the synthesized phosphors had great potential in solid-state lighting.     

液氮球磨Sm-Fe合金的组织演变

利用低温液氮球磨技术制备了Sm-Fe合金粉体,采用XRD、HRTEM和惰性气脉冲-红外-热导等方法对Sm2Fe17合金粉体在液氮球磨过程中的组织演变进行了研究。结果表明,液氮球磨可加速细化Sm-Fe合金粉体。球磨5 h后,Sm-Fe合金的晶粒尺寸约为10 nm,9 h后晶粒尺寸约为5 nm。Sm-Fe合金中的氮含量随着球磨时间的延长而增加,主轴转速150 r/min球磨9 h后,氮含量达1.62% (质量分数, 下同)。随着球磨时间的延长,Sm2Fe17相向非晶态转变,降低球磨转速可以延缓非晶的形成过程     

Bi_(3.15)Nd_(0.85)Ti_3O_(12)纳米管阵列的制备与微结构表征

采用溶胶凝胶法,在孔径为200 nm的阳极氧化铝模板中制备了Bi_3.15Nd_0.85Ti_3O_(12)纳米管阵列.通过XRD、SEM、TEM、HRTEM、SAED和Raman光谱测试手段对纳米管阵列的物相、微结构和声子振动特性进行了表征.研究表明,所合成BNdT纳米管为钙钛矿相多晶结构,纳米管外径约为200 nm,管壁厚约10 nm,管径和长度与所用AAO模板尺寸一致.Raman光谱分析表明,Nd离子取代了类钙钛矿层中A位的Bi离子.