Fabrication of super-hydrophobic nano-sized copper films by electroless plating

Super-hydrophobic nano-sized copper films were fabricated on smooth glass substrates by an improved electroless plating technology. The copper film deposited for 1 min showed extremely high hydrophobicity with a water contact angle of 138.0^o and super-hydrophobicity with a water contact angle of 152.4^o when it was modified with 1-octadecanethiol (CH3-(CH2)17-SH). Such super-hydrophobicity is attributed to the combined roles of the surface hierarchical structure consisting of the micro-sized island-shaped agglomerates that are composed of the nano-sized copper nodules and the low surface energy formed through the chemical modification.     

Molten salt synthesis and photoluminescence properties of novel red emitting phosphors Ba5(VO4)3Cl:Eu3+,K+

A series of Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors have been synthesized by the molten salt synthesis method. The crystalline structure, morphology, photoluminescence properties and lifetimes were characterized using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and photoluminescence spectroscopy, respectively. XRD indicates that the Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors are synthesized successfully via molten salt method. SEM image demonstrates that the obtained phosphors have hexagonal polyhedron morphology. The photoluminescence spectra reveal that the as-prepared phosphors exhibit a bright red emission under the excitation of blue or near ultraviolet light. The concentration quenching was also investigated, and the dipole–dipole interaction is responsible for the concentration quenching of fluorescence emission of Eu³⁺ ions in Ba₅(VO₄)₃Cl phosphor. The present work suggests that the Ba₅(VO₄)₃Cl:Eu³⁺,K⁺ phosphors would be a potential candidate for light emitting devices.     

纳米GaOOH及GaOOH:Eu~(3+)荧光粉的水热法合成及光学性能研究

采用水热法添加醋酸钠制备了纳米羟基氧化镓(GaOOH)粉体和纳米GaOOH:Eu3+荧光粉,使用透射电镜(TEM)、扫描电镜(SEM)、X射线衍射仪(XRD)和荧光分光光度计对产物的形貌、晶相和发光性质进行了检测,结果发现醋酸钠(NaAc)在控制晶体粒径和形貌方面起到了非常重要的作用。在140℃水热条件下,未添加醋酸钠下得到的是纺锤体GaOOH,添加醋酸钠得到的是立方体块状GaOOH,在170℃水热条件下,添加醋酸钠得到的是纳米GaOOH粉体,平均粒径约为5nm,并简单讨论了不同形貌GaOOH的生长机制。比较不同温度添加醋酸钠制备的GaOOH:Eu3+荧光粉的发光性质发现,170℃得到的GaOOH:Eu3+发光强度140℃的样品,不同掺杂浓度发光性能结果表明Eu3+浓度为10%(摩尔分数)发光强度最高,是已报道的掺杂浓度的4倍,在掺杂浓度为15%(摩尔分数)观察到了浓度猝灭现象。     

连续含铝SiC自由膜的制备与发光特性研究

通过自制喷膜装置对聚铝碳硅烷(PACS)进行脱泡处理、熔融纺膜,并对其进行氧化交联、高温预烧及高温裂解终烧可制得连续含铝SiC自由薄膜.用扫描电镜(SEM)分析薄膜的形貌,通过红外光谱(FT-IR)分析氧化交联后薄膜的结构变化,通过电子探针(EPMA)、拉曼光谱(Raman)、X射线衍射(XRD)与场发射高分辨透射电子显微镜(HRTEM)对薄膜进行成分及微观结构分析,采用光致发光谱(PL)对薄膜的光学带隙和发光特性进行了研究.结果表明,熔融纺膜法与PACS先驱体法相结合可制得均匀、致密的耐高温连续舍铝SiC自由薄膜,室温下表现出了320～440nm宽谱带发光,其发光峰可分别归因于α-SiC和C簇,且随着烧结温度的提高,发光强度增大.     

Radioluminescence and photoluminescence of hafnia-based Eu-doped phosphors

Crystal structures of hafnia are discussed and it is shown that addition of about 7 at.% of Lu to the HfO₂ host lattice enforces the mixed composition to crystallize in cubic structure even at room temperature. Without Lu HfO₂ crystallizes in monoclinic structure. Luminescence and luminescence excitation spectra of Hf_0.93Lu_0.07O_1.965 are presented and discussed for powders prepared at different temperatures (600–1000 °C) and with different content of Eu. It is shown that decay of the 595.4 nm luminescence is longer (2.5 ms) than the 610 nm (1.6 ms). Radioluminescence efficiency of the cubic Hf_0.93Lu_0.07O_1.965 is low and does not exceed 10% of the commercial Gd₂O₂S:Eu.     

磁控溅射制备ZnO:Eu薄膜发光性能研究

采用射频磁控溅射法在蓝宝石基片上制备ZnO:Eu薄膜,通过X射线衍射仪和荧光分光光度计等测试其晶体结构和发光特性,分析退火对薄膜晶体结构和发光特性的影响.结果表明,ZnO:Eu薄膜为C轴择优生长的多晶薄膜,实现ZnO基质中掺杂Eu3+;退火样品结晶质量较好,有助于ZnO:Eu薄膜中Eu3+的5D0-7F2的能级跃迁发光;高于ZnO带隙的高能激发(间接激发)和Eu3+的7F0-5L6和7F3-5D2能级间的低能共振激发(直接激发)都能观察到Eu3+的5D0-7F2能级跃迁的特征发光(618nm);间接激发时存在ZnO基质与Eu3之间发生能量传递.     

Combustion synthesis and photoluminescence study of UV emitting LaBaB<Subscript>9</Subscript>O<Subscript>16</Subscript> phosphors

The borate phosphor LaBaB₉O₁₆ doped with Ce³⁺ ion intentionally and successfully synthesized using solution combustion rout using metal nitrates as precursors and urea as fuel. The phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy and photoluminescence spectroscopies. The XRD patterns of the phosphor confirmed the successful crystallization of LaBaB₉O₁₆. The average crystallite size calculated using the Debye Scherer equation. The PL excitation spectra of LaBaB₉O₁₆ exhibited broad spectra peaking at 275 nm. Upon excitation with ultraviolet (UV) radiation at 274 nm the phosphor exhibited a broad band UV emission peaking at a wavelength of 335 nm corresponding to the 4f⁰5d¹??4f¹ transition of the Ce³⁺ ion. Moreover the influence of concentration of Ce³⁺ ion on luminescence properties has also been studied. Optimum concentration of Ce³⁺ ions in the prepared phosphor was found to be 0.05 mol. For this concentration the critical distance R₀ was calculated to be 22.04 Å. Finally, the Stokes shift for the synthesized phosphor was calculated to be 6512 cm^??1 using corresponding excitation and emission.     

溶液缩聚法制备聚酰亚胺绝缘膜及性能研究

以联苯四酸二酐(BPDA)和4,4’-二氨基二苯醚(ODA)为单体原料,利用溶液缩聚法制备聚酰亚胺(PI)绝缘膜,采用XRD、SEM、FT-IR对不同热亚胺化温度合成的PI薄膜结构和表面形貌进行了表征,利用超高阻微电流测试仪测试了热亚胺化温度和粉体含量对PI绝缘膜击穿场强的影响。结果表明,在真空度为1.0×10-2Pa条件下,300℃热亚胺化1h,聚酰亚胺酸(PAA)薄膜完全被热亚胺化,制备的PI绝缘膜内部结构致密;当BPDA和ODA的粉体含量为5%时,PI绝缘膜击穿场强高达2.15MV/cm,表明PI薄膜具有良好的电学性能。     

Chemical and photoluminescence analyses of new carbon-based boron oxynitride phosphors

Analyses of newly developed carbon-based boron oxynitride phosphors using an electron energy-loss spectrometer and a spectroflurophotometer were carried out. The results showed that the prepared phosphor powder has covalently bonded boron, nitrogen, and oxygen atoms with a soft carbon framework. Photoluminescence characterization revealed that the resultant phosphor has a direct bandgap transition with defect broadened band edges, resulting in a high quantum efficiency, because the atomic distances of the phosphor are smaller than those of conventional carbon-based boron nitride compounds, which have an indirect bandgap transition and a low quantum efficiency. The atomic distances of the phosphor are smaller owing to the presence of oxygen atoms, which have a higher electron affinity and a smaller covalent bond radius compared with boron, carbon and nitrogen.     

Fabrication and photoluminescence of thin films of lanthanide–polyoxometalates grafted on colloid silica sphere

In this paper, two lanthanide–polyoxometalates Na₉LnW₁₀O₃₆ (Ln=Eu, Dy, LnW₁₀) were grafted on 400 nm amine-functionalized spherical Stöber silica. The monolayer thin films of hybrid particles were fabricated on quartz by spin-coating method. The hybrid particles and thin films obtained were characterized by IR, UV–vis spectra, scanning electron microscopy, transmission electron microscope and luminescent spectra, respectively. The hybrid particles show strong luminescence which could be seen by naked eyes. The excitation spectra of hybrid particles and thin films show both abroad ligand to metal charge band and the excitation lines of rare earth ions. The transition ⁵D₀→⁷F₀ could be seen in the emission of hybrid EuW₁₀/SiO₂ spheres and thin films, which could not be found in spectrum of EuW₁₀ solid. It is noticed that the intensity ratio of red (⁵D₀→⁷F₂) to orange (⁵D₀→⁷F₁) of Eu³⁺ and the yellow to blue (⁴F_9/2→⁶H_13/2: ⁴F_9/2→⁶H_15/2) of Dy³⁺ in LnW₁₀/SiO₂ particles and thin films are quite different from those of LnW₁₀ solids. The different shapes and ratios between characteristic emissions of hybrid particles and thin films indicated the various symmetry of sites occupied by Ln³⁺ ions.     

Combustion synthesis of borate phosphors

A fast and simple method of preparation, based on the combustion synthesis, is described for the synthesis of borate based PL phosphors which can be used for commercial lamp applications. Phosphors with various structures, incorporating different activators could be successfully prepared. PL intensities of (Gd_0.6Ce_0.2Tb_0.2)MgB₅O₁₀, SrB₄O₇:Eu²⁺ and La_0.88Gd_0.1Bi_0.02B₃O₆ were found to be comparable with those of the corresponding commercial phosphors.     

Combustion synthesis of borate phosphors

A fast and simple method of preparation, based on the combustion synthesis, is described for the synthesis of borate based PL phosphors which can be used for commercial lamp applications. Phosphors with various structures, incorporating different activators could be successfully prepared. PL intensities of (Gd_0.6Ce_0.2Tb_0.2)MgB₅O₁₀, SrB₄O₇:Eu²⁺ and La_0.88Gd_0.1Bi_0.02B₃O₆ were found to be comparable with those of the corresponding commercial phosphors.     

一种P掺杂ZnO纳米梳的制备及其光致发光性能研究

采用化学气相沉积(CVD)方法制备了P掺杂ZnO纳米梳,扫描电子显微镜(SEM)结果显示,纳米梳状产物均匀分布在Si衬底上。P掺杂ZnO纳米梳为高度结晶的六方纤锌矿结构,ZnO中P的掺杂含量约为2%(原子分数)。室温光致发光(PL)光谱表明,P掺杂ZnO纳米梳在样品不同区域的发光性能略有不同,但是均出现3个发光峰:紫外、绿光和近红外发光峰。同时PL结果也表明样品的整体结晶质量比较好。     

Synthesis and calcination temperature dependent photoluminescence properties of novel bromosilicate phosphors

Novel Eu²⁺-doped bromosilicate phosphors, (CaO-CaBr₂-SiO₂):0.03Eu²⁺, were prepared by the traditional solid-state method under a different calcination temperature. The as-prepared (CaO-CaBr₂-SiO₂):0.03Eu²⁺ phosphors obtained under various reaction temperatures all indicated a broad excitation in the near ultraviolet region (350-450 nm). The phosphor system exhibits bluish-green light with a peak wavelength at 498 nm when the calcination temperature is below 800 °C, while it shows a strong blue emission light with a peak wavelength at 474 nm as the calcination temperature is above 800 °C, and it also gives an interesting greenish-yellow long-lasting phosphorescence with a peak wavelength at 540 nm in the dark.     

Enhanced photoluminescence decay processes of doped CaS phosphors at low temperature

CaS phosphor samples singly doped with Mn impurity and doubly doped with Mn and X (X=?Fe, Co and Ni) have been synthesized using a flux method. Crystal structure and phase identification of doped CaS phosphors have been carried out by X-ray diffraction (XRD) studies. A pulse excitation method has been employed to study the optical parameters of the doped phosphors. Excited state lifetime measurements at liquid nitrogen temperature were carried out with a pulsed UV laser (nitrogen laser) as the excitation source has a short pulse width (10?ns) and high peak power (200?kW per pulse). The results have been compared with room temperature lifetime studies. Enhancement in photoluminescence intensity and lifetime shortening in these synthesized doped phosphors is reported at low temperature. The lifetime values have been found to be in the microsecond time domain for CaS:Mn phosphors while on addition of a quencher impurity Ni to CaS:Mn phosphors, the lifetime values reduce to the nanosecond time domain at 77?K temperature. A thermally activated carrier transfer model has been proposed to explain the observed abnormal temperature behaviour of emission from CaS:Mn, X-doped phosphors.     

Microwave synthesis of nano-sized barium titanate

Nano-sized barium titanate powders have been synthesized by microwave processing at 2.45 GHz. Using barium titanyl oxalate (BTO) as a precursor, microwave processing was carried out by heating the precursor to a temperature between 600 °C and 750 °C with different heating rates from 10 °C/min to 20 °C/min without isothermal holding. X-ray diffraction analysis indicates that the decomposed product at 680 °C was pure cubic BaTiO₃. The BET specific surface area of barium titanate powder, after microwave heating to 680 °C, was 14.2 ± 0.5 m²/g, corresponding to an average particle size of 70 nm. This particle size was confirmed by the scanning electron microscopy (SEM). Parallel study shows that the conventional heating in a regular resistance furnace using a similar heating schedule did not result in complete conversion of BTO. This study shows that the microwave processing significantly accelerated the decomposition of barium titanyl oxalate and reduced the temperature of barium titanate nano-powder formation, resulting in nano-sized pure cubic barium titanate powder.     

Fabrication of silica nanocoatings on ZnS-type phosphors via a sol–gel route using cetyltrimethylammonium chloride dispersant

In order to apply ZnS-type phosphors in field emission displays (FEDs), their poor ageing performance, resulting from their surface oxidation at high current densities, should be improved. In this study, the green emitting ZnS:Ag,Cl phosphors are covered with uniform and continuous SiO₂ coatings via a sol–gel route, which is expected to inhibit their surface oxidation. During the gelation process, cetyltrimethylammonium chloride (CTAC), a cationic surfactant, is added to increase the dispersibility of phosphors in suspension. Furthermore, the addition of CTAC promotes uniform distribution of charges on the whole phosphor surfaces, thus benefit the formation of continuous and uniform coatings.     

Shape controlled synthesis,characterization and photoluminescence properties of YVO4:Dy3+/Eu3+ phosphors

Raisin-like, grape-like and box-like nanocrystalline samples of YVO₄:Dy³⁺(2 at.wt%)/Eu³⁺(4 at.wt%) have been synthesized by different preparative routes. The raisin-like nanocrystalline sample has been synthesised by a facile hydrothermal process, whereas a surfactant-assisted synthesis led to the formation of grape-like and box-like nanocrystalline samples, under different reaction conditions. The resulting products were characterised by XRD, TEM, FTIR and photoluminescence spectroscopy. One significant outcome of the photoluminescence study involved a detailed observation of the variations in the relative intensity of the ⁵D₀–⁷F₂ transition with respect to the ⁵D₀–⁷F₁ transition of Eu³⁺ in YVO₄:Eu³⁺, and the relative intensity of ⁴F_9/2–⁶H_13/2 transition with respect to the ⁴F_9/2–⁶H_15/2 transition of Dy³⁺ inYVO₄:Dy³⁺. The observations in either case were subsequently explained on the basis of change in the local symmetry of the dopant ion, due to the change in the host morphology. The presented results strongly indicate that the local environment around the dopant ion changes with the change in the host morphology, which in turn influences the chromaticity of the prepared phosphors (both YVO₄:Eu³⁺ and YVO₄:Dy³⁺).     

大功率白光发光二极管光源的制作

采用GaN基蓝色发光芯片为激发源,结合黄色硅酸盐系列荧光粉封装成大功率白光发光二极管(W-LEDs).利用24颗大功率5W白光发光二极管制作了两种不同连接方式的W-LEDs路灯:2并12串,和4并6串.设计了相应的驱动电路,对这两种不同连接方式的大功率W-LEDs路灯的光电特性及其在照明光源中的应用条件作了深入地研究和对比,测试了它们的伏安特性,发光效率以及功效,结果表明2并12串连接方式的W-LEDs路灯具有更加稳定的伏安特性,更高的照度以及更高的功效.与高压钠灯和荧光灯的特性相比较,W-LEDs路灯作为绿色环保光源灯,具有更高的显色指数,更加环保,节能.