阳离子铱(Ⅲ)配合物掺杂的SiO_2微粉的制备及在发光二极管中的应用

将硅酸乙酯水解得Si O2溶胶,陈化1 d后掺入15.0wt%阳离子铱(Ⅲ)配合物[Ir(ppy)2(o-phen)][PF6](ppy:2-苯基吡啶;o-phen:1-乙基-2-(4-(5-(4-叔丁基苯基)-1,3,4-噁二唑-2-基)-苯基)-1H-咪唑并[4,5-f][1,10]菲啰啉),45℃恒温3 d后室温放置10 d得干凝胶,再经研磨和150℃干燥8 h制得黄色发光微粉。将所得的发光微粉按6.0、9.0、12.0、15.0、18.0和21.0wt%掺入到环氧树脂中,作为下转换发光材料涂敷在395 nm发射的In Ga N芯片上制备成LED器件。掺入12wt%Si O2微粉的LED发光性能最佳,在40.0 m A正向电流和5 V反向电压下,该LED达到最大发光效率51.9 lm/W,CIE色坐标为(0.42,0.42)。     

单分散无溶剂纳米SiO2流体对环氧树脂的改性

以纳米粒子SiO₂为核、表面活性剂N,N-十二基-N-甲基-N-(3-三甲氧基甲硅烷基丙基)氯化铵(SID3392)为颈状层、聚(乙二醇)4-壬基苯基醚3-磺丙基钾盐(PEGS)为冠状层,制备出了无溶剂纳米SiO₂流体。无溶剂纳米SiO₂流体为牛顿流体,在室温下具有较低的黏度,在26.5 ℃时其黏度为4.3 Pa·s,无溶剂纳米SiO₂流体中SiO₂的含量为13.65wt%。将该无溶剂纳米SiO₂流体加入环氧树脂中,制备了无溶剂纳米SiO₂流体/环氧树脂复合材料。TEM结果表明: 无溶剂纳米SiO₂流体在环氧树脂基体中具有良好的分散性。DSC测试表明: 无溶剂纳米SiO₂流体的加入会略微降低环氧树脂的固化温度。当纳米SiO₂流体加入量为2.5wt%时,复合材料的冲击性能提高了164.7%,玻璃化温度提高了15.4 ℃。断面SEM结果显示无溶剂纳米SiO₂流体能够提高环氧树脂的韧性。     

纳米SiO2改性聚合物水泥基复合材料早期微观结构及性能

利用纳米SiO₂(nano SiO₂)早期可促进聚合物水泥基复合材料水化速率、提升其力学性能、改善其界面过渡区(ITZ)性能及优化其孔隙结构等特点,借助XRD、SEM、EDS、显微硬度(MH)及压汞(MIP)等试验,揭示了nano SiO₂对聚合物水泥基复合材料早期性能影响的微观机制。结果表明:当nano SiO₂掺量为2wt%时,聚合物水泥基复合材料的力学性能最优,3 d和7 d龄期抗压强度分别为57.5 MPa和67.3 MPa,较仅仅掺加聚合物的水泥基复合材料分别提高了12.7%和13.9%;nano SiO₂的掺入改变了聚合物水泥基复合材料水化产物数量及微观形貌。对于ITZ性能,nano SiO₂掺入后,聚合物水泥硬化浆体-骨料的ITZ厚度减小,形貌变得更加致密;ITZ的钙硅比因nano SiO₂的加入变小而其显微硬度变大;此外,nano SiO₂加入后可以进一步填充聚合物水泥基复合材料更加细小的孔隙,使其凝胶孔比例变高,最可几孔径变小,大大优化了聚合物水泥基复合材料的孔隙结构。      

多级孔Co/Al-SiO2催化剂制备及其费-托合成催化性能

多级孔硅铝材料因优异的性能而成为金属催化剂的重要载体。研究采用水热法以硝酸铝为铝源、正硅酸乙酯(TEOS)为硅源合成了Al掺杂SiO₂(Al-SiO₂)的多级孔材料, 然后采用等体积浸渍法负载钴, 制备了具有多级孔结构的 Co/Al-SiO₂催化剂。对Al-SiO₂材料的表征结果表明: 以四丙基氢氧化铵(TPAOH)为结构导向剂, 经80 ℃水热处理可以合成多级孔Al-SiO₂, 呈尺寸在30~40 nm范围的 “蠕虫状”大孔分布形态。将催化剂用于费-托合成反应, 与商业SiO₂负载的钴催化剂相比, Co/Al-SiO₂的CO转化率提高近一倍, CH₄选择性降低19.3wt%, C₂-C₄选择性降低13.3wt%, 汽油段产物(C₅-C₁₂)选择性达到53.3wt%。     

SiO2中空微球改性含硅芳炔树脂及其复合材料的结构与性能

采用SiO₂中空微球对含硅芳炔树脂（PSAC）进行改性,制备了SiO₂/PSAC复合材料,以改善PSAC固化后质脆的缺点,提高PSAC基复合材料的力学性能,拓展PSAC在航空航天领域的应用。对SiO₂/PSAC复合材料和石英纤维布增强SiO₂/PSAC（QF-SiO₂/PSAC）复合材料的结构与性能进行了研究,采用SEM分析SiO₂/PSAC树脂浇铸体和QF-SiO₂/PSAC复合材料断面微观结构,并分析SiO₂的增韧机制。采用DMA和TGA分析了SiO₂/PSAC复合材料耐热性能和热稳定性,虽然SiO₂会导致树脂耐热性能略有下降,但其中空结构使树脂具有优异介电性能。当SiO₂的添加量达2wt%时,SiO₂/PSAC树脂浇铸体弯曲强度达22.3 MPa,失重5%温度为551℃,1 000℃残留率为86.5%;QF-2SiO₂/PSAC复合材料的弯曲强度为298.3 MPa,弯曲模量达31.0 GPa,分别提高了27.5%、59.0%;当SiO₂添加量为5wt%时,QF-5SiO₂/PSAC复合材料的剪切强度提高了16.0%。      

SiO2表面改性对高填充SiO2/聚四氟乙烯复合薄膜性能的影响

选用三种具有不同疏水官能团的硅烷偶联剂,即含苯基的偶联剂1(Ph-1)、含氟基的偶联剂2(F-2)和含环氧丙氧基的偶联剂3(GP-3)对SiO₂进行表面改性,并采用空气辅助干法共混、冷压烧结并车削成膜的方法制备了SiO₂填充量为35wt%、厚度为50 μm的SiO₂/聚四氟乙烯(PTFE)复合薄膜。改性后SiO₂在PTFE中分散均匀。研究了不同含量F-2对SiO₂/PTFE复合薄膜性能的影响,发现当含氟基的硅烷偶联剂F-2用量(与SiO₂质量比)为0.3%时,SiO₂/PTFE复合薄膜的针孔缺陷最少,拉伸强度由9.2 MPa提高至16.2 MPa;在10 GHz下,SiO₂/PTFE复合薄膜的介电常数由2.475降低至2.416,介电损耗由2.66×10?3降低至2.01×10?3,SiO₂/PTFE复合薄膜显示出优异的综合性能。      

SiO2-苯并噁嗪/双马来酰亚胺树脂的固化反应动力学

为改善双马来酰亚胺树脂(BMI)脆性过大、耐热性不足的缺点,以末端含有氨基的纳米SiO₂(SiO₂-NH₂)为原料,通过溶剂法制备出结构中含有SiO₂的苯并噁嗪树脂单体(SiO₂-BOZ),作为改性体系加入到BMI中进行共混,制备出一种耐热性能、韧性良好的新型SiO₂-BOZ/BMI树脂材料,并详细研究了SiO₂-NH₂的添加对BMI固化反应动力学的影响。结果表明,当SiO₂-BOZ添加量达到15.0wt%时,SiO₂-BOZ/BMI树脂复合材料的表观活化能较纯BMI树脂得到了一定程度的降低,SiO₂-BOZ/BMI的弯曲强度达到最大值166.12 MPa,较纯BMI 增加了32.3%,且具有比BMI更好的耐热性能。      

核壳结构SiC/SiO2纳米线的低温合成与表征

以酚醛树脂(PF)作为碳源, 纳米SiO₂为硅源, 在1300℃氩气气氛下通过碳热还原反应, 制备出具有核壳结构的SiC/SiO₂纳米线。采用X射线分析衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨率透射电子显微镜(HRTEM)、拉曼光谱(Raman)对产物的组成、形貌、微观结构等进行了表征。结果表明; SiC/SiO₂纳米线长可达数毫米, 单根SiC/SiO₂纳米线由直径30 nm的β-SiC晶体为内核和厚度约12 nm的无定形SiO₂壳层组成; 室温下SiC/SiO₂纳米线的PL发光峰与β-SiC单晶的发光特征峰相比有蓝移。最后, 讨论了核壳结构SiC/SiO₂纳米线的生成机制。     

纳米SiO2质量分数对胶粘碳纤维增强树脂复合材料板-钢搭接界面黏结性能的影响

胶黏剂力学性能对碳纤维增强树脂复合材料(CFRP)加固钢结构的界面黏结性能影响显著。基于研制的胶黏剂配比,分析了不同纳米SiO₂质量分数对胶黏剂常温固化后基本力学性能及微观结构的影响,制作了31个CFRP板-钢板双搭接试件,对其进行了常温固化后的承载能力、有效黏结长度、传力模式、黏结-滑移本构等试验研究,得出了纳米SiO₂质量分数对CFRP板-钢板搭接试件界面黏结性能的影响规律,并与常用商品胶黏剂进行了比较。研究结果表明:随纳米SiO₂质量分数的增加,胶黏剂应力-应变关系由线性转变为非线性,应变能、断裂伸长率及剪切强度分别最高提升了292.10%、202.88%和133.12%。微观结构分析表明纳米SiO₂的添加使断面粗糙度显著增加,形成了密集的塑性空穴,产生了更多的微裂纹,使胶黏剂的韧性大幅度提高。当纳米SiO₂质量分数从0增至1wt%,搭接试件破坏模式由界面破坏逐渐变为CFRP板层离破坏。掺入纳米SiO₂能显著增加搭接试件的极限承载力(提升256.96%)及界面有效黏结长度(提升3倍),提高CFRP表面的应变及界面剪应力峰值。纳米SiO₂质量分数为0与0.5wt%的搭接试件的黏结-滑移曲线为双线性三角形模型,纳米SiO₂质量分数为1wt%的搭接试件的黏结-滑移曲线为三线性梯形模型,黏结界面韧性大幅提升。CFRP-钢界面承载能力受胶黏剂拉伸强度与断裂伸长率的双重影响,非线性高强度(即具有较高应变能)胶黏剂对应的CFRP-钢搭接接头具有更好的界面性能。      

改性碳纳米管/环氧树脂复合材料的介电性能

实验采用混酸法对碳纳米管(CNTs)表面进行改性,制得羧基化碳纳米管(C-CNTs)。采用溶胶-凝胶法制得SiO₂包覆的C-CNTs (C-CNTs@SiO₂)、TiO₂包覆的C-CNTs (C-CNTs@TiO₂),采用原位聚合法制得聚苯胺包覆的C-CNTs (C-CNTs@ PANI)。以环氧树脂(EP)为基体材料,通过溶液共混法制备出C-CNTs/EP、C-CNTs@SiO₂/EP、C-CNTs@TiO₂/EP和C-CNTs@PANI/EP四种复合材料。研究结果表明:当掺杂相的质量分数均为1 wt%时,四种EP基复合材料的冲击强度相对于未改性的环氧树脂均有不同程度的提高。当掺杂相质量分数为7 wt%时,C-CNTs/EP、C-CNTs@SiO₂/EP、C-CNTs@TiO₂/EP和C-CNTs@PANI/EP四种复合材料的介电常数分别是EP的14.1、7.2、2.5、18.8倍。在实验掺杂量下,C-CNTs@SiO₂/EP和C-CNTs@TiO₂/EP的介电损耗几乎没有变化,C-CNTs@PANI/EP的介电损耗略有增加。当掺杂相质量分数为1 wt%时,C-CNTs@SiO₂/EP和C-CNTs@TiO₂/EP的击穿强度相对于EP明显提高。      

Energy transfer and morphology study of a new iridium based cyclometalated phosphorescent complex

This paper reports synthesis and characterization of a new phosphorescent iridium complex namely iridium (III) bis (2-phenylpyridinato–N, C^2′) picolinate [(ppy)₂Irpic]. For its future use in organic light emitting diodes (OLED), we doped the iridium complex into various host materials and carried out a study of energy transfer process through photoluminescence (PL) and photoluminescence excitation (PLE) measurements onto the blended films with different concentrations of (ppy)₂Irpic. The blended films were casted by the spin coating method, as to make the device fabrication process cheaper. The selected host materials were poly(N-vinylcarbazole) (PVK), poly(9,9-dihexylfluorene) (PDHF) and N,N′-diphenyl-bis(3-methylphenyl) [1,1′-biphenyl]-4,4′-diamine (TPD). The blended films with TPD as a host were made in poly(methyl-methacrylate) (PMMA) matrix. The emission from the host molecule disappears at a particular concentration of (ppy)₂Irpic, which is determined as 5 wt%, 12 wt% and 20 wt% of the host materials for blended PVK, TPD (20% by weight of PMMA) and TPD (10% by weight of PMMA) films, respectively. No energy transfer could be observed for PDHF for the concentration range of 0.1–20 wt%. The energy transfer efficiency and the morphology of the various blends were also studied in order to find out the most appropriate host material for the device applications.     

Polymer Light-Emitting Diode Using a New Electrophosphorescent Cyclometalated Iridium Complex

A new iridium-based cyclometalated complex, namely bis (2-phenylpyridine-C², N') iridium (III) picolinate [(ppy)₂Ir(pic)] is synthesized and investigated as electrophosphorescent dopant in polymer-based organic light-emitting diodes. The photoluminescence emission from this complex is observed at 501 nm, with a shoulder at 526 nm. Poly(N-vinylcarbazole) (PVK) is used as host polymer and single-layer devices of PVK doped with (ppy)₂Ir(pic) complex are fabricated. Photoluminescence (PL) spectra of PVK films doped with different concentration of iridium complex were measured to study the possible energy transfer occurring between PVK to iridium complex. A predominant blue to a completely green shifted emission is observed when the doping concentration was increased from 0% to 5 wt%. Optical and atomic force microscopic images of the doped films indicate a smooth film formation when spin coated with chlorobenzene as a solvent as compared to chloroform. Electroluminescence spectra of ITO/PEDOT:PSS/PVK:(ppy)₂Ir(pic)/Al device resembles that of the PL spectra with emission at 507 nm and Commission Internationale de l'Eclairage (CIE) coordinates (0.29, 0.57).     

Heteroleptic tris-cyclometalated iridium(III) complexes with phenylpridine and diphenylquinoline derivative ligands

The synthesis and photophysical study of efficient phosphorescent heteroleptic tris-cyclometalated iridium(III) complexes having two different (C^N) ligands are reported. In order to improve the luminescence efficiency by avoiding triplet-triplet (T-T) annihilation, new heteroleptic tris-cyclometalated iridium complexes, Ir(ppy)₂(dpq), Ir(ppy)₂(dpq-3-F) and Ir(ppy)₂(dpq-CF₃), are designed and prepared where ppy, dpq, dpq-3-F and dpq-CF₃ represent 2-phenylpyridine, 2,4-diphenylquinoline, 2-(3-fluorophenyl)-4-phenylquinoline, and 4-phenyl-2-(4-(trifluoromethyl)phenyl)quinoline, respectively. Ppy ligands and dpq derivatives can act as a source of energy supply. When new heteroleptic tris-cyclometalated iridium complex, Ir(ppy)₂(dpq-3-F) is placed in the lowest excited state, the excitation energy is neither quenched nor deactivated but quickly intermolecularly transferred from two ppy ligands to one luminescent dpq-3-F ligand. Such transfer can occur because the triplet energy level of Ir(ppy)₃ is higher than that of Ir(dpq-3-F)₃ and because Ir(dpq-3-F)₃ was known to have a shorter lifetime than that of Ir(ppy)₃. As a result, Ir(ppy)₂(dpq-3-F) shows strong emission band at 620 nm from dpq-3-F ligand in the end. Thus it allows more reddish luminescent color and improves the luminescence by the decrease of quenching or energy deactivation by decreasing the number of the luminescent ligand. To analyze luminescent mechanism, we calculated these complexes theoretically by using computational method.     

Photoluminescence characteristics of Ti2S3 nanoparticles embedded in sol–gel derived silica xerogel

Ti₂S₃ nanocrystallites embedded in sol–gel derived silica xerogel have been prepared. Their photoluminescence (PL) characteristics have been evaluated and compared with those of pure silica xerogel. UV–vis absorption spectra, transmission electron micrograph, excitation spectra and PL spectra of the doped and undoped samples have all been investigated. Two emission peaks have been observed from the doped samples, one at 440 nm (λ_ex=380 nm) while the other at 600 nm (λ_ex=550 nm). The latter has been assigned to the Ti₂S₃ nanocrystallites in the silica xerogel. Therefore, a novel luminescence property can be observed by introducing the semiconductor nanoparticles into the silica xerogel.     

Efficient red electrophosphorescent organic light-emitting diodes based on the new sensitized heteroleptic tris-cyclometalated Ir(III) complexes

Organic light-emitting device (OLED) was fabricated using the novel red phosphorescent heteroleptic tris-cyclometalated iridium complex, bis(2-phenylpyridine)iridium(III)[2(5′-methylphenyl)-4-diphenylquinoline] [Ir(ppy)₂(dpq-5CH₃)], based on 2-phenylpyridine (ppy) and 2(5′-methylphenyl)-4-diphenylquinoline (dpq-5CH₃) ligand. Generally, the ppy ligand in heteroleptic iridium complexes plays an important role as “sensitizer” in the efficient energy transfer from the host (CBP; 4,4,N,N′-dicarbazolebiphenyl) to the luminescent ligand (dpq-5CH₃). We demonstrated that high efficiency through the “sensitizer” can be obtained, when the T₁ of the emitting ligand is close to T₁ of the sensitizing ligand. The device containing Ir(ppy)₂(dpq-5CH₃) produced red light emission of 614 nm with maximum luminescence efficiency and power efficiency of 8.29 cd/A (at 0.09 mA/cm²) and 5.79 lm/W (at 0.09 mA/cm²), respectively.     

稀土氧化物对SPS烧结AlN陶瓷电性能的影响

以AlN粉末为原料, 添加稀土氧化物(Sm₂O₃、Y₂O₃), 在氮气气氛下, 采用SPS烧结方法制备AlN陶瓷, 研究稀土氧化物的掺杂对AlN烧结试样相组成、微观结构和电性能的影响。实验表明: Sm₂O₃、Y₂O₃与Al₂O₃反应生成的液相稀土金属铝酸盐会提高AlN陶瓷致密度, 且在晶界处形成导电通路降低了AlN陶瓷电阻率。随着Sm₂O₃掺杂量的增加, 晶界相逐渐由Sm₄Al₂O₉过渡到SmAlO₃, 且Sm₄Al₂O₉对电阻率贡献最大。其中, 3wt% Sm₂O₃掺杂AlN陶瓷电阻率最低, 为      

Optical characteristics of organic light emitting diode with IrQ(ppy)2-5Cl and its emitter

The synthesis and photophysical study of a cyclometalated mixed-ligand iridium(III) complex are reported. The iridium complex (called IrQ(ppy)₂-5Cl) has two cyclometalated 2-phenylpyridine (ppy) ligands and one 8-hydroxyquinoline (Q) ligand, where one of the H atom is substituted by Cl atom. Absorption and photoluminescence spectra are studied for the neat film and films of IrQ(ppy)₂-5Cl doped in 4,4′-N,N′-dicarbazole-biphenyl and polystyrene, together with the electroluminescence spectra using multi-layer light emitting devices. The electronic states are studied using density functional theory calculations. Emission bands are observed at 502 and 666 nm, which arise from ppy and Q ligands, respectively.     

Observation of phosphorescence from fluorescent organic material Bebq2 using phosphorescent sensitizer

Absorption, emission and excitation spectra of bis(10-hydroxybenzo [h] quinolinato)-beryllium (Bebq₂) were studied using polystyrene film doped with 5 wt% Bebq₂, N,N-di(naphthalene-1-yl)-N,N-diphenyl-benzidene (NPB) film doped with 60 wt% Bebq₂, and neat film. The monomer and aggregate of Bebq₂ give fluorescence at 492 and 511 nm at 12 K, respectively. A strong T₁ emission with a vibronic structure was observed from Bebq₂ below 70 K by heavily doping with phosphorescent tris(2-phenylpyridine) iridium [Ir(ppy)₃]. The T₁ energy of Bebq₂ was estimated to be 2.26 eV from the onset of the 573 nm 0–0 vibronic emission band. The energy transfer mechanism from Ir(ppy)₃ to the T₁ state of Bebq₂ is discussed.     

Densification and Grain-Growth Behavior of Various Amounts of SiO2 Doped 8YSCZ/SiO2 Composites

The effect of SiO₂ addition on densification and grain-growth behavior of 8YSCZ/SiO₂ composites was investigated using high purity 8 mol% yttria-stabilized cubic zirconia powders (8YSCZ) doped with 0, 1, 5, 10 wt% SiO₂. The specimens were sintered at 1400°C for 1 hour. It was seen that the sintered density increased with SiO₂ content up to 1 wt% and further increase in SiO₂ content led to a decrease in density. The enhanced density with increasing SiO₂ content up to 1 wt% could be mainly attributable to liquid phase sintering. For grain growth measurements, the specimens sintered at 1400°C were annealed at 1400, 1500, and 1600°C for 10, 50, and 100 hours. The experimental results showed that the grain growth in 8YSCZ/SiO₂ composites occurred more slowly than that in undoped 8YSCZ. Also, the grain growth rate decreased with increasing SiO₂ content. The grain growth exponent value and the activation energy for undoped 8YSCZ were found to be 2 and 289 kJ/mol, respectively. The addition of SiO₂ raised the grain growth exponent value to 3, and activation energy for the grain growth process was increased from 289 to 420 kJ/mol for the addition of SiO₂ from 0 to 10 wt%.