Materials Literature
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采用水凝胶空间网孔结构作为纳米级反应容器可控制备了NaYF 4 :Yb 3+ , Er 3+ 稀土上转换发光纳米颗粒。通过控制交联剂密度可以改变网络凝胶网孔结构, 用不同网孔结构的凝胶模板可以控制合成纳米颗粒。通过XRD、TEM、PL等方法研究了不同凝胶模板对颗粒的尺寸、发光性能的影响。结果表明, 利用高分子交联后形成的凝胶网络, 可以制得粒径在10 nm左右的NaYF 4 :Yb 3+ , Er 3+ 纳米颗粒。随着交联剂浓度的升高, 颗粒粒径及荧光强度都有所下降。本研究为稀土上转换发光纳米颗粒的制备提供了工艺简单、绿色环保的新方法。
采用真空烧结固相反应法, 分别制备了不添加和添加烧结助剂(正硅酸乙酯TEOS和MgO)的Pr:LuAG ( Pr: Lu 3 Al 5 O 12 )陶瓷, 研究发现添加烧结助剂烧制的Pr:LuAG陶瓷在可见光区的直线透过率可达～80%, 不添加烧结助剂的陶瓷光学透过率降低(可见光区~70%, 2 mm厚), 但光输出提高了5倍(为1196 pe/MeV), 衰减快分量比例可达73%, 能量分辨率8.4%。将Pr:LuAG陶瓷加工成1.9 mm×1.9 mm×1.0 mm的陶瓷阵列组装探测器模块, 用4×4陶瓷阵列单元实现了二维散点图成像, 所成散点图清晰可辨。经过平台测试, 相同耦合条件下本实验制备的Pr:LuAG陶瓷成像质量优于…
研究了MgAl水滑石(LDH)焙烧产物(LDO)对Cr(VI)的吸附性能。考察了吸附温度对LDO吸附性能的影响, 研究了吸附过程的热力学和动力学行为。结合XRD和FT-IR表征, 阐明其吸附机理。结果表明, CrO 4 2– 已成功插入水滑石层间, 适当提高吸附温度有利于LDO恢复LDH晶相。在20~60℃范围内, 随吸附温度升高, LDO对Cr(VI)吸附量增大, 50~60℃时, Cr(VI)吸附量为91 mg/g。Cr(VI)的吸附平衡数据符合Langmuir模型方程, Δ G o 为负值说明吸附过程为自发过程, Δ S o 和Δ H o 为正值表明吸附为熵增的吸热过程。吸附动力学符合伪二级动力学模型, LDO 的吸附活化能…
采用溶剂热法, 以CuCl 2 ·2H 2 O、Zn(Ac) 2 ·2H 2 O、SnCl 4 ·5H 2 O作金属源, 硫脲作硫源, 乙二醇作溶剂, PVP作表面活性剂, 制备了Cu 2 ZnSnS 4 (CZTS)粉末。利用XRD、SEM、Raman、TEM、EDS、UV-Vis吸收光谱探讨了反应温度和反应时间对制备CZTS粉末的相结构、成分、形貌以及光学性能的影响。结果表明: 反应温度和反应时间对CZTS粉末的颗粒形貌和光学性能影响较大, 最佳合成温度为230℃, 反应时间24 h。该条件下生成的CZTS粉末相较为纯净、结晶完全, 形貌为表面嵌有薄片的微球, 各元素原子比接近化学计量比, 光学带隙为1.52 eV, 与太阳能…
本研究以γ-AlOOH、TiO 2 和SiC为原料, 通过无压反应烧结制备了Al 2 TiO 5 多孔材料, 分析比较了SiC粒度和含量对合成产物的物相组成、显微组织、抗压强度、孔隙率和孔径分布的影响。结果表明: 反应产物的物相组成为Al 2 TiO 5 、Al 6 Si2O 13 、TiC、SiO 2 和Al 2 O 3 , 还有少量未反应的TiO 2 。SiC与TiO 2 反应生成TiC和SiO 2 , TiC颗粒弥散分布于多孔材料壁面或者骨架中, 而SiO 2 进一步与γ-AlOOH分解出的Al2O3反应生成Al 6 Si 2 O 13 晶须, 晶须交错分布于Al 2 TiO 5 颗粒之间或者孔洞中, 与TiC颗粒一起提高复…
采用等离子体增强化学气相沉积法(PECVD)制备了多孔SiO 2 薄膜, 系统地研究了不同浓度磷酸处理对多孔SiO 2 薄膜的质子导电特性、双电层电容和以此多孔SiO 2 薄膜为栅介质的铟锌氧(IZO)双电层薄膜晶体管性能的影响。结果表明: 多孔SiO 2 薄膜的质子电导率和双电层电容随磷酸浓度升高而增大, 60%浓度磷酸处理后多孔SiO 2 薄膜质子电导率和双电层电容分别达到1.51×10 -4 S/cm和6.33 μF/cm 2 。随磷酸浓度升高, 双电层薄膜晶体管的工作电压降低, 并且, 电流开关比也变大。其中60%浓度磷酸处理后器件工作电压为1.2 V, 迁移率为20 cm 2 /(V·s), 电流开关比为4×10 6 。…
采用搅拌熔铸法制备Al-Fe-Si/Al原位复合材料。利用X线衍射仪（XRD）、扫描电镜（SEM）、能谱分析（EDS）、光学显微镜、XHV-1000数字式显微硬度计、MFT-4000多功能材料表面性能试验仪研究Fe含量对原位复合材料的微观结构、硬度和耐磨性的影响。结果表明：Fe的质量分数为2%时原位复合材料的组织是以长针状的金属间化合物的β-Al5Fe Si为主,并含有少量Al0.3Fe3Si0.7;随着Fe含量的增加,原位复合材料中长针状的β-Al5Fe Si逐渐由长针状长大成粗棒状最后长大成块状;当Fe的质量分数为6%时,复合材料的硬度最高,为108.64HV,约为纯铝的3倍,约为ZL102的1.5倍;表面摩擦性能最佳,摩擦因…
Established in 1964, the IUCN Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species.
In this letter, we examine the role of Coulomb interactions in the emergence of macroscopically ordered states in graphene supported on hexagonal boron nitride substrates. Due to incommensuration effects with the substrate, graphene can develop gapped low energy modes that spatially conform into a triangular superlatt…
通过添加固体润滑剂h-BN,采用真空热压烧结工艺制备TiB2/WC/h-BN自润滑陶瓷材料,对其密度和力学性能进行测试,并采用XRD和SEM对材料的物相和显微结构进行分析.结果表明：TiB2/WC/h-BN自润滑陶瓷材料的相对密度为97.5％,抗弯强度、断裂韧性和维氏硬度分别为652MPa、4.5MPa·m1/2和14.8GPa.片状结构的固体润滑剂h-BN颗粒保存完整,分布均匀,而且可有效抑制基体TiB2晶粒的长大.材料的断裂模式是穿晶/沿晶断裂的混合型,以穿晶断裂为主.材料的增韧机理以裂纹偏转和裂纹桥联为主.TiB2/WC/h-BN自润滑陶瓷材料的摩擦因数低于0.3,与其他添加h-BN的自润滑陶瓷材料相比,具有良好的力学性能和…
Thermal runaway in chemical batch and semibatch reactors is one of the major plagues in fine chemical, pharmaceutical and plastic industries. Quite often the root cause of such events is a poor knowledge of the process kinetics and thermodynamics. For this reason, accidents continue to occur with a high frequency in b…
A ''two-in-one'' approach, namely, through deposition of APTES-functionalized Al2O3 particles onto a coarse macroporous support, was applied to synthesize zeolitic imidazolate tramework-7 (ZIF-7) membranes. The ef- fect of molar ratio of APTES and Al2O3 particles on the formation of ZIF-7 membranes were investigated i…
Sulfosalicylic acid intercalated Mg/Cu/Al-LDHs composite material was prepared by coprecipitation method. The as-prepared material was characterized by XRD, FT-IR and TG-DTA measurements. It was found that the object was intercalated into LDHs layers and the layer distance changed from 0.832 nm to 1.125 nm. Based on t…
The present work discusses the use of dynamic process simulators as supporting tools for the quantitative risk assessment of industrial facilities. In particular, a commercial process simulator was set up for the analysis of industrial accidents, obtaining on one side a detailed characterization of the source term in…
We have performed DFT calculations to devise some possible fullerene dimers (from $C_{60}$ and $C_{80}$ ) connected through $C_{24}$ and $C_{36}$ bridge cages with the face-to-face linking model. The fullerene dimers with $C_{36}$ bridges have lower binding energies and greater HOMO-LUMO gaps than those of the fullere…
E-mail: sshin@snu.ac.kr (S. Shin); sisid1@snu.ac.kr (C. Shin)Received October 25, 2013, Accepted December 11, 2013Time-dependent formulations of the reactive scattering theory based on the wavepacket correlation functionswith the Moller wavepackets for the electronically nonadiabatic reactions are presented. The calcu…
The molecular structures of 2,6-diaza-1,3,5,7-tetraoxaspiro[3,3]heptane (1) and its dinitro derivative, 2,6-dinitro-2,6-diaza-1,3,5,7-tetraoxaspiro[3,3]heptane (2), were fully optimized without symmetry constraints at $HF/6-31G^*$ level of theory. A bisected conformation with respect to the ring is preferred with a $C…
The adsorption behavior of the sulphate ( $SO{_4}^{2-}$ ) on the external surface of (5,0), (8,0), and (10,0) zigzag AlNNTs was studied by using density functional calculations. Adsorption energies in the nanotubes are about -8.59, -8.04, -8.60 eV with a charge transfer of 0.59, 0.48, 0.56|e| from the sulphate ion to…
This paper reports the application of specific trend’s consistency of Full Hydrogenation (FH) of SCPOFA to establish operating conditions for providing new product of Partially Hydrogenated (PH) fatty acid, an Intermediate Raw Material (IRM) of a mixed fatty acid T40, which is a modification of fatty acid products. Co…
Cobalt ferrite powders with excellent infrared radiation property were synthesized via the Sol-Gel method, where iron nitrate and cobalt nitrate were used as the original materials and citric acid as the chelating reagent. The effects of pH of the starting solution (pH=1, 3, 5 and 7) on the infrared radiation property…