水热法制备碳纳米纤维与氧化锌复合材料

将静电纺丝技术制备的碳纳米纤维（CNFs）作为衬底材料,利用水热方法,通过改变水热反应温度和反应溶液浓度进行对比实验,得到制备碳纳米纤维（CNFs）与氧化锌（ZnO）复合材料的最佳方法.将获得的产物通过场发射电子扫描显微镜（FE-SEM）和X射线粉末衍射（XRD）检测,结果显示,ZnO纳米粒子成功的生长在CNFs表面上,而没有聚集在一起,生长在CNFs表面上的氧化锌纳米粒子的密度可通过反应溶液的浓度控制.     

铝掺杂氧化锌陶瓷制备研究

导电氧化锌陶瓷用作靶材通过磁控溅射等薄膜制备技术在玻璃衬底表面沉积透明导电氧化锌薄膜,可用作价格昂贵的氧化铟锡透明导电薄膜的替换材料。氧化锌陶瓷的掺杂将直接影响到氧化锌薄膜的电学性能,因此对氧化锌陶瓷掺杂研究非常必要。氧化锌本身氧空位的存在显示出n型半导体的性质,通过铝离子掺杂能够显著提高载流子浓度。依据此机理,通过液相反应法和陶瓷工艺合成了铝掺杂氧化锌陶瓷,并对其电学性能进行了分析研究。结果显示氧化锌陶瓷电阻率随着铝掺杂量的增加先降低后升高,铝掺杂浓度1%时电阻率最低。     

应用于光电阴极的SiO2纳米孔阵列

目前以正电子亲合势K₂CsSb为代表的光电发射阴极材料因其有源层较薄的特征使其光吸收能力较差,现成为限制其提升性能的重要因素之一。以聚苯乙烯(PS)纳米球剥离法制备的金属孔阵为掩膜,在SiO₂衬底上刻蚀制备纳米孔阵列。首先刻蚀单层自组装PS纳米球以改变尺寸,然后在表面沉积镍膜并进行剥离获得孔阵掩膜,最后刻蚀SiO₂衬底并去除掩膜获得孔阵。通过改变PS纳米球的自组装和刻蚀工艺参数实现了对纳米孔阵的孔径、深度、周期等几何参数的灵活调节,并通过优化离子刻蚀的频率、反应气体配比等参数有效降低了纳米孔刻蚀面的粗糙度,最后结合实验测试和理论仿真探索了其光学特性,研究结果表明纳米孔阵列能够提高光电发射器件的光吸收率,具有重要应用价值。     

ZnO纳米棒阵列的可控生长与表征

采用化学溶液法在沉积了ZnO种子层的SnO2:F导电玻璃衬底上,生长了ZnO纳米棒阵列。研究了1,3-丙二胺浓度对纳米棒阵列的形貌结构的影响规律。采用扫描电镜(SEM),X射线衍射(XRD)对ZnO纳米棒的表面形貌和晶格结构进行了表征。SEM结果表明纳米棒阵列垂直衬底表面生长,XRD结果表明纳米棒生长方向沿着[002]晶向,具有单晶结构。1,3-丙二胺浓度对制备得到的纳米棒形貌、长度等有明显调控作用。在优化条件下生长的ZnO纳米棒的长度大约7m,根部直径150nm,尖端直径大约10nm。研究了ZnO纳米棒阵列的光致发光(PL)特性。     

我国碳化硅材料衬底产品研制获重大突破

<正>山东天岳晶体材料有限公司承担的"4英寸高纯半绝缘4H-SiC单晶衬底材料"项目通过科技成果鉴定。专家认为,山东天岳公司自主研制的4英寸高纯半绝缘碳化硅(SiC)衬底产品性能达到国际先进、国内领先水平。碳化硅基微波功率器件具有高频、大功率、耐高温等特性,是新一代雷达系统的核心器件。长期以     

n-InP在浓电解质溶液中的光电化学稳定性

本文研究了支持电解质KCl浓度对n—InP光电化学稳定性的影响,指出在pH=1的饱和KCl溶液中,光照时能够形成1—2个分子层厚度的表面氧化膜,这层膜的存在能够保护电极免受光腐蚀,而不降低光生空穴的界面迁移速度。     

钒-钛二元氧化物介孔材料的合成、表征及催化应用

以月桂酸和十二胺为模板剂,硫酸钛和偏钒酸铵为金属源,通过溶胶-凝胶法合成,经过焙烧得到一系列不同钒/钛物质的量比的钒-钛二元氧化物介孔材料。采用XRD、BET等多种手段对介孔材料进行了表征。结果表明,所制备的V-Ti-O为介孔结构;有部分的金属钒进入了介孔的骨架中,其余可能以V2O5形式存在于介孔的表面,n(V)/n(Ti)可达0.43;随着n(V)/n(Ti)增加,孔径增大,但介孔的规整度降低。所合成的材料在苯的羟基化反应中表现出良好的催化活性。     

基于硼酸溶液处理的GaAs/InP低温晶片键合技术

提出了一种基于硼酸溶液的GaAs/InP低温晶片键合技术,实现了GaAs/InP基材料间简单、无毒性的高质量、低温(290℃)晶片键合。GaAs/InP键合晶片解理截面的扫描电子显微镜(SEM)图显示,键合界面整齐,没有裂缝和气泡。通过键合过程,InP上的In0.53Ga0.47As/InP多量子阱结构转移到了GaAs基底上。X射线衍射及荧光谱显示,键合后的多量子阱晶体质量未变。二次离子质谱(SIMS)和Raman光谱图显示,GaAs/InP键合晶片的中间层厚度约为17 nm,界面处B元素有较高的浓度,键合晶片的中间层很薄,因此可以得到较好的电学、光学特性。     

TiO2纳米粉体对变压器油工频击穿性能的影响

纳米半导体晶体表面存在大量的本征表面态,当晶体与变压器油接触时可生成能够有效捕获电子的表面态.考察了不同浓度TiO2纳米粒子对变压器油的改性作用,并以具有不同表面修饰状态的纳米二氧化钛粉体为改性剂,对克拉玛依25号变压器油进行改性,研究了纳米粉体表面修饰种类对改性油绝缘性能的影响.击穿性能测试和拟合结果表明:TiO2半导体纳米粉体可以提高变压器油的击穿性能,在一定浓度范围内,TiO2纳米粒子浓度越大,改性变压器油的工频绝缘性能越好;TiO2纳米粉体的表面修饰成分会影响变压器油的击穿性能,乙酸、丙酸和丙酸+己胺的改性作用依次增大;修饰物分子非极性链的越长,对变压器油击穿性能的改善越好.     

钙钛矿敏化TiO_2-SrTiO_3纳米棒太阳能电池的制备及性能研究

采用简单的水热法在FTO(掺杂氟的SnO_2导电玻璃(SnO_2:F))衬底上直接合成了一维取向的单晶金红石型二氧化钛薄膜,然后使用二氧化钛纳米棒作为模板和反应物Sr(OH)_2作为锶源,通过水热反应成功在TiO_2纳米棒阵列的表面沉积了SrTiO3立方纳米颗粒。并以TiO_2-SrTiO_3作为工作电极,钙钛矿型的CH_3NH_3PbI_3和CsSnI_(2.95)-F_(0.05)分别作为光敏剂和电解质组装敏化太阳能电池。通过调整煅烧温度和二次水热反应中Sr(OH)_2溶液的浓度,钙钛矿敏化太阳能电池的光电转换性能有明显改善,最高效率达到0.34%,是未经SrTiO_3修饰样品的2倍。     

Preparation and characterization of novel porous Fe-Si alloys

Porous Fe-Si alloys with different nominal compositions ranging from Fe-10wt% Si to Fe-50wt% Si were fabricated through a reactive synthesis of Fe and Si elemental powder mixtures. The effects of Si contents on the pore structure of porous Fe-Si alloy were investigated in detail. The results showed that the open porosity, gas permeability and maximum pore size of the porous Fe-Si alloys increased with increasing Si contents, indicating that the porosity and pore size can be tailored by changing the Si contents. The pore structure parameter including the open porosity, gas permeability, maximum pore size obeyed the Hagen-Poiseuille formula with the constant G=0.035 m^-1Pa^-1s^-1 for the reactively synthesized porous Fe-Si alloys. The mechanical property of the porous Fe-Si alloys showed applicability in the filtration industries.     

焙烧炭砖孔结构和导热系数与硅粒度变化关系

借助于X射线衍射仪、压汞仪、激光导热仪、扫描电子显微镜和能谱分析仪等测试手段,研究了分别含3种不同粒度硅粉（中位径分别为2．3、45．0、115．6μm）焙烧炭砖试样中的孔结构和导热系数的变化。结果表明,含硅粉的炭砖试样经焙烧后内部均生成pSiC、Si2N2O和石英等相,粒度过粗,试样内有单质硅残留;随着硅粉粒度的减小,生成碳化硅晶须的长径比变小。对所选用的3种粒度硅粉,随着硅粉粒度的减小,焙烧后炭砖试样的孔径分布范围逐渐变窄,小于1μm气孔孔容积变大,而平均孔径变小。受炭砖试样组成和孔结构影响,硅粉粒度变小,导热系数下降。细小气孔容积与导热系数呈反比关系,即细小气孔增多,导热系数下降。     

Dynamic pore wetting and its effects on porous particle flotation: A review

The dynamic pore wetting plays an important role in the flotation of porous particle, such as coal, fly ash, gasification slag, etc. Water phase get into the pores and crevices on the surface and inside of the particles, creating a dense water layer that covers their surface and decreases their floatability. It is important to reduce the adverse impact of dynamic pore wetting on the flotation performance of porous particles. Thus, this review is to highlight the dynamic pore wetting behavior, and its role in the porous particle flotation as well as the proposed regulation methods to weaken the pore wetting. The characterization approaches of the dynamic pore wetting are discussed including the optical method for the capillary and the nuclear magnetic resonance (NMR) method for porous particles. The surface tension and viscosity of liquid significantly affect the pore wetting degree of porous particles during the 60 min wetting process. Pre-wetting time adjustment, pore compression, pore filling, and hydrophobic modifications are introduced to decrease the wetting percentage of pores in porous particles and further improve their flotation performance. This critical review will provide some guidance for studying the dynamic wetting behavior of pores and enhancing the floatability of porous particles.     

Effect of heat treatment of Mn-Cu precursors on morphology of dealloyed nanoporous copper

Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method. The effects of heat treatment of Mn-Cu precursors on alloy phase, morphology and composition of the resultant nanoporous copper were investigated. It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors, which consequently results in a more fully dealloying for forming nanoporous copper. The alloy phase changes from Cu_0.49Mn_0.51 and Cu_0.21Mn_0.79 of non-thermally treated precursor to Cu_0.33Mn_0.67 of heat treated alloy. The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04% (molar fraction) made from the precursor without and with 95 h heat treatment. The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones: the uniform bi-continuous structure zone and the blurry or no pore structure zone. Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor, and the average ligament diameter is 40 nm, far smaller than that from the non-thermally treated precursor, in which the average ligament diameter is estimated to be about 70 nm.     

离子液体中TiO_2-SiO_2复合气凝胶的制备

采用溶胶-凝胶法,正硅酸乙酯(TEOS)和钛酸丁酯(TBT)为硅源和钛源,以离子液体1-丁基-3-甲基咪唑溴盐([HMIM]Br)为模板剂,常压干燥制备了块状TiO2-SiO2复合气凝胶。通过SEM、TEM、XRD、FT-IR及N2吸附-脱附法对复合气凝胶的结构进行了表征,并对其光催化性能进行相关研究。制备的n(Ti)∶n(Si)∶n(ILs)=2∶1∶0.5的TiO2-SiO2复合气凝胶具有多孔结构,其孔径为3.216nm,孔体积为0.418cm3/g,比表面积为519.4m2/g,且对罗丹明B的光降解性能明显高于P25。     

基于MicroCT多孔材料图像的3D特征分析("研究生论坛"稿件)

多孔材料的微观孔隙结构是影响其宏观物性的关键因素,对其孔隙空间结构特征进行分析具有重要研究意义,然而传统方法却难以对其三维孔隙结构进行定量表征。为了探讨有效、准确、客观的表征孔隙空间结构特征的方法,在本研究中,采用MicroCT在不破坏样品的前提下获取多孔材料二维断层序列图。将Chan-Vese(C-V)水平集方法拓展到3D空间实现3D图像分割获取多孔材料三维分析模型,在此基础上提取多孔材料3D孔隙参数,如孔体积、孔表面积、孔径、孔隙率、连通率等空间孔隙结构参数。三维孔隙参数能客观准确地描述多孔材料的孔隙结构,为表征多孔材料孔隙结构提供了新的方法。     

烧结温度对BaTiO3多孔陶瓷性能的影响

采用水基冷冻浇注法制备了具有层状结构的BaTiO3多孔陶瓷,研究了烧结温度对多孔陶瓷微观形貌、收缩率、孔隙率及介电性能的影响,并探讨了高岭土悬浮剂在烧结过程中所起的作用.研究结果表明:高岭土含量4wt%的样品收缩率从1 200℃时的27%升高到1 220℃时的56%,同时孔隙率从78%下降到56%,高岭土含量8wt%的样品收缩率从1 200℃时的30%升高到1 220℃时的61%,同时孔隙率从72%下降到39%;高岭土在烧结过程中起到烧结助剂的作用;烧结温度升高会使孔径变小并导致孔隙排列由有序结构向无序结构转变.高岭土含量为8wt%,烧结温度1 200℃时,可以得到分布均匀的层状结构多孔陶瓷;高岭土含量为4wt%,烧结温度1 220℃时可得到介电常数130的多孔陶瓷.     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr6 and PO43-, constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating's structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgA12O4 and MgO, and the minor phases are Al2O3 and SiO2 when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.     

Wafer bonding technique used for the integration of cubic GaN/GaAs (001) with Si substrate

We successfully used the metal mediated-wafer bonding technique in transferring the as-grown cubic GaN LED structure of Si substrate. The absorbing GaAs substrate was removed by using the chemical solutions of NH4OH : H2O2=1 : 10. SEM and PL resuls show that wafer bonding technique could transfer the cubic GaN epilayers uniformly to Si without affecting the physical and optical properties of epilayers. XRD result shows that there appeared new peaks related to AgGa2 and Ni4N diffraction, indicating that the metals used as adhesive and protective layers interacted with the p-GaN layer during the long annealing process. It is just the reaction that ensures the reliability of the integration of GaN with metal and minor contact resistance on the interface.     

A novel method to determine effective thermal conductivity of porous materials

1 Introduction Due to some unique structure and characteristics, the porous material behaves as afunctional material and is finding more and more applications in a variety of fields suchas aviation, chemistry and energy[1]. In such cases, the effective thermal conductivity ofthe porous materials is a vital parameter that dominates application performances. Gen-erally speaking, the effective thermal conductivity can be measured experimentally, butin some cases (for example the stuffing is l…