包埋碳纳米管凝胶球的制备及吸附性能研究

以海藻酸钠(SA)和聚氧化乙烯(PEO)为包埋剂、碳纳米管(MWNTs)为吸附剂、CaCl2为凝固剂制备了复合凝胶球。探讨了PEO含量和分子量对凝胶球状态的影响,并研究了包埋剂用量、MWNTs用量、吸附时间和pH值对Cr2O27-吸附去除性能的影响。实验表明:当SA为2%(质量分数,下同)时,PEO分子量为10×104、含量为0.5%的凝胶球可形成均一尺寸;包埋剂SA/PEO对Cr2O27-没有吸附能力;在25mL、4mg·L-1的Cr2O27-溶液中,当MWNTs用量为60mg时,吸附2h后达到平衡,去除率达到95.3%;在酸性溶液中的去除率大于中性和碱性溶液。     

具有吸附特性3A沸石/PI复合膜的制备与性能

采用原位聚合法制备了具有吸附特性的3A沸石/聚酰亚胺(PI)复合膜,并考察了复合膜的亚胺化程度、微观形貌、力学性能、吸附/脱附行为。结果表明,复合膜亚胺化完全、力学性能优良;3A沸石均匀分散在PI基体内,二者之间界面结合良好;水为吸附质时,分散在PI基体中的3A沸石仍能保持对水的吸附性能,且最大脱附量达23.39 g H2O/100 g3A沸石。该复合膜在吸附分离、膜分离及包装等领域中具有潜在的用途。     

壳聚糖/Y2O3/聚丙烯无纺布复合膜的制备及其性能研究

采用戊二醛作为交联剂,采用溶液共混和表面延流法制备壳聚糖/Y2O3/聚丙烯无纺布复合膜。采用IR、DSC、SEM对复合膜进行表面结构表征;对复合膜的结合牢度以及复合膜对磷的吸附性能进行测试。结果表明:壳聚糖和Y2O3颗粒都比较均匀分散在复合膜的表面;处理后的复合膜吸热峰值没有明显变化;当壳聚糖固定时,复合膜的结合牢度随Y2O3用量的增加逐渐降低,当Y2O3用量固定时,复合膜的结合牢度随壳聚糖用量的增加逐渐增大。聚丙烯无纺布经过壳聚糖/Y2O3处理后,对磷具有一定吸附作用,吸附性能优于纯壳聚糖涂敷膜。     

氧化石墨烯/海藻酸钙水凝胶复合膜对水中Cd(II)的吸附

将氧化石墨烯(GO)、致孔剂与海藻酸钠共混后与CaCl₂交联制备的GO/海藻酸钙（CA）水凝胶复合膜作为含重金属废水的吸附材料。采用SEM和TEM表征了复合膜的表面形貌及透射性能,且分析了GO的加入对复合膜的力学性能、平均孔径、水通量及表面官能团的影响。为探究GO/CA水凝胶复合膜的吸附性能,考察了其吸附Cd(II)的影响因素:pH（6~7）值、初始离子浓度、接触时间、温度（三者均正相关）。用FTIR、XPS在吸附前后对复合膜进行了表征;引入了吸附动力学和等温线模型分析其吸附机制。探究结果表明GO的加入提高了复合膜的力学性能、平均孔径及水通量;吸附过程遵循Langmuir等温线,属于单层吸附,拟合得到的最大吸附量为173.61 mg/g;伪一级和伪二级吸附动力学分别在低浓度和高浓度时能较好地描述吸附过程的动力学行为;吸附机制主要为物理作用力吸附和离子交换。经过5个连续的吸附-解吸循环证明了GO/CA水凝胶复合膜的可重复利用性。      

壳聚糖/聚乙烯醇/CeO2三元复合膜的制备及其性能研究

CeO2经阴离子表面改性剂SDS表面改性后,采用溶液共混法制备了壳聚糖/聚乙烯醇/CeO2复合膜,采用扫描电子显微镜(SEM)对复合膜的表面形貌进行表征;傅里叶红外光谱(FTIR)研究吸附前后复合膜上基团的变化;热重分析仪(TG)分析复合膜的热稳定性;测试复合膜的力学性能及溶胀率并进行分析,探讨CeO2和PVA的加入对壳聚糖膜力学性能和吸水率的影响;采用二苯碳酰二肼分光光度法研究时间对Cr(Ⅵ)吸附的影响.实验结果表明:改性后的CeO2在复合膜中分散均匀,与复合膜的相容性较好.随着CeO2的增加,复合膜的热稳定性提高,断裂强力和断裂伸长率增大,溶胀率下降,相比较纯壳聚糖膜,断裂强力最大可提高47.4％,溶胀率最大可下降53.9％.复合膜对Cr(Ⅵ)的平衡吸附量可以达到11.2mg/g.     

TiO_2/MWNTs/Al_2O_3复合分离膜的制备及其水处理性能

以氧化铝陶瓷膜为基底,采用化学气相沉积法制备了具有光催化性能的TiO2/多壁碳纳米管(MWNTs)/Al2O3复合分离膜,通过控制TiO2的沉积时间实现对膜孔径的有效调控.实验结果表明,当化学气相沉积时间为10min时,复合膜具有较好的纯水通量、截留性能和光催化性能.根据紫外漫反射谱图(DRS)分析,TiO2/MWNTs/Al2O3复合分离膜比单独的TiO2/Al2O3复合分离膜具有更好的光吸收性能,能量色散X射线光谱(EDX)的元素分布图显示,TiO2纳米颗粒均匀分布于复合膜表面.以浓度为15mg/L的腐植酸为目标物,考察了复合光催化膜的水处理性能,结果表明,光催化与膜分离耦合工艺可以显著提高有机污染物的去除效率,60min内对腐植酸的去除率可达80.9%,相比于单独的膜分离工艺高12.2%;同时能够有效缓解膜面污染,连续运行5h后,耦合工艺下复合膜的渗透通量比单独膜分离高70.9%.     

基于P_2O_5/SiO_2与磺化聚醚醚酮合成的无机/有机复合质子交换膜

采用溶胶-凝胶法制备P2O5/SiO2溶胶与P2O5/SiO2粉末,之后分别与磺化聚醚醚酮(SPEEK)复合,制得无机/有机复合质子交换膜并研究了两种膜的形貌、力学性能以及质子电导率。与纯SPEEK膜相比,P2O5/SiO2无机成分的引入能显著改善复合膜的质子导电性能。同时,P2O5/SiO2的不同引入方式导致复合膜具有不同的结构,进而引起复合膜力学性能与质子导电性能上的差异。在所制备的无机/有机复合膜中,含有40%P2O5/SiO2(质量分数)粉末的复合膜的质子电导率达到1.6×10-2 S/cm,其所组装的单电池的开路电压为0.95V,峰值功率密度达到446mW/cm2。     

聚氨酯/碳纳米管复合材料的制备及其对血小板黏附的抑制作用

通过原位聚合的方法将官能化碳纳米管引入聚氨酯中制备了聚氨酯/碳纳米管复合材料(PU/MWNTs),并对其物理学性能和生物学功能进行了研究.通过差示扫描量热法和拉伸性能测试对材料的基本性能进行了研究;通过血小板黏附实验评价了复合材料的生物学性能.结果表明,PU/MWNTs材料的玻璃化温度升高、力学性能得到了提高,碳纳米管(CNTs)的加入使复合材料显示出与聚氨酯基体材料不同的血小板吸附行为,尽管MWNTs的增加明显促进了纤维蛋白原的吸附,但PU/MWNTs表现出对血小板黏附和活化有抑制作用.     

氧化石墨烯/海藻酸钠复合膜对Pb(Ⅱ)的吸附性能和机制

海藻酸钠（SA）基的过滤膜是处理含Pb（Ⅱ）废水的理想膜分离材料,将氧化石墨烯（GO）和尿素添加进SA中,以CaCl₂溶液交联,制备出GO/SA复合膜,并考察了其对水溶液中Pb（Ⅱ）的吸附性能。通过静态吸附实验,探讨了Pb（Ⅱ）初始浓度、GO质量分数、初始pH值和吸附时间、吸附-解吸次数等对GO/SA复合膜吸附Pb（Ⅱ）效果的影响;对吸附过程进行了吸附动力学和吸附热力学分析,利用FTIR-ATR、XPS等对GO/SA复合膜吸附Pb（Ⅱ）的机制进行了解析。结果表明,GO/SA复合膜对Pb（Ⅱ）的吸附量与Pb（Ⅱ）初始浓度正相关,在pH=5时吸附效果最优,GO质量分数为0.3wt%时为最优配比;吸附过程符合伪二级动力学模型;热力学等温吸附过程符合Langmuir等温吸附模型,温度为318 K时,Langmuir模型拟合得到的GO/SA复合膜吸附量达到320.51 mg·g-1。GO/SA复合膜对Pb（Ⅱ）的吸附机制主要为物理吸附。      

乙基纤维素/TiO2复合膜的制备及气体渗透性能

以乙基纤维素(EC)和正钛酸丁酯(TBT)为主要原料,通过溶胶-凝胶(Sol-Gel)法制备了EC/TiO2复合膜。研究了TiO2粒子在复合膜中分布形貌、复合膜的结构变化及对气体渗透和分离性能的影响。结果表明,TiO2质量分数达到25%时,微米级的TiO2粒子均匀分散在复合膜中,复合膜形成有机-无机三维网络结构,测试气体在膜中的渗透行为主要受动力学因素控制,其中H2、O2透气系数分别增大至纯EC膜的1.8倍和1.3倍,H2/N2及O2/N2分离性能略有提高。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.