二元胶体晶体及二氧化硅复杂有序介孔膜的制备

采用模板辅助电场诱导沉积和加速蒸发诱导共沉积两种方法,用聚苯乙烯微球制备了高度有序的二元胶体晶体结构.通过溶胶凝胶法填充这些模板结构,并经过热处理后获得具有复杂有序多孔结构的二氧化硅薄膜.SEM结果表明,所得薄膜较好地复制了胶体晶体模板的结构,薄膜孔径与微球直径相比有一定程度的收缩.与普通多孔膜相比,这种有序多孔膜具有更复杂的结构以及更高的比表面积,在分离提纯、催化剂及光子带隙材料等领域具有一定的应用前景.     

模板法制备结构可控纳米材料的研究进展

综述了模板法制备结构可控纳米材料的研究进展,讨论了模板法可控制备纳米材料的原理及高度有序自组装的纳米多孔Al2O3模板的形成机理。重点介绍了纳米材料的可控制备方法,主要包括纳米多孔Al2O3模板法、聚合物模板法和生物模板法。其中纳米多孔Al2O3模板法又分为电化学纳米多孔Al2O3模板合成法和电化学诱导的溶胶-凝胶方法等。根据材料的物化性能,选用适合的模板,采用合理的工艺路线,可以制备出结构可控的纳米材料。     

金纳米粒子的组装及光谱特征

通过对玻璃基底的硅烷基化,金纳米粒子被组装到玻璃基底上,SEM表明金纳米粒子在玻璃基底上形成二维的亚单层组装结构.同时又利用聚苯乙烯模板对金纳米粒子进行图案化组装,在玻璃基底上形成"面包圈"结构.     

纳米TiO2包覆SiO2粒子的制备与表征

以微乳法制备的SiO2凝胶粒子(100℃干燥)为核,通过溶胶-凝胶工艺包覆纳米TiO2层,并对纳米TiO2包覆SiO2粒子进行相组成和结构表征.实验结果表明纳米TiO2包覆SiO2所形成的复合粒子的粒径为250 nm左右,其中纳米TiO2包覆壳层较均匀,厚度约为20 nm～40 nm.随煅烧温度的提高(550℃→850℃),包覆纳米TiO2壳层的晶粒尺寸可控制在20 nm以下,且为锐钛矿晶型结构.XPS和FT-IR证实所制备的纳米TiO2壳层与所包覆的SiO2粒子之间形成了Ti-O-Si化学键合.     

单层氧化锌有序孔膜的制备与性质

采用电化学沉积方法,结合胶体晶体模板,通过循环伏安方法对体系的电化学特性进行研究,获得一种良好的低沉积速度的制备工艺,即通过合适的电位恒电势法,最终获得了单层二维的氧化锌有序孔膜结构.对应于不同的沉积厚度,所得有序孔的形貌也会有所不同.通过扫描电子显微镜对该氧化锌有序多孔膜结构进行了表征,并研究了相应的光致激发特性,二维氧化锌有序多孔膜在384 nm表现出明显光致激发峰,激发峰的位置没有因单层有序孔阵列结构存在而有明显改变.     

AuCu籽晶界面诱导合成FeCo硬磁纳米粒子

FeCo纳米粒子是优良的磁性材料，具有重要的潜在应用价值。但通常制备的FeCo纳米材料矫顽力低，属于软磁材料。提出了一种新颖的湿化学方法合成FeCo硬磁纳米粒子：首先制备L1₀-AuCu籽晶纳米粒子，然后Fe、Co原子沉积在籽晶外层外延生长，获得具有核壳结构的AuCu@FeCo纳米粒子，利用有序结构的L1₀-AuCu籽晶界面，诱导FeCo外壳形成硬磁纳米粒子。AuCu籽晶粒子合成中，随着反应温度增加，AuCu籽晶逐渐从无序向有序转变，同时粒子的形貌和分散性也逐渐改善，在340℃时，获得了分散性好、有序度高的L1₀-AuCu籽晶纳米粒子；FeCo添加量对FeCo外壳的形貌和磁性能有重要影响，当FeCo添加量x=0.085 mmol时，获得了具有良好分散性的AuCu@FeCo硬磁纳米粒子，矫顽力达到605 Oe。提出的界面诱导法为制备良好分散性FeCo硬磁纳米粒子提供了一种新思路。     

湿化学法一步合成高有序L10-AuCu纳米粒子

利用湿化学法成功一步合成出高品质L1₀-AuCu纳米粒子。研究了合成工艺对AuCu纳米粒子的形貌、成分和有序度的影响。研究表明：随着温度的升高,AuCu纳米粒子结构将发生有序转变。当温度高于320℃时,AuCu纳米粒子开始转变为L1₀结构。AuCu纳米粒子中前驱体的添加比例也会影响其形貌和有序度。当金和铜的摩尔比x由小增大时,AuCu纳米粒子的分散度变差,L1₀结构的特征峰强度呈现出先增强后减弱的趋势。在合成温度为340℃,金铜摩尔比x为1.11时,成功获得了粒径小、有序度高、分散性好的AuCu纳米粒子。该制备方法工艺简单,可控性强,为直接合成高品质AuCu有序化纳米粒子提供了新思路。     

纳米银的软模板制备方法及形成机理研究

在聚乙烯醇(PVA)、聚乙烯吡咯烷酮(PVP)和壳聚糖(CTS)等软模板存在下,通过液相化学还原法制备出各种形貌的银纳米粒子.重点讨论了PVP软模板及其浓度、温度、超声等因素对银纳米粒子形貌的影响,运用TEM、XRD、IR、UV-Vis等测试技术对样品进行了表征,探讨了银纳米粒子的形成机理,并对银纳米粒子的光学性质进行了研究.     

玻璃基板上低温制备TiO2膜

以溶胶-凝胶浸渍提拉和氧化法为基础,探讨一种在玻璃基板上制备有序TiO2膜的方法.此方法分为两步先用溶胶-凝胶浸渍提拉法在玻璃基板上预镀一层TiO2膜作为诱导膜,再以钛金属片为钛源,通过溶解-沉淀机制(Dissolution Precipitation Mechanism)于低温下在预制膜上生长有序的TiO2膜.通过X射线衍射(XRD)图谱表征样品的晶体结构,用扫描电镜观察样品的表面形貌.结果表明,在80℃下,TiO2预制膜上可生成一层新的锐钛矿相TiO2膜.要低温情况下在玻璃基板上得到有序TiO2膜还需要进一步改善实验条件,或结合其他的有序膜生长机理来制备.     

基于紫外光辐照法制备CuSe/ZnSe核壳结构纳米粒子

本文成功制备出以CuSe为核心、ZnSe为壳层,具有核壳结构的CuSe/ZnSe纳米粒子。首先采用回流冷凝法制备出CuSe纳米粒子（NPs）。然后,采用一种简单、快速的光化学方法即紫外光辐照法,室温下在CuSe NPs外包覆ZnSe壳层,最终得到CuSe/ZnSe核壳结构纳米粒子。利用X射线衍射(XRD)、能量色散谱仪(EDS)、透射电镜(TEM)、高分辨透射电镜(HRTEM)和光致发光光谱(PL)对合成的CuSe/ZnSe核壳NPs进行了表征。结果分析表明,合成的CuSe纳米粒子具有六方相结构,粒径平均大小在12 nm。制备出的CuSe/ZnSe纳米粒子的核壳结构清晰,生长的ZnSe壳层为立方闪锌矿结构,粒径大小约为15~45 nm。通过ZnSe壳层的包覆使CuSe在475 nm处产生蓝光发射,同时荧光强度显著增强。     

Compositional and structural analysis of RF magnetron sputtered La3+-modified PZT thin films

In the present work, we report the preparation of lanthanum-modified lead zirconate titanate (PLZT) thin films in pure perovskite phase by RF magnetron sputtering. For this purpose, a 3-in. diameter target of PLZT (8/60/40) was prepared by conventional solid-state reaction route. The chemical composition of PLZT target was determined using gravimetric analysis followed by UV–vis and flame atomic absorption spectrometry. Various deposition parameters such as target-to-substrate spacing, deposition temperature, post-deposition annealing temperature and time have been optimized to obtain PLZT films in pure perovskite phase. The films prepared in pure argon at 100 W RF power without external substrate heating exhibited pure perovskite phase after rapid thermal annealing (RTA) as confirmed by X-ray diffraction (XRD). Compositional analysis of the PLZT film was performed by secondary ion mass spectroscopy (SIMS) using PLZT target as standard sample. Depth profile of the film shows very good stoichiometric uniformity of all elements of PLZT.     

多孔泡沫铜支撑锡薄膜阳极材料的制备及性能

以三维多孔泡沫铜为基底,采用化学镀的方法制备锂离子电池薄膜Sn负极材料.利用扫描电镜、X射线衍射分析以及恒电流充放电测试等手段研究不同厚度薄膜Sn电极的形态、结构和电化学行为.结果表明:化学镀工艺制备的Sn电极表面的大量微孔和岛状突起不仅增大电极的表面积,而且显著缓解电极在充放电过程中体积的变化;其中镀层较薄的样品C薄膜Sn电极的初始充电(脱锂)容量为660.6 mA·h/g,经100次循环后,容量保持在299.5 mA·h/g,具有较好的循环性能.     

Composition and processing effects on the electrochemical characteristics of biomedical titanium alloys

The electrochemical behaviour of the Ti–13Nb–13Zr and Ti–6Al–4V ELI alloys with martensitic microstructures was investigated by polarization and electrochemical impedance spectroscopy (EIS) in Ringer’s solution. The impedance spectra were interpreted by a two time-constants equivalent circuit. Both investigated alloys showed high corrosion resistance, but the thin and uniform passive film on the Ti–6Al–4V ELI alloy surface was more protective. The inner barrier and outer porous layer were highly resistant and capacitive. However, thicker and more porous passive film on the Ti–13Nb–13Zr alloy surface may be beneficial for osteointegration. The suitable thermomechanical processing improved the corrosion resistance of Ti–13Nb–13Zr alloy.     

Al-Ti基体上纳米网状钙磷陶瓷/多孔Al2O3生物复合涂层的原位生长

先采用PVD法在医用钛金属表面沉积一层Al膜,得到Al-Ti基体材料;而后采用阳极氧化与水热合成复合制备技术在Al-Ti基体上成功构造了由纳米网状磷酸盐组成的钙磷生物陶瓷/Al2O3多孔复合生物涂层.利用扫描电镜(SEM)、透射电镜(TEM)、电子能谱(EDAX)、X射线衍射(XRD)表征了阳极氧化前后铝膜和钙磷生物陶瓷涂层的微观形貌、元素构成以及晶相成分.结果表明:在阳极氧化过程中,钙、磷元素嵌入阳极氧化铝(AAO)膜,并经水热处理反应原位生成钙磷陶瓷;钙磷陶瓷晶体从Al2O3孔洞长出并覆盖于多孔氧化膜的表面;最终获得的钙磷生物陶瓷/多孔Al2O3复合涂层具有纳米网状、多孔的结构特征.分析探讨了钙磷生物陶瓷/多孔Al2O3复合涂层的原位生长过程,浓度梯度与电位差分别是Ca、P元素进入AAO膜的主要推动力.     

电沉积铁氰化镍测定多孔膜电极的电活性面积

采用电化学方法测定三维多孔膜电极的电活性有效表面积、活性体积和表面覆盖度。以三维多孔电极或沉积有过渡金属铁氰化镍半导体薄膜的三维多孔膜电极为工作电极,分别在含铁氰化钾和不含铁氰化钾的碱金属溶液中测定不同扫描速度下的循环伏安曲线,利用膜电极在不同溶液体系中氧化/还原反应的可逆特性测定其电活性有效表面积和覆盖度;同时结合计时库仑法获得三维多孔膜电极内膜的活性体积和平均膜厚。结果表明:该方法具有电化学反应响应快速、灵敏且精确度高的优点,操作简单且快捷方便,可靠性好。     

ZrO_2／TiO_2复合光催化膜的微弧氧化法制备及表征

采用微弧氧化方法和原位生成的Zr（OH）_4胶体颗粒,在纯钛基体上制备ZrO_2／TiO_2复合光催化膜。采用SEM、EDX、XRD、UV-VisDRS等分析手段,对膜层进行分析表征。结果表明：复合膜显示出层状和多孔的结构,由锐钛矿、金红石和ZrO_2组成;相对于纯TiO_2膜,复合膜层的光吸收截止边缘产生红移;ZnO_2／TiO_2复合膜层和纯TiO_2膜层在紫外光照射下,对罗丹明B的光催化速率常数分别为0．0442和0．0186h~（-1）。     

Microstructure and thermal conductivity of porous ZrO2 ceramics

ZrO₂ ceramics usually have nonuniform microstructures due to the agglomeration of fine ZrO₂ powders. In this paper, the thermal conductivity of porous ZrO₂ ceramics with different microstructures was investigated by the laser-flash method. It was found that the thermal conductivity of porous ZrO₂ ceramics with uniform microstructure was clearly lower than that of ceramics with nonuniform microstructure. Scanning electron microscopy observations showed that porous ceramics with nonuniform microstructures have wider pore and grain size distributions, relative to those with uniform microstructures. Theoretical analyses were done to model the thermal conductivity of porous ceramics using an effective medium approach. These analyses revealed that matrix grain size distribution has a significant impact on the thermal conductivity of porous ceramics, while the effect of pore size distribution is negligible.     

EFFECTS OF OXIDES IN INVESTMENT MOLD ON SURFACE PROPERTIES OF TITANIUM CASTINGS

1.IntroductionLightweight,highstrengthatambientandhightemperatures,andexcellentcorrosionresistancepropertymaketitaniumanditsalloysattractiveengineeringmaterialsinindustry.FOrexample,theapplicationoftitaniumpartsinaerospaceenginecouldnotonlyenhancetheefficiellcyofthecraft,butalsogreatlyreducethefuelconsumption.Butitsrelativelyhighmanufacturingcostshistoricallyhavelimiteditsusetohigh--techapplicationssuchasthatintheaerospacefield.Overthelasttwodecades,however,metallurgicalcastingtechnologydevel…     

Growth of BaTiO3-Ag hybrid composite films at room temperature by aerosol deposition

Barium titanate (BaTiO3) and silver (Ag) composite film with high dielectric constant was grown at room temperature by an aerosol deposition method.The dielectric constant increases by 0.5 times after adding Ag to the BaTiO3 matrix,compared with pure BaTiO3.The high dielectric constant can be attributed to the percolation effect of Ag inclusions in the BaTiO3 matrix.The Ag was present in the form of discrete layer in the BaTiO3 film.The dielectric properties of BaTiO3 Ag were discussed in detail taking into account the changes in microstructures.     

Platinum colloid catalyzed etchingless gold electroless plating with strong adhesion to polymers

Echingless electroless plating (ELP) process that can produce gold thin film with strong adhesion to various polymer films has been developed. We have found that platinum (Pt) colloidal nanoparticles have excellent catalytic activity for ELP. The Pt colloidal nanoparticles can be immobilized via electrostatic interactions on a substrate simply by dipping it into a Pt colloid. Owing to the excellent catalytic property of the Pt nanoparticles, continuous gold thin films can be produced at room temperature using a simple cyanide-free gold electroless plating solution composed of chloroauric acid and hydrogen peroxide. The process requires no surface modifications for the immobilization of the catalyst, and by simple post-annealing the adhesion of the plated films to various polymer films can be improved by three orders of magnitude in comparison to that of “as-deposited” film. The process developed in this work is expected to be an environment-friendly thin metal film deposition process without the use of toxic and hazardous substances.