SiO2和ZrO2薄膜光学性能的椭偏光谱测量

用溶胶-凝胶工艺在碱性催化条件下,采用旋转镀膜法在K9玻璃上分别制备了性能稳定的单层SiO2薄膜与单层ZrO2薄膜。用反射式椭圆偏振光谱仪测试了薄膜的椭偏参数,并用Cauchy模型对椭偏参数进行数据拟合,获得了溶胶-凝胶SiO2与ZrO2薄膜在300~800 nm波段的色散关系。用紫外-可见分光光度计测量了薄膜的透射率,并与用椭偏仪换算出来的结果相比较;用原子力显微镜观察了薄膜的表面微结构,并讨论表面微结构与薄膜光学常数之间的关系。分析结果表明,Cauchy模型能较好的描述溶胶-凝胶薄膜的光学性能,较详细的得到了薄膜的折射率,消光系数等光学常数随波长λ的变化规律;薄膜光学常数的大小与薄膜的微结构有关。     

退火温度对二氧化钒薄膜红外

针对提高用溶胶–凝胶法制备的VO 薄膜的红外透过率的问题,提出了制备时的最佳退火温度。简 要介绍了用无机溶胶凝胶法制备VO 薄膜的过程,对制备的VO 薄膜进行了差示扫描量热(DSC)、X射线电子能谱仪 (XPS)测试,分析了VO 薄膜的成分及相变温度。根据瑞利–高斯散射公式,通过散射截面与粒子密度计算和不同退火 温度下薄膜透过率的测试,重点讨论了退火温度、晶粒尺寸和红外透射率三者的关系。     

高功率激光宽谱增透膜的研究

为满足高功率激光抽运中氙灯及其防护隔板玻璃宽谱增透的要求,采用提拉镀膜法在K9基片上通过溶胶-凝胶工艺镀制有机硅-SiO2双层宽谱增透膜系.在实验的基础上讨论了有机硅-SiO2双层膜系中膜厚的搭配以及膜系的宽谱增透特性.实验研究表明通过合理的膜层搭配和对镀膜参量的有效调控,有机硅-SiO2双层宽谱增透膜系在376～927nm连续波段内具有透射率大于98%的增透效果,激光损伤阈值大于20J/cm2(1064nm,4ns),且性能稳定,完全满足氙灯及其防护隔板上宽谱增透膜的要求.     

金属离子掺杂的TiO_2-SiO_2增透膜的制备及性能

为了得到高增透的TiO2-SiO2薄膜,采用sol-gel法制备了金属离子掺杂的TiO2-SiO2薄膜,并对其透射光谱和薄膜厚度进行了表征,研究了退火温度及不同金属离子掺杂(Al3+、Fe3+和Zn2+)对TiO2-SiO2薄膜增透性能的影响。结果表明:Al3+、Fe3+可提高薄膜在可见光波段的增透性,其中,掺杂Al3+的摩尔分数为0.4%的薄膜,未经退火处理的增透性能最佳(透射率可达98%)。掺杂Fe3+使薄膜的截止波长红移量最大,约为14nm。     

利用介质膜特性矩阵讨论介质膜的增透条件

利用介质膜特型矩阵系统讨论了设计增透型介质膜的条件。本文主要从介质膜反射和透射的角度出发 ,利用反射率和透射率的关系 ,运用数学方法详细地讨论了实现介质膜增透的条件。以此理论为依据 ,可对不同介质材料或多层介质薄膜进行分析设计。     

钛宝石强激光负载的有机硅复合凝胶增透膜研究

以硅酸四乙酯(TEOS)和甲基三乙氧基硅烷(MTEOS)为前驱材料，用溶胶-凝胶(sol-gel)方法在钛宝石表面制备得到均匀性良好且具有高激光损伤阈值的有机硅复合凝胶增透膜。膜层在钛宝石激光器输出波段(750～850nm)的增透效果显著，其平均透过率超过98．6％；激光破坏阈值为2．2J／cm^2(800nm，300ps)；膜层表面均匀性达到激光波面的要求，在皮秒、飞秒超短脉冲高功率激光领域具有应用价值。溶胶的性能测试结果表明，溶胶粘度和成膜折射率均随溶液中CH3SiO1.5溶胶体含量的增加而增大，而膜层折射率受烘烤温度影响较小。     

退火温度对二氧化钒薄膜红外透过率的影响

针对提高用溶-胶凝胶法制备的VO2薄膜的红外透过率的问题,提出了制备时的最佳退火温度.简要介绍了用无机溶胶凝胶法制备VP2薄膜的过程,对制备的VO2薄膜进行了差示扫描量热(DSC),X射线电子能谱仪(XPS)测试,分析了VO2薄膜的成分及相交温度.根据瑞利-高斯散射公式,通过散射截面与粒子密度计算和不同退火温度下薄膜透过率的测试,重点讨论了退火温度、晶粒尺寸和红外透射率三者的关系.     

复合热释电薄膜红外探测器的研究

热绝缘结构是热释电红外探测器的关键技术之一."复合热释电薄膜红外探测器"是用多孔SiO2薄膜来绝热的,这种无空气隙的新型结构被认为具有更高的机械强度和可靠性.采用溶胶-凝胶技术制备了热导率极低的多孔SiO2薄膜,用金属有机物热分解法制备了优质的铁电薄膜,实现了"复合热释电薄膜"热绝缘结构,获得的星探测率最大值达9.3×107cm.Hz1/2/W.通过快速热处理工艺的采用,提高薄膜一次成膜厚度的研究,改善了薄膜制备与微电路工艺的兼容性.研究了多孔膜厚度、孔径分布与探测率的关系,探讨了镍酸镧(LNO)薄膜作为缓冲层、红外吸收层和上电极的多功能作用.结果表明:孔径分布小的多孔膜有利于探测器性能的提高.在此结构中,存在热性能和电性能的折中问题,多孔膜厚度有一个临界值.LNO薄膜的引入,可以改善性能、简化结构和工艺.讨论了低温铁电薄膜的制备和性能,以及与微电路实现单片集成等问题.     

傅里叶合成法设计渐变折射率薄膜

傅里叶合成方法是一种可以根据期望的光谱特性曲线设计渐变折射率薄膜的方法.叙述了该方法的原理和Q函数的选择.介绍了修正方法使设计膜层折射率在可获得薄膜材料折射率范围内和把膜层匹配到入射介质和基底两端界面的技术.并用该方法设计ZnSe基底3～12μm红外增透渐变折射率薄膜,在设计波段平均透射率达到95%.最后对该方法作了相关评论.     

陶瓷材料

0210304钙钛矿型铁电薄膜的溶胶-凝胶法制备〔刊〕/王歆//压电与声光.-2002,24(1).-57～60(L) 介绍了溶胶-凝胶薄膜制备法,研究了浸涂法和旋涂法对薄膜质量的影响因素和控制理论,阐述薄膜干燥法与裂纹形成机理,基片因素对晶体结构的影响等问题。讨论溶胶-凝胶法制膜过程中,铁电薄膜全钙钛矿的形成和晶粒的定向生长。参10     

Additive Manufacturing of 3D Aerogels and Porous Scaffolds: A Review

Aerogels are highly porous structures produced by replacing the liquid solvent of a gel with air without causing a collapse in the solid network. Unlike conventional fabrication methods, additive manufacturing (AM) has been applied to fabricate 3D aerogels with customized geometries specific to their applications, designed pore morphologies, multimaterial structures, etc. To date, three major AM technologies (extrusion, inkjet, and stereolithography) followed by a drying process have been proposed to additively manufacture 3D functional aerogels. 3D-printed aerogels and porous scaffolds showed great promise for a variety of applications, including tissue engineering, electrochemical energy storage, controlled drug delivery, sensing, and soft robotics. In this review, the details of steps included in the AM of aerogels and porous scaffolds are discussed, and a general frame is provided for AM of those. Then, the different postprinting processes are addressed to achieve the porosity (after drying); and mechanical strength, functionality, or both (after postdrying thermal or chemical treatments) are provided. Furthermore, the applications of the 3D-printed aerogels/porous scaffolds made from a variety of materials are also highlighted. The review is concluded with the current challenges and an outlook for the next generation of 3D-printed aerogels and porous scaffolds.     

Ambient‐Dried, 3D‐Printable and Electrically Conducting Cellulose Nanofiber Aerogels by Inclusion of Functional Polymers

This study presents a novel, green, and efficient way of preparing crosslinked aerogels from cellulose nanofibers (CNFs) and alginate using non‐covalent chemistry. This new process can ultimately facilitate the fast, continuous, and large‐scale production of porous, light‐weight materials as it does not require freeze‐drying, supercritical CO₂ drying, or any environmentally harmful crosslinking chemistries. The reported preparation procedure relies solely on the successive freezing, solvent‐exchange, and ambient drying of composite CNF‐alginate gels. The presented findings suggest that a highly‐porous structure can be preserved throughout the process by simply controlling the ionic strength of the gel. Aerogels with tunable densities (23–38 kg m^?3) and compressive moduli (97–275 kPa) can be prepared by using different CNF concentrations. These low‐density networks have a unique combination of formability (using molding or 3D‐printing) and wet‐stability (when ion exchanged to calcium ions). To demonstrate their use in advanced wet applications, the printed aerogels are functionalized with very high loadings of conducting poly(3,4‐ethylenedioxythiophene):tosylate (PEDOT:TOS) polymer by using a novel in situ polymerization approach. In‐depth material characterization reveals that these aerogels have the potential to be used in not only energy storage applications (specific capacitance of 78 F g^?1), but also as mechanical‐strain and humidity sensors.     

Collagen/hydroxyapatite composite materials with desired ceramic properties

Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5?g/cm(3) while the porosity varies from 96.5% down to 27.5%.     

多孔硅的干燥方法

研究了多孔硅的阴极还原表面处理技术,通过该技术获得了表面平滑度良好、稳定度高、抗压强度高和耐高温性能好且在空气中可以长期干燥保存的多孔硅样品.在其表面上可以进行光刻、镀金等工艺,因此,可应用于制作器件甚至电路集成     

Mixed Aerogels from Au and CdTe Nanoparticles

Mixed metal–semiconductor nanocrystal aerogels are fabricated, which are light‐emitting and highly porous macroscopic monoliths. Thiol‐stabilized CdTe and Au nanoparticles from aqueous synthesis act as building blocks for the hybrid material. The Au colloids undergo a surface‐modification to enhance the particle stability and achieve thiol functionalities. A photochemical treatment is applied for the gelation process which is found to be reversible by subsequent addition of thiol molecules. Via supercritical drying aerogels are formed. The variation of the initial CdTe to Au nanoparticle ratio permits a facile tuning of the content and the properties of the resulting aerogels. The obtained structures were characterized by means of optical spectroscopy, electron microscopy, elemental analysis, and nitrogen physisorption.     

Design,development and control of a portable laboratory for the chili drying process study

Agricultural products such as chilies generally require drying for preservation. Traditionally, the chili drying process has been accomplished by burning fossil fuels in ovens or by open air drying. However, this process leads to severe losses in the quality and quantity of the final product. In this paper, a portable laboratory has been designed, developed and controlled using a mechatronic design philosophy in order to facilitate the chili drying process study. This portable laboratory can simulate different drying conditions under a controlled environment in order to find the best drying parameters for different kinds of chilies. Their computer based intelligence can monitor and control temperature, humidity, air flow, electric current and weight through a graphical user interface (GUI). The modeling and control technique of the system is described in detail. Simulation results using the mathematical model and experimental results under different drying conditions are presented to demonstrate the high performance of the portable laboratory and its great potential.     

Lightweight and Anisotropic Porous MWCNT/WPU Composites for Ultrahigh Performance Electromagnetic Interference Shielding

Lightweight, flexible and anisotropic porous multiwalled carbon nanotube (MWCNT)/water‐borne polyurethane (WPU) composites are assembled by a facile freeze‐drying method. The composites contain extremely wide range of MWCNT mass ratios and show giant electromagnetic interference (EMI) shielding effectiveness (SE) which exceeds 50 or 20 dB in the X‐band while the density is merely 126 or 20 mg cm^?3, respectively. The relevant specific SE is up to 1148 dB cm³ g^?1, greater than those of other shielding materials ever reported. The ultrahigh EMI shielding performance is attributed to the conductivity of the cell walls caused by MWCNT content, the anisotropic porous structures, and the polarization between MWCNT and WPU matrix. In addition to the enhanced electrical properties, the composites also indicate enhanced mechanical properties compared with porous WPU and CNT architectures.     

Conducting polyheterocycle composites based on porous hosts

Conducting composites based on porous substrates (cotton fiber, non-woven polypropylene mat and porous crosslinked polystyrene) have been prepared by a two step imbibition technique. First, the substrate was imbibed with a solution of monomer (pyrrole or bithiophene) in acetonitrile, followed by partial drying. Subsequently, the substrate was again imbibed, this time with an oxidant dissolved in a suitable solvent. The polymerization of the monomer inside the host in the presence of the oxidant and the doping of the polymer with the oxidant leads to the conducting composite. The highly hydrophobic and porous crosslinked polystyrene, prepared by the concentrated emulsion polymerization method, is the most efficient. The solvent employed for the oxidant plays a major role. A FeCl₃-methanol system and porous crosslinked polystyrene lead to conductivities of polythiophene and polypyrrole based composites of 3.63 and 0.65 S/cm, respectively. Copper perchlorate and iron perchlorate are also suitable oxidants. The environmental and thermal stabilities of polypyrrole based composites are lower than those of polythiophene based composites. The thermal stability of polypyrrole based composites can be enhanced by including a small amount of an organic antioxidant, such as amides or substituted phenols, in the composite.     

Baby Diaper‐Inspired Construction of 3D Porous Composites for Long‐Term Lithium‐Ion Batteries

In this paper, by using the superabsorbent polymers (SAPs) from baby diaper, the 3D porous composites decorated with NiO and Ni nanoparticles (NNSCs) have been prepared via a facile dissolving‐freeze drying and subsequent annealing reactions. The porous carbon matrix (PCM) derived from the SAPs also provides a continuous highly conductive network to facilitate the fast charge transfer and form a stable solid electrolyte interface film. Furthermore, NNSC can exhibit the high specific capacity and excellent cycle performance as anode materials for lithium‐ion batteries. And more importantly, employing the PCM derived from baby diaper offers a green approach for other energy storage materials.     

Additive-free organic solar cells with enhanced efficiency enabled by unidirectional printing flow of high shear rate

High-performance OSCs prepared by scalable techniques without additives are highly desirable because residual additives may cause gradual deterioration of the photoactive-layer morphology and device performance. Printing flows with high shear rate have the potential to replace additives by inducing higher degree of ordered stacking and crystallinity of organic molecules, as well as favorable phase separation. Here, PTQ10:Y6 organic solar cells (OSCs) without any additives were fabricated by a scalable and robust processing approach termed as soft porous blade printing (SPBP). The fluid flow and drying process of the wet films made by SPBP, blade coating and spin coating are visualized by high speed imaging, which reveals that the blade coating and SPBP introduce unidirectional flow while the wet film interference pattern of spin coating is irregular and random. The simplified flow model of SPBP suggests that the shear rate could be as high as ~1000 s⁻¹. The additive-free SPBP produces photoactive-layer with adequate morphology, which could be attributed to three intrinsic properties of SPBP: very high shear rate, flow assisted crystallizations induced by microstructures of the soft porous blade, and numerous nucleation sites generated as the liquid contact line follows the motion of the blade. The additive-free SPBP device demonstrates weaker charge recombination, higher and more balanced charge transport, and consequently better device performance than the spin-coated and blade-coated devices with 0.25 vol% 1,8-diioctane (DIO). SPBP achieved power conversion efficiency (PCE) of 16.45%, which is higher than those of spin-coated and blade-coated counterparts doped with DIO.