这项研究得到为中心的能源纳米，由能源，科学办公室根据奖号DE-SC0001013美国能源部资助的能源前沿研究中心的一部分。我们还要感谢张兆旭博士和杨建华惠普实验室的博士它们对二氧化钛薄膜溅射和折射率测量帮助。

1.准备空白聚二甲基硅氧烷（PDMS）为基材纳米压印模具<ol><li>硅片处理工艺<ol><li>通过用丙酮，甲醇和异丙醇漂洗清洗4英寸的硅晶片。 </li><li>吹干使用氮气枪。 </li><li> （：硫酸，用30％的过氧化氢的混合物3）通过浸泡内15分钟用食人鱼溶液清洗。 </li><li>用去离子水冲洗。使用氮气枪吹干。 </li><li>放置在玻璃干燥器的晶片。添加脱模剂（三氯硅烷）进入干燥器的下降（20滴= 1毫升）。 </li><li>抽空干燥器，直到压力表读数-762​​托，等待5小时。 </li><li>取晶片出来，这已经用脱模剂。 </li></ol></li><li> PDMS薄膜的制备（用作模具在纳米压印） <ol><li>称取将10克硅橡胶基地和1克固化剂。 </li><li>添加它们以相同的玻璃烧杯中。 </li><li>性病r和混合用玻璃棒5分钟。 </li><li>将混合物放入真空干燥器中，直至压力表读数-762​​乇泵出所有夹带的气泡。 </li><li>均匀地散布到他们的处理4英寸硅晶片。 </li><li>烘烤在顶部的真空烘箱中7小时的PDMS晶片在80℃下，以固化的PDMS膜。 </li></ol></li></ol> 2.（从母模复制）准备纳米压印模具<ol><li>旋12滴（20滴= 1毫升）的UV可固化抗蚀剂（15.2％）干净的空白硅晶片上30秒以1,500rpm。 </li><li>小心剥离一块PDMS膜关闭处理的硅晶片。 </li><li>放的PDMS薄膜上的紫外线固化性抗蚀剂，并让它吸收UV抗蚀剂进行5分钟，然后把它剥开。 </li><li>重复2.1-2.3在相同的PDMS膜两次。吸收UV分别抗蚀3分钟和1分钟。 </li><li>将PDMS膜（后三次抵抗紫外线吸收）到硅模具师傅。 </li><li>把它放入用氮气环境的腔室。 </li><li>打开紫外灯，以固化样品5分钟。 </li><li>剥离PDMS膜。固化的紫外线抗蚀剂上的PDMS将保持母模的负图案。 </li><li>利用射频O 2等离子治疗的PDMS模具。 （RF功率：30W，压力：260毫乇，时间：1分钟） </li><li>将PDMS模具在真空室中带脱模剂2小时的一滴（20滴= 1毫升）。 </li></ol> 3.纳米压印图案转印<ol><li>在基片上旋8滴（20滴= 1毫升）的PMMA（996k，3.1％），以在3,500rpm进行压印，50秒。 </li><li>烤它在热板上进行5分钟，在120℃。 </li><li>等待样品冷却下来。 </li><li>旋8滴（20滴= 1毫升）的UV可固化抗蚀剂（3.9％），在同一基板上。 </li><li>放置的PDMS模具（在步骤2中制备的）在样品上（与两个紫外抗蚀剂和聚甲基丙烯酸甲酯）。 </li><li>把它放入用氮气环境的腔室。</li><li>打开的紫外灯固化5分钟。 </li><li>剥离的PDMS模具关闭样品和在PDMS模具的图案被转移到样品。 </li></ol> 4.铬剥离工艺<ol><li>反应离子蚀刻紫外线残留抗蚀剂层和聚甲基丙烯酸甲酯 注：为SOP机器ICP可在https://www.nanocenter.umd.edu/equipment/fablab/sops/etch-07/Oxford%20Chlorine%20Etcher%20SOP.pdf发现<ol><li>登录RIE威达机械。 </li><li>放入空白4英寸硅片。运行清洁配方10分钟。 </li><li>就拿空白硅片出。 </li><li>安装样品上的另一个干净的硅晶片，并加载到机器。 </li><li>运行紫外抗蚀剂蚀刻配方为2分钟（配方在表1中找到）。 </li><li>取样品出来。放入空白4英寸硅片。重新运行清洁配方10分钟（在表1中可以找到）。 </li><li>装载样品清洁硅晶片上并将其加载到机器。 </li><li>运行的PMMA的蚀刻配方（可在表1中可以找到）2分钟。 注意：现在的残留抗蚀剂已经蚀刻和基材暴露。 </li></ol></li><li>铬电子束蒸发<ol><li>登录到电子束蒸发器。 </li><li>加载的Cr金属源和样品放入室中。 </li><li>置的厚度（20 nm），而沉积速率（0.03纳米/秒）。 </li><li>泵送腔室，直到所需的真空（10 -7乇）为止。 </li><li>启动沉积过程。 </li><li>取样品从沉积结束后。 </li></ol></li><li> CR剥离过程<ol><li>沉浸样品在丙酮超声搅拌5分钟。 </li><li>通过用丙酮，甲醇和异丙醇漂洗清洁样品。 注意：铬蒸镀在抗蚀剂将被剥离，并形成一个Cr掩膜对基板蚀刻。 </li></ol></li></ol> 5. 二氧化钛德普osition <ol><li>加载样品。 </li><li>设置参数直流磁控溅射镀膜机<ol><li>使用1.5毫托的室压力，以100sccm Ar流量为130 W·溅射功率</li><li>使用27℃的温度和20 rpm的阶段转动速度。 </li></ol></li><li>启动溅射处理，并停止在所希望的厚度。 </li><li>取样品出来，退火在氧气环境中的TiO 2膜在300℃下3小时。 </li></ol> 6.高对比度光栅刻蚀<ol><li>登录在感应耦合等离子体（ICP）的反应离子蚀刻（RIE）的机器。 </li><li> TiO 2的蚀刻<ol><li>放入空白4英寸硅晶片。 </li><li>启动和运行的洁净配方10分钟（在表1中可以找到）。 </li><li>卸载装载晶圆空白和负载与Cr掩膜样品。 </li><li>设置蚀刻时间。开始TiO 2的蚀刻配方。蚀刻过程中会自动matically停止。 </li><li>卸载样品。 </li></ol></li><li> SiO 2的蚀刻<ol><li>除了 ​​使用SiO 2的蚀刻配方重复步骤5.2。 </li></ol></li></ol> 7.反射测量仪<ol><li>登录并打开测量系统。 </li><li>放置在试样保持器的反射率标准镜子和对准的光路。 </li><li>校准系统为100％的反射率。 </li><li>取下反射镜的标准，然后将HCG。 </li><li>测量HCG的反射率。 </li><li>保存数据并注销测量系统。 </li></ol>

<ol>
	<li>Horne, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Solid+500+Sun+Compound+Concentrator+PV+Design.">A Solid 500 Sun Compound Concentrator PV Design.</a> Photovoltaic Energy Conversion, Conference Record of the 2006 IEEE 4th World Conference on. , 694-697 (2006).</li><li>Guter, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current-matched+triple-junction+solar+cell+reaching+41.1%+conversion+efficiency+under+concentrated+sunlight.">Current-matched triple-junction solar cell reaching 41.1% conversion efficiency under concentrated sunlight.</a> Applied Physics Letters. 94, 223504 (2009).</li><li>Shockley, W., Queisser, H. 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The authors have nothing to disclose.

首先，在TiO 2膜的质量对于HCG的性能非常关键。反射率峰值将更高，如果在TiO 2膜具有较少损耗和表面粗糙度。在TiO 2膜具有更高的折射率也是有利的，因为该光学模式限制将通过在指数更高的对比度，从而可以产生更平坦和更广泛的反射带中的HCG来增强。 第二，在制造误差会对HCG显著影响，应加以避免。在制造中引入的粗糙度会导致更多的光被散射?...

无需移动能量消耗的显著一部分可再生能源现代社会将无法生存。要做到这一点，我们必须找到一种方式的成本比在不久的将来，石油为主的能源更低的收获可再生能源。太阳能是地球上最丰富的可再生能源。尽管很多进展的已在太阳能收集，它仍然是非常具有挑战性的，用石油为基础的能源竞争。提高太阳能电池的效率是最有效的方法来降低的太阳能收集系统的成本之一。 光学透镜和盘的反射器通常用在最浓的光伏（CPV）系统1，实现了高浓度对小面积的太阳能电池的太阳能发电率，所以它是经济上可行的利用昂贵串联多结太阳能电池2中CPV系统，并保持合理的成本的同时。然而，对于大多数非集中光伏系统，其通常需要的太阳能电池的大面积装置，高成本叠层太阳电池不能掺入，尽管它们通常具有更广阔的太阳光谱响应和比更高的总转换效率单结太阳能电池3。 最近，与并行光谱分裂光学器件的帮助下（ 即色散元件），平行光谱分裂光伏技术4使得有可能，类似的或更好的频谱覆盖范围和转换效率，而无需使用昂贵的串联型太阳能电池来实现。太阳光谱可以被分成不同的频带，每个频带可以被吸收并转换为电的专门的单结太阳能电池。以这种方式，昂贵的串联型太阳能电池中CPV系统可通过单结太阳能电池的并行分布来代替•不用对性能的任何折衷。 这是设计本报告中的色散元件可以在反射的CPV系统（它是基于盘反射器），以实现平行的频谱分割为改进太阳能电转换效率和降低的成本施用。多层高对比度光栅（HCG）5用作色散元件通过设计的HCG各层工作作为光学带反射器。的结构和色散元件的参数进行数值优化。此外，高对比度的光栅的制造通过使用电介质色散元件（ 二氧化钛）溅射，纳米压印光刻6和反应离子蚀刻进行了研究和论证。

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>184 SILICONE ELASTOMER KIT</td>
			<td>SYLGARD</td>
			<td></td>
			<td>Polydimethylsiloxane (PDMS)</td>
		</tr>
		<tr>
			<td>4-inch silicon wafer</td>
			<td>Universitywafer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>4-inch fused silica wafer</td>
			<td>Universitywafer</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(methyl methacrylate)</td>
			<td>SIGMA-ALDRICH</td>
			<td align="right">182265</td>
			<td></td>
		</tr>
		<tr>
			<td>UV-curable resist</td>
			<td></td>
			<td></td>
			<td>Nor available on market</td>
		</tr>
		<tr>
			<td>PlasmaLab System 100</td>
			<td>Oxford Instruments</td>
			<td></td>
			<td>ICP IRE machine</td>
		</tr>
		<tr>
			<td>UV curing system for nanoimprint fabrication</td>
			<td></td>
			<td></td>
			<td>Not available on market</td>
		</tr>
		<tr>
			<td>Ocean Optics HR-4000&#160;</td>
			<td>Ocean Optics</td>
			<td>HR-4000</td>
			<td>Spectrometer with normal detector</td>
		</tr>
		<tr>
			<td>Lambda 950 UV / VIS</td>
			<td>PerkinElmer</td>
			<td></td>
			<td>spectrometer with hemisphere intergration detector</td>
		</tr>
		<tr>
			<td>JSM-7001F-LV</td>
			<td>JEOL</td>
			<td></td>
			<td>Field emission SEM</td>
		</tr>
		<tr>
			<td>DC magnetron sputtering machine</td>
			<td></td>
			<td></td>
			<td>Equipment is in HP labs, who helped us to sputter the TiO2</td>
		</tr>
		<tr>
			<td>Metal e-beam evaporator</td>
			<td>Temescal</td>
			<td>BJD-1800</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of high contrast gratings for the spectrum splitting dispersive element in a concentrated photovoltaic system

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

图1示出了色散元件（多层高对比度光栅（HCG））的一个集中式光伏系统的实施。太阳光线首先由主反射镜反射并撞击反射色散元件，其中该光束被反射并分成不同波长的不同的频带上。每个频带将撞击在目标位置的太阳电池阵列的最佳吸收并转化成电力上。这里的关键系统是设计和实现色散元件，它是由HCG的多层的。 图2示出了用于在分散元件的每...

Watch this Scientific Journal Video about Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System at JoVE.com

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

制造高对比度光栅的频谱分割色散元件的聚光光伏系统

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

fabrication-high-contrast-gratings-for-spectrum-splitting-dispersive

Research

JoVE Journal

Engineering

10.6K 次观看.  University of Sothern California. The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance. 

视频: Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

Electron Channeling Contrast Imaging for Rapid III-V Heteroepitaxial Characterization

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging (ECCI) in a scanning electron microscope (SEM). ECCI allows for imaging of defects and crystallographic features under specific diffraction conditions, similar to that possible via plan-view transmission electron microscopy (PV-TEM). A particular advantage of the ECCI technique is that it requires little to no sample preparation, and indeed can use large area, as-produced samples, making it a considerably higher throughput characterization method than TEM. Similar to TEM, different diffraction conditions can be obtained with ECCI by tilting and rotating the sample in the SEM. This capability enables the selective imaging of specific defects, such as misfit dislocations at the GaP/Si interface, with high contrast levels, which are determined by the standard invisibility criteria. An example application of this technique is described wherein ECCI imaging is used to determine the critical thickness for dislocation nucleation for GaP-on-Si by imaging a range of samples with various GaP epilayer thicknesses. Examples of ECCI micrographs of additional defect types, including threading dislocations and a stacking fault, are provided as demonstration of its broad, TEM-like applicability. Ultimately, the combination of TEM-like capabilities &#8211; high spatial resolution and richness of microstructural data &#8211; with the convenience and speed of SEM, position ECCI as a powerful tool for the rapid characterization of crystalline materials.

The use of electron channeling contrast imaging in a scanning electron microscope to characterize defects in III-V/Si heteroexpitaxial thin films is described. This method yields similar results to plan-view transmission electron microscopy, but in significantly less time due to lack of required sample preparation.

电子通道造影的快速III-V异质特征

Misfit dislocations in heteroepitaxial layers of GaP grown on Si(001) substrates are characterized through use of electron channeling contrast imaging ...

科研

工程学

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

能量色散X射线断层摄影术对个人纳米3D元素映射

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

写布拉格光栅在多核纤维

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

Fabrication of Fully Solution Processed Inorganic Nanocrystal Photovoltaic Devices

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal inks. For the photoactive absorber layer, colloidal CdTe and CdSe nanocrystals (3-5 nm) are synthesized using an inert hot injection technique and cleaned with precipitations to remove excess starting reagents. Similarly, gold nanocrystals (3-5 nm) are synthesized under ambient conditions and dissolved in organic solvents. In addition, precursor solutions for transparent conductive indium tin oxide (ITO) films are prepared from solutions of indium and tin salts paired with a reactive oxidizer. Layer-by-layer, these solutions are deposited onto a glass substrate following annealing (200-400 &#176;C) to build the nanocrystal solar cell (glass/ITO/CdSe/CdTe/Au). Pre-annealing ligand exchange is required for CdSe and CdTe nanocrystals where films are dipped in NH4Cl:methanol to replace long-chain native ligands with small inorganic Cl- anions. NH4Cl(s) was found to act as a catalyst for the sintering reaction (as a non-toxic alternative to the conventional CdCl2(s) treatment) leading to grain growth (136&#177;39 nm) during heating. The thickness and roughness of the prepared films are characterized with SEM and optical profilometry. FTIR is used to determine the degree of ligand exchange prior to sintering, and XRD is used to verify the crystallinity and phase of each material. UV/Vis spectra show high visible light transmission through the ITO layer and a red shift in the absorbance of the cadmium chalcogenide nanocrystals after thermal annealing. Current-voltage curves of completed devices are measured under simulated one sun illumination. Small differences in deposition techniques and reagents employed during ligand exchange have been shown to have a profound influence on the device properties. Here, we examine the effects of chemical (sintering and ligand exchange agents) and physical treatments (solution concentration, spray-pressure, annealing time and annealing temperature) on photovoltaic device performance.

This protocol describes the synthesis and solution deposition of inorganic nanocrystals layer by layer to produce thin film electronics on non-conductive surfaces. Solvent-stabilized inks can produce complete photovoltaic devices on glass substrates via spin and spray coating following post-deposition ligand exchange and sintering.

全面解决方案处理的无机纳米晶体光伏器件的制造

We demonstrate a method for the preparation of fully solution processed inorganic solar cells from a spin and spray coating deposition of nanocrystal ...

Recombination Dynamics in Thin-film Photovoltaic Materials via Time-resolved Microwave Conductivity

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials such as organo-lead halide perovskites is presented. The perovskite film thickness and absorption coefficient are initially characterized by profilometry and UV-VIS absorption spectroscopy. Calibration of both laser power and cavity sensitivity is described in detail. A protocol for performing Flash-photolysis Time Resolved Microwave Conductivity (TRMC) experiments, a non-contact method of determining the conductivity of a material, is presented. A process for identifying the real and imaginary components of the complex conductivity by performing TRMC as a function of microwave frequency is given. Charge carrier dynamics are determined under different excitation regimes (including both power and wavelength). Techniques for distinguishing between direct and trap-mediated decay processes are presented and discussed. Results are modelled and interpreted with reference to a general kinetic model of photoinduced charge carriers in a semiconductor. The techniques described are applicable to a wide range of optoelectronic materials, including organic and inorganic photovoltaic materials, nanoparticles, and conducting/semiconducting thin films.

A Time Resolved Microwave Conductivity technique for investigating direct and trap-mediated recombination dynamics and determining carrier mobilities of thin film semiconductors is presented here.

通过时间分辨微波电导率重组动力学薄膜光伏材料

A method for investigating recombination dynamics of photo-induced charge carriers in thin film semiconductors, specifically in photovoltaic materials ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Challenges in Rheological Characterization of Highly Concentrated Suspensions &amp;#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

挑战流变特性高度集中悬架 - 为例进行丝网印刷银浆

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia (YSZ) Scaffolds by In Situ Carbon Templating Xerogels

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) scaffolds with tunable specific surface areas up to 80 m2&#183;g-1. An aqueous solution of a zirconium salt, yttrium salt, and glucose is mixed with propylene oxide (PO) to form a gel. The gel is dried under ambient conditions to form a xerogel. The xerogel is pressed into pellets and then sintered in an argon atmosphere. During sintering, a YSZ ceramic phase forms and the organic components decompose, leaving behind amorphous carbon. The carbon formed in situ serves as a hard template, preserving a high surface area YSZ nanomorphology at sintering temperature. The carbon is subsequently removed by oxidation in air at low temperature, resulting in a porous, nanostructured YSZ scaffold. The concentration of the carbon template and the final scaffold surface area can be systematically tuned by varying the glucose concentration in the gel synthesis. The carbon template concentration was quantified using thermogravimetric analysis (TGA), the surface area and pore size distribution was determined by physical adsorption measurements, and the morphology was characterized using scanning electron microscopy (SEM). Phase purity and crystallite size was determined using X-ray diffraction (XRD). This fabrication approach provides a novel, flexible platform for realizing unprecedented scaffold surface areas and nanomorphologies for ceramic-based electrochemical energy conversion applications, e.g. solid oxide fuel cell (SOFC) electrodes.

High Temperature Fabrication of Nanostructured Yttria-Stabilized-Zirconia YSZ Scaffolds by In Situ Carbon Templating Xerogels

A protocol for fabricating porous, nanostructured yttria-stabilized-zirconia (YSZ) scaffolds at temperatures between 1,000 &#176;C and 1,400 &#176;C is presented.

通过纳米氧化钇稳定的二氧化锆（YSZ）的支架的高温加工<em&gt;原位</em&gt;碳模板干凝胶

We demonstrate a method for the high temperature fabrication of porous, nanostructured yttria-stabilized-zirconia (YSZ, 8 mol% yttria - 92 mol% zirconia) ...

Detecting the Water-soluble Chloride Distribution of Cement Paste in a High-precision Way

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a high-precision chloride profile. Firstly, paste specimens are molded, cured, and exposed to cyclic wet-dry conditions. Then, powder samples at different specimen depths are grinded when the exposure age is reached. Finally, the water-soluble chloride content is detected using a silver nitrate titration method, and chloride profiles are plotted. The key to improving the accuracy of the chloride distribution along the depth is to exclude the error in the powderization, which is the most critical step for testing the distribution of chloride. Based on the above concept, the grinding method in this protocol can be used to grind powder samples automatically layer by layer from the surface inward, and it should be noted that a very thin grinding thickness (less than 0.5 mm) with a minimum error less than 0.04 mm can be obtained. The chloride profile obtained by this method better reflects the chloride distribution in specimens, which helps researchers to capture the distribution features that are often overlooked. Furthermore, this method can be applied to studies in the field of cement-based materials, which require high chloride distribution accuracy.

A protocol for obtaining a water-soluble chloride profile by using a high precision milling method is presented.

高精度水泥浆水溶氯分布的检测

To improve the accuracy of the chloride distribution along the depth of cement paste under cyclic wet-dry conditions, a new method is proposed to obtain a ...

Method for Recording Broadband High Resolution Emission Spectra of Laboratory Lightning Arcs

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional camera film methods and then digital camera technology, from which several important characteristics have been derived. However, such work has always been limited due to the inherently random and non-repeatable nature of natural lightning events in the field. Recent developments in lightning test facilities now allow the reproducible generation of lightning arcs within controlled laboratory environments, providing a test bed for the development of new sensors and diagnostic techniques to understand lightning mechanisms better. One such technique is a spectroscopic system using digital camera technology capable of identifying the chemical elements with which the lightning arc interacts, with these data then being used to derive further characteristics. In this paper, the spectroscopic system is used to obtain the emission spectrum from a 100 kA peak, 100 &#181;s duration lightning arc generated across a pair of hemispherical tungsten electrodes separated by a small air gap. To maintain a spectral resolution of less than 1 nm, several individual spectra were recorded across discrete wavelength ranges, averaged, stitched, and corrected to produce a final composite spectrum in the 450 nm (blue light) to 890 nm (near infrared light) range. Characteristic peaks within the data were then compared to an established publicly available database to identify the chemical element interactions. This method is readily applicable to a variety of other light emitting events, such as fast electrical discharges, partial discharges, and sparking in electrical equipment, apparatus, and systems.

Emission spectroscopy techniques have traditionally been used to analyze inherently random lightning arcs occurring in nature. In this paper, a method developed to obtain the emission spectroscopy from reproducible lightning arcs generated within a laboratory environment is described.

记录实验室闪电弧宽带高分辨率发射光谱的方法

Lightning is one of the most common and destructive forces in nature and has long been studied using spectroscopic techniques, first with traditional ...

Flow-assisted Dielectrophoresis: A Low Cost Method for the Fabrication of High Performance Solution-processable Nanowire Devices

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of nanowires. DEP is used for nanowire analysis, characterization, and for solution-based fabrication of semiconducting devices. The method works by applying an alternating electric field between metallic electrodes. The nanowire formulation is then dropped onto the electrodes which are on an inclined surface to create a flow of the formulation using gravity. The nanowires then align along the gradient of the electric field and in the direction of the liquid flow. The frequency of the field can be adjusted to select nanowires with superior conductivity and lower trap density. 
In this work, flow-assisted DEP is used to create nanowire field effect transistors. Flow-assisted DEP has several advantages: it allows selection of nanowire electrical properties; control of nanowire length; placement of nanowires in specific areas; control of orientation of nanowires; and control of nanowire density in the device. 
The technique can be expanded to many other applications such as gas sensors and microwave switches. The technique is efficient, quick, reproducible, and it uses a minimal amount of dilute solution making it ideal for the testing of novel nanomaterials. Wafer scale assembly of nanowire devices can also be achieved using this technique, allowing large numbers of samples for testing and large-area electronic applications.

In this paper, flow assisted dielectrophoresis is demonstrated for the self-assembly of nanowire devices. The fabrication of a silicon nanowire field effect transistor is shown as an example.

流动辅助介: 一种低成本的制备高性能溶液可纳米线器件的方法

Flow-assisted dielectrophoresis (DEP) is an efficient self-assembly method for the controllable and reproducible positioning, alignment, and selection of ...