中国材料研究学会 · web viewthe research was reported in applied materials and interfaces....

*E-Material

*Metal Alloy

*Organic & Polymer

*Composite Materials

*Practical Application

*Tech News & New Tech

Vol.78,2015

MCanxixun * Information

MCanxixun Information and News Service

Contents

Tech News & New Tech（技术前沿）.....................................................................3Laser-patterning technique turns metals into supermaterials.............................................................................3激光造型技术可将金属变成超级材料....................................................................................................4

2-D metamaterial surface manipulates light.......................................................................................................5二维超材料表面操纵光............................................................................................................................6

Honeybee hive sealant promotes hair growth in mice........................................................................................6蜜蜂蜂巢密封胶可促进老鼠毛发生长....................................................................................................7

Metal Alloy（金属合金）........................................................................................7Improved Powder Metallurgy superalloy developed at ONERA.......................................................................7法国航空航天实验室研发出改良的粉末冶金高温合金........................................................................8

Scottish steel market set for expansion..............................................................................................................9苏格兰钢铁市场准备扩张......................................................................................................................10

Composite Materials（复合材料）.......................................................................10High-temp composite replaces titanium on Nasa’s Shuttle successor..............................................................10

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MCanxixun Information and News Service

Mcanxixun * Information

美国宇航局用高温复合代替钛..............................................................................................................10Composite wrap being used to repair metal pipes............................................................................................11用来修补金属管道的复合材料包装......................................................................................................11

Practical Application（实际应用）.......................................................................12Zinc-oxide materials tapped for tiny energy harvesting devices......................................................................12为小型能量收集装置开发的氧化锌材料..............................................................................................13

Atomic placement of elements counts for strong concrete...............................................................................15元素的分子位置对高强混凝土十分重要..............................................................................................16

Wearable sensor clears path to long-term EKG, EMG monitoring..................................................................17新型可穿戴传感器可长期监测心电图和肌电图..................................................................................18

Crush those clinkers while they’re hot.............................................................................................................19在熟料高温时粉碎它们..........................................................................................................................20

Organic & Polymer（有机高分子材料）................................................................21Catalyst process uses light for rapid polymerization........................................................................................21用光催化过程实现快速聚合..................................................................................................................22

Solar cell polymers with multiplied electrical output.......................................................................................22新型太阳能电池聚合物增加电量输出..................................................................................................24

Solvay's New Xydar LCP Resin Meets Demands of High-Speed Surface Mount Connectors........................25索尔维集团的新型Xydar LCP树脂材料可用于高速表面安装连接器...............................................25

Solving an organic semiconductor mystery.....................................................................................................26解开有机半导体性能之谜......................................................................................................................27

E-Material（电子材料）.......................................................................................28Researchers develop multiferroic materials, devices integrated with silicon chips..........................................28研究人员研发了可集成到硅片上的多铁材料与设备..........................................................................29

Laser-induced graphene “super” for electronics..............................................................................................30激光诱导石墨烯对电子工业的重要性..................................................................................................31

Single-photon emission enhancement..............................................................................................................33单光子发射增强......................................................................................................................................34

Rice-sized laser bodes well for quantum computing........................................................................................36米粒大小的激光的量子计算应用前景良好..........................................................................................37

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Tech News & New Tech（技术前沿）Laser-patterning technique turns metals into supermaterials

A femtosecond laser created detailed hierarchical structures in the metals, as shown in this SEM image of the platinum surface. Image: The Guo Lab/Univ. of Rochester

By zapping ordinary metals with femtosecond laser pulses researchers from the Univ. of Rochester have created extraordinary new surfaces that efficiently absorb light, repel water and clean themselves. The multifunctional materials could find use in durable, low maintenance solar collectors and sensors.

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"This is the first time that a multifunctional metal surface is created by lasers that is superhydrophobic (water repelling), self-cleaning, and highly absorptive," said Chunlei Guo, a physicist at the Institute of Optics at the Univ. of Rochester who made the new surfaces with his colleague and fellow Univ. of Rochester researcher Anatoliy Vorobyev. The researchers describe the laser-patterned surfaces in an article published in the Journal of Applied Physics.

Enhanced light absorption will benefit technologies that require light collection, such as sensors and solar power devices, while superhydrophobicity will make a surface rust-resistant, anti-icing and anti-biofouling, all of which could help make such devices more robust and easier to maintain, Guo said. The superhydrophobic surfaces can also clean themselves, since water droplets repelled from the surface carry away dust particles very efficiently.

The researchers created the surfaces by zapping platinum, titanium and brass samples with extremely short femtosecond laser pulses that lasted on the order of a millionth of a billionth of a second. "During its short burst the peak power of the laser pulse is equivalent to that of the entire power grid of North America," Guo said.

These extra-powerful laser pulses produced microgrooves, on top of which densely populated, lumpy nanostructures were formed. The structures essentially alter the optical and wetting properties of the surfaces of the three metals, turning the normally shiny surfaces velvet black (very optically absorptive) and also making them water repellent.

Most commercially used hydrophobic and high optical absorption materials rely on chemical coatings that can degrade and peel off over time, said Guo. Because the nano- and microstructures created by the lasers are intrinsic to the metal, the properties they confer should not deteriorate, he said.

The hydrophobic properties of the laser-patterned metals also compare favorably with a famous non-stick coating. "Many people think of Teflon as a hydrophobic surface, but if you want to get rid of water from a Teflon surface, you will have to tilt the surface to nearly 70 degrees before the water can slide off," Guo said. "Our surface has a much stronger hydrophobicity and requires only a couple of degrees of tilt for water to slide off."

Guo and his colleagues have a lot of experience changing the properties of materials with lasers. A couple of years ago, they used lasers to create a superhydrophilic (water attracting) surface that was so strong that water ran uphill against gravity. "After that, we were motivated to create the counterpart technology, making a surface to repel water," Guo said.

The team has plans to work on creating multifunctional effects on other materials, such as semiconductors and dielectrics. The multifunctional effects should find a wide range of applications such as making better solar energy collectors.

Source: American Institute of Physics

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激光造型技术可将金属变成超级材料

飞秒激光可在金属中创建详细的层次结构，如在以上铂表面的扫描电镜图像所示。图片提供：罗彻斯特大学/ Guo实验室。

罗彻斯特大学的研究人员通过将普通金属与飞秒激光脉冲结合，创造了非凡的新表面，使其拥有有效地吸收光线、超疏水和自我清洁的能力。这种多功能材料可以应用于耐用、低维护太阳能收集器和传感器中。

罗彻斯特大学光学研究所的物理学家郭春雷（音译）表示，“这是第一次通过激光创建的一个多功能金属表面，具备疏水性(水排斥)、自洁性和高度吸收性，”他与他的同事和罗彻斯特大学的研究员Anatoliy Vorobyev一同创造出了这一表面。研究人员将描述该激光制造表面的文论刊载于《应用物理杂志》（the Journal of Applied Physics）。

郭表示，增强光吸收的能力将对例如传感器和太阳能设备这些需要光收集的技术有利，而超疏水能力将使表面防锈、防结冰和防污，所有这些都可以使这些设备更结实、更容易维护。疏水性表面还可以自我清洁，因为从超疏水表面反弹的水滴会带走灰尘颗粒这方面非常有效。

研究人员使用超高能且超短的激光脉冲来改变铂、钛和铜等金属样品的表面，这种飞秒激光脉冲持续兆分之一秒的时间。郭表示，“在其短暂的持续时间内，功率峰值可以达到与整个北美电网功率相当的水平。”

这种技术可以在金属表面创造出密集的、纳米尺度结构组成的复杂图案。这种结构本质上改变了这三种金属表面的光学和润湿特性，把正常的闪亮的表面变成黑色天鹅绒(光吸收性很强)，也使其变得防水。

郭春雷表示，目前商业化应用最多的疏水性和高光吸收的材料都依赖于化学涂层，随着时间的推进会降解、剥离。激光在金属上创造的结构本质上是材料表面的一部分，这意味着它们不会被“擦掉”，他说。

激光制造的金属的疏水性能也优于著名的不粘涂层。“很多人认为聚四氟乙烯是疏水表面，但是如果你想摆脱聚四氟乙烯表面的水，你就不得不倾斜接近 70度才能让水滑掉，”郭春雷表示。“我们创造的表面疏水性强得多，只需要倾斜几度水就滑掉了。”

郭和他的同事们对于改变材料激光的特性有很多经验。几年前，他们曾使用激光来创建一个超亲水(水吸引)表面，强大到水可以对抗重力向上爬坡。郭春雷说，“在那之后，我们积极创造相反的技术，使表面排斥水”。

研究团队计划用其他材料（如半导体和绝缘体）创建多功能效果。多功能的效果应该得到一个广泛的应用，例如用于创造更好的太阳能收集器。

资料来源：美国物理研究所

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2-D metamaterial surface manipulates light

On the left, circularly polarized light is converted to a linearly polarized wave upon reflection in a metasurface-based quarter-wave plate. On the right, a top-view FESEM image of the fabricated nanostructure showing the nanorod array. (Bottom scale bar - 400 nm. Top scale bar – 100 nm). Image: Penn State Univ.

A single layer of metallic nanostructures has been designed, fabricated and tested by a team of Penn State Univ. electrical engineers that can provide exceptional capabilities for manipulating light. This engineered surface, which consists of a periodic array of strongly coupled nanorod resonators, could improve systems that perform optical characterization in scientific devices, sensing or satellite communications.

"We have designed and fabricated a waveplate that can transform the polarization state of light," said Zhi Hao Jiang, a postdoctoral fellow in electrical engineering and lead author of a recent paper in Scientific Reports explaining their invention. "Polarization is one of the most fundamental properties of light. For instance, if we transform linearly polarized light into circularly polarized light, this could be useful in optical communication and biosensing."

Optical waveplates with broadband polarization conversion over a wide field of view are highly sought after. Conventional waveplates, made from multilayer stacks of materials such as quartz, have difficulty achieving both broadband and wide-angle conversion. Thin waveplates have been demonstrated, but their efficiency was low, with an average power efficiency of less than 50%. The team's nanofabricated waveplates achieved measured polarization conversion rates higher than 92% over more than an octave bandwidth with a wide field-of-view of around 40 degrees.

"In this paper, we demonstrated with simulation and experiment both quarter-waveplate and half-waveplate metasurfaces, which are thin artificial surfaces that operate both in the visible spectrum as well as in the near infrared," said Jeremy Bossard, a postdoctoral researcher who is a member of the team but not an author on the paper. "It also has a wide field of view, which means that if you illuminate the surface from a wide range of angles, it would still give the same reflective performance."

As a component in an optical setup, the nanostructured waveplate offers a thinner form factor and reduced weight for space applications, a wider field of view, which can reduce the number of optical components in a system, and can achieve very wide broadband functionality in the visible to near infrared wavelength range. This represents a new state-of-the-art for optical metasurface-based devices and will enable other types of ultrathin highly efficient optical components, the authors said.

Source: Penn State Univ.

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二维超材料表面操纵光

在左侧，圆偏振光可以在基于超材料的四分之一波长晶片的反射中，转换成线性偏振波。在右侧是制造出的纳米结构的场发射扫描电镜的俯视图，显示出了纳米线阵列。图片提供：宾州州立大学.

宾州州立大学电器工程师研究小组已经设计、制造并检测了金属纳米结构的单层，使研究小组可以提供操纵光的能力。工程化的表面结构由强耦合的纳米谐振器的周期阵列组成，可以提高科研设备、传感或卫星传输中执行光学特性系统的性能。

Zhi Hao Jiang是电子工程系的博士后，也是最近发布在《科学报告》上说明此项发明的论文的第一作者，他说：“我们设计并制造出了一种波晶片，这种波晶片可以传输光的偏振状态。偏振是光最基本的属性之一。例如，如果我们把线性偏振光转换成圆偏振光，那么这种波晶片在光通信和生物传感中就十分有用。”

有宽带偏振转换，并且具有广视域的光学波片是十分受欢迎的。传统的光学波片，是由向石英等材料的多层堆叠制成，很难同时达到广视域和广角转换。薄的光学波片已经显示出来了，但是效率很低，平均功率效率小于 50%。研究小组用纳米技术制造的波片测出的偏振转化率，要比 40°宽视场的倍频程带宽高出 92%。

博士后研究人员 Jeremy Bossard，是研究小组中的一员，但并未参与论文撰写。他说：“在本研究论文中，我们通过模拟和试验展示了四分之一波片和二分之一波片的超材料表面，超材料表面是薄的人工表面，可以在可见光范围内以及近红外光范围内运行。“该表面有一系列不同的视场，也就是说如果从不同角度照亮表面，它仍显示相同的反射性能。”

作为光学架设的元件之一，纳米结构的波片可以提供更薄的形状参数，并且降低空间应用的重量，更宽的视场，可以降低系统中光学元件的数量，并且可以在可见光到近红外的波长范围内提供更宽的宽频功能。作者称，这代表了光学超表面设备的最先进技术，并且将让其他超薄类型成为更有效的光学元件。

来源：宾州州立大学。

Honeybee hive sealant promotes hair growth in mice

Hair loss can be devastating for the millions of men and women who experience it. Now scientists are reporting that a substance from honeybee hives might contain clues for developing a potential new therapy. They found that the material, called propolis, encouraged hair growth in mice. The study appears in the Journal of Agricultural and Food Chemistry.

Ken Kobayashi and colleagues note that propolis is a resin-like material that honeybees use to seal small gaps in their hives. Not only does it work as a physical barrier, but it also contains active compounds that fight fungal and bacterial invasions. People from ancient times had noticed propolis' special properties and used it to treat tumors,

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inflammation and wounds. More recently, research has shown that the substance promotes the growth of certain cells involved in hair growth though no one had yet tested whether that in turn would result in new locks. Kobayashi's team wanted to find out.

When the researchers tested propolis on mice that had been shaved or waxed, the mice that received the treatment regrew their fur faster than those that didn't. The scientists also noticed that after the topical application, the number of special cells involved in the process of growing hair increased. Although they tried the material on mice that could grow fur rather than balding mice, the researchers note that hair loss conditions often result from abnormal inflammation. Propolis contains anti-inflammatory compounds, so they expect it could help treat balding conditions. They add that further testing is needed to see if the beehive material affects human hair follicles.

Source: American Chemical Society

蜜蜂蜂巢密封胶可促进老鼠毛发生长严重脱发对人们来说影响很大，而科学家称，蜜蜂蜂巢中的一种物质可能会有助于研制解决该问题

的新疗法。他们发现，此种叫做蜂胶的物质可以促进老鼠毛发生长。此项研究发表在《农业及食品化学期刊》（Journal of Agricultural and Food Chemistry）。

肯恩•小林健（Ken Kobayashi）及其同事指出，蜂胶是一种树脂样物质，是蜜蜂用来密封其蜂巢间小空隙的。其不仅可以用作物理屏障，包含的活性成分还可抵制真菌和细菌入侵。古代时候，人们就已注意到蜂胶的独特属性，并用其治疗肿瘤、炎症和伤口。而近期研究表明这种物质可以促进毛发中某些细胞生长，尽管还未对其副作用进行验证。小林带领的团队相对此一探究竟。

研究员们对剃过毛发或打过蜡的老鼠进行蜂胶测试，结果显示接受蜂胶治疗的老鼠比没有接受的毛发生长快许多。他们还发现此项局部治疗之后，控制毛发生长相关细胞的数量有所增加。虽然研究员们证明蜂胶可以促进老鼠毛发生长，但是他们也指出脱发通常是由炎症引起的。由于蜂胶含有抗炎物质，因而他们预估其也可以治疗脱发。研究员们补充说道还需进一步测试证明此物质是否可促进人体毛发生长。

来源：美国化学学会

Metal Alloy（金属合金）Improved Powder Metallurgy superalloy developed at ONERA

ONERA, the French aerospace laboratory based in Chatillon, reported at the recent EuroSuperalloys 2014 conference held in Giens, France, that researchers have successfully optimised and upgraded the microstructure and mechanical properties of a patented nickel-base Powder Metallurgy (PM) superalloy designated N19. The composition of the PM superalloy is shown in Table 1. The enhanced mechanical properties which have been obtained confirms the alloy’s potential for aeroengine turbine disk applications.

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Table 1 Composition of N19 alloy in weight percent

Didier Locq and colleagues from ONERA, along with colleagues from MinesParisTech and SNECMA, reported in their paper ‘Metallurgical Optimization of PM Superalloy N19’ that they investigated different heat treatment regimes (Table 2) which were used to reach the best compromise between static strength and cyclic resistance for the N19 superalloy.

Table 2 Heat treatment conditions

The alloy was produced by Hot Isostatic Pressing (HIP) argon atomised powder (<53 micron) at 1160°C and 100 MPa for 3 hrs. The HIPed billets were then extruded at 1070°C with a 5.5 extrusion ratio and cut sections were isothermally forged into pancake shapes about 190 mm in diameter and 28 mm thick.

The researchers found whilst the grain size in PM superalloys is usually limited to 25 microns, a coarser grain microstructure obtained after solutioning heat treatment exhibited better creep and crack propagation resistance as well as a reduced propensity for crack nucleation from ceramic inclusions under fatigue loading. This was due to the distribution, sizes and morphologies of secondary and tertary y’ being significantly modified by the cooling path after solution heat treatment.

The route enabling grain coarsening up to 50-70 micron for the N19 superalloy is to be investigated in further research.

法国航空航天实验室研发出改良的粉末冶金高温合金ONERA是总部位于查狄伦的一家法国航空航天实验室，它在最近法国吉安举办的 2014年欧洲粉末

冶金会议上报道称，其研究人员已经成功地优化和升级了一种被称为 N19的用粉末冶金工艺制作的镍基超耐热不锈钢的微观结构和力学性能，并已申请专利。这种高温合金的组成如表 1所示。获得的增强机械9


性能证实了高合金在航空发动机涡轮盘上的应用前景。

表 1 N19合金的组成（重量百分数）Didier Locq及其在法国航空航天实验室的同事们，以及来自MinesParisTech和斯奈克玛公司的同事们，

在他们的论文“高温合金 N19的冶金优化（Metallurgical Optimization of PM Superalloy N19）”中报道称，他们调查了不同的热处理程序(表 2)，以求达到N19高温合金的静强度和循环阻力的最佳折衷点。

表 2 热处理条件这种合金是由热等静压(HIP)氩气雾化粉末(< 53微米)在 1160°C和 100 MPa的条件下持续 3小时制作

而成的。然后这种经热等静压处理的坯料在 1070°C条件下按挤压比 5.5进行挤压，而割下的部分之后再被等温锻造成扁平形状，直径大约 190毫米、厚度 28毫米。

研究人员发现，这种粉末冶金制作的超合金的晶粒尺寸通常限定在 25微米左右，解析热处理后获得的粗颗粒微观结构表现出更好的蠕变和裂纹扩展阻力，同时减少疲劳载荷下陶瓷夹杂物的裂纹倾向。这是由于分布、大小和形态的中等以及冷却路径显著改善的固溶热处理解决方案。

使这种N19高温合金晶粒粗化到 50 - 70微米左右的热处理路线还需进行进一步的研究。

Scottish steel market set for expansion

Following a successful first 18 months for Barrett's Tube Division in Scotland, the company has announced a major investment north of the border with the launch of Barrett Steel Scotland.

The new business, based in Bathgate, will promote general steels to an expanding Scottish market, serving small and large steel users in a wide range of industries, from blacksmiths to major construction companies and large fabricators.

The company has ambitious growth plans and aims to be the largest independent steel stockholder in Scotland within the next five years.

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苏格兰钢铁市场准备扩张随着巴雷特（Barrett）钢铁苏格兰公司的成立，巴雷特管道部门在苏格兰经历了首个 18个月的成功，

随后公司宣布了一项在北部边境的重大投资计划。这个总部设在巴斯盖特（Bathgate）的新的业务部门，将向不断扩大的苏格兰市场推出常规钢，在行

业广泛的范围内为小型和大型钢铁用户提供服务，客户从铁匠到主要建筑公司和大型制造商等。公司制定了雄心勃勃的增长计划，目标是在未来五年成为苏格兰最大的独立钢铁股东。

Composite Materials（复合材料）High-temp composite replaces titanium on Nasa’s Shuttle successor

TenCate Advanced Composites developed a heat resistant composite material that is being used to provide a heat shield and backshell structure of the Lockheed Martin Orion multi-purpose manned spacecraft, currently being tested and developed by Nasa.

The composite material has replaced what was initially earmarked to be a fully titanium structure, used to provide shielding to the space capsule during re-entry.

Lockheed Martin Space Systems thermal protection group worked closely with TenCate Advanced Composites to develop the special heat resistant composite resin for the 5m diameter heat shield that will protect crew during the capsules re-entry.

The successful launch and subsequent re-entry last month of Orion multi-purpose development vehicle saw the material validated.

Steve Mead, Vice President of marketing and sales at TenCate Advanced Composites said: "The flight represents the culmination of a five year development and qualification effort for a suite of materials used in this extreme application. Further, as a result of the heat shield's large size and thickness, the advanced composites used had to achieve high consolidation using only a low pressure vacuum bag only process."

The Orion spacecraft is a multi-stage to orbit rocket that will replace the now retired Shuttle. It is due for manned launch in 2018 and is hoped to allow a mission to Mars by 2025.

美国宇航局用高温复合代替钛先进复合材料公司（TenCate Advanced Composites）发明了一种耐热复合材料，用来作为隔热板，以

及 Lockheed Martin Orion多功能载人飞船的底壳结构，美国国家宇航局正在对其进行研发与试验。这一复合材料已经取代了最初的全钛结构，用来为重返太空的太空船提供保护。

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马丁太空系统公司（Lockheed Martin Space Systems）热保护组与先进复合材料公司密切合作，目的是发明耐热复合树脂，制造直径是 5米的隔热板，这一隔热板在重返太空时可以保护宇航员。

上个月， “猎户座”多功能运输机的成功发射和重返证明了这一材料的有效性。Steve Mead是先进复合材料公司营销部副经理，他说：“这次飞行代表了 5年来发展用于该极端环境

中的一套材料的高潮。而且，由于隔热板的大尺度和厚度，使用的先进材料不得不仅仅通过低压力太空袋而达到高度整合。

Orion太空船是多级入轨火箭，这一火箭会取代退化的太空船，这是因为 2018年的人工发射会使2025年到达火星的任务有望实现。

Composite wrap being used to repair metal pipes

A composite wrap is being used to repair metal pipework on site without the need of hot curing.

The SuperWrap II, by Harrogate based Belzona, has been optimised for use on a variety of difficult geometries including bends, straights and tees, tank walls and can also be used as a patch repair on larger diameter pipes. The resulting repair is expected to last in excess of 15 years.

The material used is a bespoke hybrid fabric combining glass and carbon fibres. Glass fibres give the sheet flexibility and act as a wet out indicator, while carbon fibres provide the strength needed to withstand the high pressures and mechanical loading.

It uses a cold curing fluid grade epoxy resin available for both cool ambient temperatures (from 5°C up to 60°C) and warmer ambient temperatures (20°C up to 80°C). Interestingly, the SuperWrap II has been designed to have a similar thermal expansion coefficient to steel, meaning both substrates will expand and contract at a similar rate, avoiding stress and fatigue building up between the substrantes.

The SuperWrap II also overcomes a common problem encountered by engineers when repairing pipework – the pressure within the pipe acting on the defect area causing the repair material to bend or bulge. However, by having a high Young's modulus of approximately 38000 MPa, the material retains an extremely high level of stiffness and resistance to bending forces.

用来修补金属管道的复合材料包装现在，我们可以用一种复合材料包装来对金属管道进行现场修复，且这一过程不需要热固化。由哈罗盖特镇的贝尔佐纳开发的超级包装二代（SuperWrap II）已被优化，可用于各种维修困难的几

何管道，这包括弯曲管、直道和三通管、罐壁，它也可以用来对较大直径的管道进行小块修补。维修效果预计将超过 15年。

所用的材料是一种结合玻璃纤维和碳纤维的定制混合织物。玻璃纤维使其具有灵活性，就像一个浸湿的指示剂，而碳纤维提供了承受高压力和机械载荷所需的强度。

它采用的是冷固化流体级环氧树脂，它在凉爽环境温度（5℃至 60℃）和温暖的环境温度（20℃至80℃）下都可以使用。有趣的是，SuperWrap II与钢具有类似的热膨胀系数，这意味着这两种基底将以类似的速率膨胀和收缩，从而避免了基底之间压力与疲劳的积累。

SuperWrap II还克服了工程师在修复管道时遇到的一个共同的问题——即，在管道内破损区域的压力12


会导致修复材料弯曲或隆起。然而，由于这种材料具有约 38000 MPa的高杨氏模量，所以它能保持相当高的刚度和耐弯曲力。

Practical Application（实际应用）Zinc-oxide materials tapped for tiny energy harvesting devices

This illustration shows stacked flexible nanogenerators (left), and a cross-sectional transmission electron microscopy image of the ZnO/AlN-stacked structure. The scale bar on the right represents 200 nm. Image: Giwan Yoon/Korea Advanced Institute of Science and Technology

Today, we're surrounded by a variety of electronic devices that are moving increasingly closer to us—we can attach and wear them, or even implant electronics inside our bodies.

Many types of smart devices are readily available and convenient to use. The goal now is to make wearable electronics that are flexible, sustainable and powered by ambient renewable energy.

This last goal inspired a group of Korea Advanced Institute of Science and Technology (KAIST) researchers to explore how the attractive physical features of zinc-oxide (ZnO) materials could be more effectively used to tap into abundant mechanical energy sources to power microdevices. They discovered that inserting aluminum nitride insulating layers into ZnO-based energy harvesting devices led to a significant improvement of the devices' performance. The researchers report their findings in Applied Physics Letters.

"Mechanical energy exists everywhere, all the time, and in a variety of forms—including movement, sound and vibration. The conversion from mechanical energy to electrical energy is a reliable approach to obtain electricity for powering the sustainable, wireless and flexible devices—free of environmental limitations," explained Giwan

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Yoon, a professor in the Dept. of Electrical Engineering at KAIST.

Piezoelectric materials such as ZnO, as well as several others, have the ability to convert mechanical energy to electrical energy, and vice versa. "ZnO nanostructures are particularly suitable as nanogenerator functional elements, thanks to their numerous virtues including transparency, lead-free biocompatibility, nanostructural formability, chemical stability and coupled piezoelectric and semiconductor properties," noted Yoon.

The key concept behind the group's work? Flexible ZnO-based micro energy harvesting devices, aka "nanogenerators," can essentially be comprised of piezoelectric ZnO nanorod or nanowire arrays sandwiched between two electrodes formed on the flexible substrates. In brief, the working mechanisms involved can be explained as a transient flow of electrons driven by the piezoelectric potential.

"When flexible devices can be easily mechanically deformed by various external excitations, strained ZnO nanorods or nanowires tend to generate polarized charges, which, in turn, generate piezoelectronic fields," said Yoon. "This allows charges to accumulate on electrodes and it generates an external current flow, which leads to electronic signals. Either we can use the electrical output signals directly or store them in energy storage devices."

Other researchers have reported that the use of insulating materials can help provide an extremely large potential barrier. "This makes it critically important that insulating materials are carefully selected and designed—taking both the material properties and the device operation mechanism into consideration," said Eunju Lee, a postdoctoral researcher in Yoon's group.

To date, however, there have been few efforts made to develop new insulating materials and assess their applicability to nanogenerator devices or determine their effects on the device output performance.

The KAIST researchers proposed, for the first time, new piezoelectric ZnO/aluminum nitride (AlN) stacked layers for use in nanogenerators.

"We discovered that inserting AlN insulating layers into ZnO-based harvesting devices led to a significant improvement of their performance—regardless of the layer thickness and/or layer position in the devices," said Lee. "Also, the output voltage performance and polarity seem to depend on the relative position and thickness of the stacked ZnO and AlN layers, but this needs to be explored further."

The group's findings are expected to provide an effective approach for realizing highly energy-efficient ZnO-based micro energy harvesting devices. "This is particularly useful for self-powered electronic systems that require both ubiquity and sustainability—portable communication devices, health care monitoring devices, environmental monitoring devices and implantable medical devices," pointed out Yoon. And there are potentially many other applications.

Next up, Yoon and colleagues plan to pursue a more in-depth study to gain a much more precise and comprehensive understanding of device operation mechanisms. "We'll also explore the optimum device configurations and dimensions based on the operation mechanism analysis work," he added.

Source: American Institute of Physics

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为小型能量收集装置开发的氧化锌材料

这个图解显示了堆积的柔韧的纳米发电机（左边）和 ZnO/AlN堆积结构的横截面投射电子显微镜图像。右边的比例尺代表了 200 nm。图像提供：Giwan Yoon/Korea 科技高级研究所

今天，我们周围充斥着各种电子设备，而这些设备在逐渐向我们（的身体）靠近——我们现在已经可以穿戴这些设备，或甚至将电子产品移植在我们体内。

现在我们已经可以买到许多种智能设备，而且使用方便，现在的目标就是制造可穿戴的电子产品，且这些产品要具有可塑性、可持续性，并靠外界的可再生能源来驱动。

最后的这一目标激发了朝鲜科技高级研究所的一个组，来探索吸引人的氧化锌材料的物理特征是如何更有效地开发充足的机械能源从而发动微型设备的。他们发现，把氧化铝隔热层插入基于氧化锌的能源收集设备中，会使设备性能得到重大提高，研究人员的研究结果刊载于《应用物理学快报》（Applied Physics Letters）。

“机械能随时随地可见，以各种形式而存在——包括运动、声音和振动。从机械能到电能的转化是取得电力的可靠途径，可以用来发动可持续性、无线和柔性设备——不受坏境的限制，”朝鲜科技高级研究所电子工程系的教授Giwan Yoon说。

氧化铝灯压电材料就有能力将机械能源转化为电能。“氧化铝纳米结构作为纳米发电机功能元素尤为合适，因为其具备多种优良特性，包括透明性、无铅生物相容性、纳米结构成型性、化学稳定性、耦合压电和半导体性质，”Yoon说。

这一研究小组的关键研究理念是什么呢？柔性氧化锌微型能源收集设备，aka 纳米发电机，从本质上来说，是由压电氧化锌纳米棒或形成在柔性衬底上两个电极间的纳米射线组成的。简而言之，涉及到的工作机制可以解释为压电潜能驱动下的瞬变流动电子。

“弹性装置可以在外部力量下轻易变形，拉紧的氧化铝纳米棒或纳米电缆容易产生极化电荷，而极化电荷反过来产生压电场，”Yoon说。“这就允许充电在电极上积累，并产生外部电流，导致电信号。我们既可以直接使用电子输出信号，也可以在能源存储设备中将它们储存。

其他研究人员报道，使用隔热材料可以产生巨大的潜在障碍。“这就使得仔细筛选和设计隔热材料变得非常重要---将材料特性和设备操作机制都考虑在内，”Yoon组的博士后研究人员 Eunju Lee说。

然而，到现在为止，几乎没有很多人试图开发新隔热材料、评估将其运用在纳米发电机设备上的实用性，或确定它们对设备输出性能的影响。

朝鲜科技高级研究所的研究人员首次提出了用于纳米发电机的新型压电氧化铝堆积层。15


“我们发现，将AIN隔热层插在氧化锌收集设备，会大大提高它们的性能——不论设备中的层厚度和位置，”Lee说。而且，输出电压性能和极性可能要取决于堆积的氧化锌和AIN层的相关位置和厚度，但这需要深度探讨。”

小组的发现有望实现高度节能氧化锌微型能源收集设置。“这对自我发动的电子系统尤为有用，这一系统同时需要普遍性和可持续性 ---便携式通讯设备、医疗监督设备、环境监督设备和移植性医疗设备，”Yoon指出。可能还有其他方面的用途。

下一步，Yoon和同事们计划进行一项更加深入的研究，目的是更加精确、全面地理解设备操控机制。“我们也要探索基于运行机制分析的最优设备配置及维度，”他补充道。

来源：美国物理学研究所

Atomic placement of elements counts for strong concrete

A calcium-silicate-hydrate (aka cement) tip hovers above a smooth tobermorite surface in a computer simulation by Rice Univ. scientists. The researchers studied how atomic-level forces in particulate systems interact when friction is applied. Their calculations show such materials can be improved for specific applications by controlling the materials' chemical binding properties. Image: Shahsavari Group

Even when building big, every atom matters, according to new research on particle-based materials at Rice Univ.

Rice researchers Rouzbeh Shahsavari and Saroosh Jalilvand have published a study showing what happens at the nanoscale when “structurally complex” materials like concrete—a random jumble of elements rather than an ordered crystal—rub against each other. The scratches they leave behind can say a lot about their characteristics.

The researchers are the first to run sophisticated calculations that show how atomic-level forces affect the mechanical properties of a complex particle-based material. Their techniques suggest new ways to fine-tune the chemistry of such materials to make them less prone to cracking and more suitable for specific applications.

The research appears in Applied Materials and Interfaces.

The study used calcium-silicate-hydrate (C-S-H), aka cement, as a model particulate system. Shahsavari became quite familiar with C-S-H while participating in construction of the first atomic-scale models of the material.

C-S-H is the glue that binds the small rocks, gravel and sand in concrete. Though it looks like a paste before hardening, it consists of discrete nanoscale particles. The van der Waals and Coulombic forces that influence the

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interactions between the C-S-H and the larger particles are the key to the material’s overall strength and fracture properties, said Shahsavari. He decided to take a close look at those and other nanoscale mechanisms.

“Classical studies of friction on materials have been around for centuries,” he said. “It is known that if you make a surface rough, friction is going to increase. That’s a common technique in industry to prevent sliding: Rough surfaces block each other.

“What we discovered is that, besides those common mechanical roughening techniques, modulation of surface chemistry, which is less intuitive, can significantly affect the friction and thus the mechanical properties of the particulate system.”

Shahsavari said it’s a misconception that the bulk amount of a single element—for example, calcium in C-S-H—directly controls the mechanical properties of a particulate system. “We found that what controls properties inside particles could be completely different from what controls their surface interactions,” he said. While more calcium content at the surface would improve friction and thus the strength of the assembly, lower calcium content would benefit the strength of individual particles.

“This may seem contradictory, but it suggests that to achieve optimum mechanical properties for a particle system, new synthetic and processing conditions must be devised to place the elements in the right places,” he said.

The researchers also found the contribution of natural van der Waals attraction between molecules to be far more significant than Coulombic (electrostatic) forces in C-S-H. That, too, was primarily due to calcium, Shahsavari said.

To test their theories, Shahsavari and Jalilvand built computer models of rough C-S-H and smooth tobermorite. They dragged a virtual tip of the former across the top of the latter, scratching the surface to see how hard they would have to push its atoms to displace them. Their scratch simulations allowed them to decode the key forces and mechanics involved as well as to predict the inherent fracture toughness of tobermorite, numbers borne out by others’ experiments.

Shahsavari said atomic-level analysis could help improve a broad range of non-crystalline materials, including ceramics, sands, powders, grains and colloids.

Source: Rice Univ.

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元素的分子位置对高强混凝土十分重要

（图为）美国莱斯大学的科学家在计算机上模拟出了水合硅酸钙（又名水泥）颗粒，其悬浮在平滑的雪硅钙石表面。研究人员研究了在运用摩擦力时粒子系统中分子级别作用力是如何相互作用的。研究人员的计算表明，通过控制物质的结合特性，材料的在特定方面的应用特性就可以提高。

根据美国莱斯大学对粒子材料的新研究，尽管构建的分子较大，但每个原子都很重要。美国莱斯大学的研究人员 Rouzbeh Shahsavari和 Saroosh Jalilvand发表了一项研究，研究说明了当像

混凝土这样结构复杂的材料相互摩擦时在纳米层次上发生的具体情况；混凝土是元素的随机堆积，而非整齐的晶体。他们碰撞产生的划痕可以说明有关其特性的很多问题。

研究人员第一次进行复杂的计算，说明原子级的势能如何影响复杂粒子材料的力学特性。研究人员的技术显示出一种新的方法，今后可以通过调整这些材料的化学性质，让他们不宜破裂，且更加适合于特定的应用。

此研究结果刊载于《应用材料与界面》上（Applied Materials and Interfaces）。研究将水合硅酸钙（C-S-H），又名水泥，作为颗粒系统模型。Shahsavari十分熟悉 C-S-H，水泥参与

第一个原子模型的构建。C-S-H是结合混凝土中小石块、砾石和沙子的粘合剂。尽管C-S-H在变硬之前看起来像面团，但是 C-

S-H是由离散纳米颗粒构成的。Shahsavari说，范德华力和库仑力影响了 C-S-H和大分子的相互作用，范德华力和库仑力是材料总体强度和断裂性能的关键因素。Shahsavari决定观察这些和其他纳米级的机制。

Shahsavari说，材料摩擦力的经典研究已经持续了近几个世纪。大家都知道在粗糙的物体表面，摩擦力更大。这是工业中常用的方法技术：将粗糙的表面叠加在一起。

我们发现，除了常用的机械粗加工技术，不直观的表面化学性质的调节，会明显地影响摩擦力以及颗粒系统的力学特性。

Shahsavari说，大家有一种误解，认为单各元素的体积，例如 C-S-H的钙，控制颗粒系统的力学特性。他说：“我们发现，控制分子内部力学特性的物质，不同于控制表明作用力的物质”。尽管表面含有较多的钙可以增加摩擦力，从而增加凝聚力，但是较低的钙含量可以让个体粒子的强度增加。

Shahsavari说，这看起来有些矛盾，但是这表明，为了使粒子系统实现最优力学性能，必须要求设新的合成与处理条件，让元素处于正确的位置上。

Shahsavari说，研究人员还发现，在 C-S-H中，由于钙的作用，分子间自然的范德华吸引力的分布要比库伦力（静电式）明显。

为了检验他们的理论，Shahsavari 和 Jalilvand建立了粗糙的 C-S-H和光滑的水化硅酸钙的计算机模型。他们将前者的虚拟颗粒拖在后者的上面，进行摩擦表面，观察需要多大的力才能将原子错位。这些摩擦模

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拟允许他们解码关键的力和相关力学，并预测水化硅酸钙的固有摩擦力，数据由其他试验支持。Shahsavari说，原子级的分析可以有助于提高非晶体材料的范围，包括陶瓷、砂子、粉末、颗粒和胶体。来源：美国莱斯大学

Wearable sensor clears path to long-term EKG, EMG monitoring

Researchers from North Carolina State Univ. have developed a new, wearable sensor that uses silver nanowires to monitor electrophysiological signals, such as electrocardiography (EKG) or electromyography (EMG). The new sensor is as accurate as the “wet electrode” sensors used in hospitals, but can be used for long-term monitoring and is more accurate than existing sensors when a patient is moving.

Long-term monitoring of electrophysiological signals can be used to track patient health or assist in medical research, and may also be used in the development of new powered prosthetics that respond to a patient’s muscular signals.

Electrophysiological sensors used in hospitals, such as EKGs, use wet electrodes that rely on an electrolytic gel between the sensor and the patient’s skin to improve the sensor’s ability to pick up the body’s electrical signals. However, this technology poses problems for long-term monitoring, because the gel dries up—irritating the patient’s skin and making the sensor less accurate.

The new nanowire sensor is comparable to the wet sensors in terms of signal quality, but is a “dry” electrode—it doesn’t use a gel layer, so doesn’t pose the same problems that wet sensors do.

“People have developed other dry electrodes in the past few years, and some have demonstrated the potential to rival the wet electrodes, but our new electrode has better signal quality than most—if not all—of the existing dry electrodes. It is more accurate,” says Dr. Yong Zhu, an associate professor of mechanical and aerospace engineering at NC State and senior author of a paper describing the work. “In addition, our electrode is mechanically robust, because the nanowires are inlaid in the polymer.”

The sensors stem from Zhu’s earlier work to create highly conductive and elastic conductors made from silver nanowires, and consist of one layer of nanowires in a stretchable polymer.

The new sensor is also more accurate than existing technologies at monitoring electrophysiological signals when a patient is in motion.

“The silver nanowire sensors conform to a patient’s skin, creating close contact,” Zhu says. “And, because the nanowires are so flexible, the sensor maintains that close contact even when the patient moves. The nanowires are also highly conductive, which is key to the high signal quality.”

The new sensors are also compatible with standard EKG- and EMG-reading devices.

“I think these sensors are essentially ready for use,” Zhu says “The raw materials of the sensor are comparable in cost to existing wet sensors, but we are still exploring ways of improving the manufacturing process to reduce the overall cost.”

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An uncorrected proof of the paper was published online in RSC Advances.

Source: North Carolina State Univ.

新型可穿戴传感器可长期监测心电图和肌电图来自北卡罗来纳州立大学的研究人员已经开发出一种新型可穿戴传感器，使用银质纳米线来监测电

生理信号，比如心电图或肌电图。这种新型传感器与在医院使用的“湿电极”传感器一样精确，但其还可被用于长期监测，且在病人行动时比现有的传感器更精准。

长期监测的电生理信号可以被用来追踪病人的健康情况或者协助医学研究，也可以被用于开发新型可应答病人肌肉信号的动力假肢。

电生理传感器被用于医院，例如心电图，使用湿电极依靠的是传感器和病人皮肤之间的电解凝胶来改善传感器收集身体电信号的能力。然而，这项技术引出了长期监控技术方面的问题，因为凝胶干枯将刺激病人的皮肤，使传感器变得不准确。

新的纳米线传感器在信号质量方面堪比湿传感器，而它是一个“干”电极——它不使用凝胶层，因此不会造成与湿传感器同样的问题。

“人们已经在过去几年里开发出了其他干电极，而且其中一些被证明可与湿电极竞争，但我们的新电极比其中的大多数具备更好的信号质量——对于现有的干电极来说。它更加准确。”朱勇博士说，北卡罗莱纳州机械和航空航天工程教授和高级作者的一篇论文描述了这项工作。“此外，我们的电极具备物理坚韧性，因为纳米线被镶嵌在聚合物中”。

传感器源于朱早期通过银质纳米线创造出的高导电弹性导体，由可伸缩聚合物内的一层纳米线组成。新型传感器在监测病人运动状态下的电生理信号也比现有技术更准确。“该银质纳米线传感器贴合病人的皮肤，创造了密切的接触。”朱勇博士说。“因为纳米线是如此的灵

活，传感器即使在病人运动时仍可保持与肌肤的密切接触。纳米线也具备了高导电性，而这正是高信号质量的关键。”

新型传感器也兼容标准心电图和肌电图扫描设备。“我认为这些传感器本质上已经做好了被使用的准备。传感器的原材料在成本方面可与现有的湿传感

器相媲美，但我们仍在探索改进制造过程的方法以降低整体成本。”论文样稿发表在在线版的 RSC Advances期刊。来源：北卡州立大学。

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Crush those clinkers while they’re hot

A cutaway illustration of a clinker, a pellet manufactured in a kiln and then ground to make cement, shows a defect called a screw dislocation. Rice Univ. scientists studied the effect of such defects on the quality of cement used in concrete and how much energy could be saved by modifying the manufacturing process. Image: Shahsavari Group

Making cement is a centuries-old art that has yet to be perfected, according to researchers at Rice Univ. who believe it can be still more efficient.

Former Rice graduate student Lu Chen and materials scientist Rouzbeh Shahsavari calculated that fine-tuning the process by which round lumps of calcium silicate called clinkers are turned into cement can save a lot of energy. Their new findings are detailed in Applied Materials and Interfaces.

Manufacturers of Portland cement, the most common type in use around the world, make clinkers by heating raw elements in a rotary kiln and grinding them into the fine powder that becomes cement. Mixed with water, cement becomes the glue that holds concrete together. An earlier study by Shahsavari and his colleagues that viewed the molecular structure of cement noted that worldwide, concrete manufacturing is responsible for 5 to 10% of the carbon dioxide, a greenhouse gas, released into the atmosphere.

The researchers analyzed the crystal and atomic structures of five phases of clinkers representing stages of cooling after they leave the kiln. They focused on the internal stresses that make some more brittle (and easier to grind) than others. They also looked at the unavoidable defects called screw dislocations, shear offsets in the raw materials that, even when ground, influence how well the powders mix with water. That reactivity determines the cement’s ultimate strength.

They found that clinkers were not only most brittle when hottest, but also the most reactive. In ranking the five samples’ qualities, they suggested their research could lead manufacturers to consolidate processes and cut grinding energy that now absorbs around 10 to 12% of the energy required to make cement. Equally important, for each ton of produced cement, the grinding energy accounts for roughly 50 kg of carbon dioxide emissions into the atmosphere, they determined.

“Defects form naturally, and you cannot do anything about them,” Shahsavari said. “But the more brittle the

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clinkers are, the better they are for grinding. We found that the initial phase out of the kiln is the most brittle and that defects carry through to the powder. These are places where water molecules want to react.”

Source: Rice Univ.

在熟料高温时粉碎它们

熟料是在高炉中制造出的一种球团矿，可在研磨后用来制造水泥。以上为一张熟料的截面示意图，显示出了一个被称为螺旋位错的缺陷。莱斯大学科学家研究了此类缺陷对用于生产混凝土的水泥的质量的影响并研究了通过修改生产过程可以节省多少能量。图片提供：Shahsavari集团

制作水泥是一种还有待完善的古老艺术，根据赖斯大学的研究人员研究称，他们相信水泥可以进行更高效的生产。

前赖斯大学的研究生陈路（音）和材料科学家 Rouzbeh Shahsavari经计算得出，微调将圆形块状的硅酸钙熟料制成水泥的过程，可以节省大量能源。他们的新发现详细刊登在《应用材料和界面》（Applied Materials and Interfaces）杂志上。

波特兰水泥是世界各地最常见的使用的水泥类型，其制造商经回转窑加热生料来制作熟料，然后将其磨成细粉，制成水泥。再与水混合，水泥就会变成胶水一样的混凝土。Shahsavari和他的同事们早先研究水泥的分子结构时指出，在世界范围内，混凝土生产直接将 5%到 10%的二氧化碳温室气体排放到了大气中。

研究人员分析了水泥从熟料炉中取出后冷却的五个阶段的晶体和原子结构。他们专注于内部应力的研究，这些应力能造成更多裂纹（使颗粒更容易磨碎）。他们还注意到不可避免的称为螺旋位错缺陷，它们抵消掉原材料中剪切应力，即使研磨后，仍能影响粉末与水混合的好坏程度。这种反应性质决定了水泥的强度极限。

他们发现，熟料在最热的时候不仅最脆弱，也是最易反应的。对五个样品的品质进行排序后，他们认为，他们的研究可能会指导制造商整合生产过程并减少磨削能量的消耗，现在能吸收大约 10% - 12%的用于生产水泥的能量。同样重要的是，他们计算得出，每生产一顿水泥，研磨消耗的能量相当于将 50公斤的二氧化碳排放到大气中。

“对自然形成的缺陷，你无能为力，”Shahsavari说。“但对于熟料来说，它们越脆，磨得就越好。我们发现，从加热炉中取出后的最初始阶段熟料是最脆的，那些缺陷会一直存在，直到制成粉末。这些水分子有时候是很容易反应的。”

资料来源：赖斯大学。22


Organic & Polymer（有机高分子材料）Catalyst process uses light for rapid polymerization

A team of chemistry and materials science experts from Univ. of California, Santa Barbara and The Dow Chemical Company has created a novel way to overcome one of the major hurdles preventing the widespread use of controlled radical polymerization.

In a global polymer industry valued in the hundreds of billions, a technique called Atom Transfer Radical Polymerization is emerging as a key process for creating well-defined polymers for a vast range of materials, from adhesives to electronics. However, current ATRP methods by design use metal catalysts, a major roadblock to applications for which metal contamination is an issue, such as materials used for biomedical purposes.

This new method of radical polymerization doesn’t involve heavy metal catalysts like copper. Their innovative, metal-free ATRP process uses an organic-based photocatalyst—and light as the stimulus for the highly controlled chemical reaction.

“The grand challenge in ATRP has been: how can we do this without any metals?” said Craig Hawker, Director of the Dow Materials Institute at UC Santa Barbara. “We looked toward developing an organic catalyst that is highly reducing in the excited state, and we found it in an easily prepared catalyst, phenothiazine.”

“It’s “drop-in” technology for industry,” said Javier Read de Alaniz, principal investigator and professor of chemistry and biochemistry at UC Santa Barbara. “People are already used to the same starting materials for ATRP, but now we have the ability to do it without copper.” Copper, even at trace levels, is a problem for microelectronics because it acts as a conductor, and for biological applications because of its toxicity to organisms and cells.

Read de Alaniz, Hawker and postdoctoral researcher Brett Fors, now with Cornell Univ., led the study that was initially inspired by a photoreactive Iridium catalyst. Their study is published in the Journal of the American Chemical Society.

ATRP is already used widely across dozens of major industries, but the new metal-free rapid polymerization process “pushes controlled radical polymerization into new areas and new applications,” according to Hawker. “Many processes in use today all start with ATRP. Now this method opens doors for a new class of organic-based photoredox catalysts.”

Controlling radical polymerization processes is critical for the synthesis of functional block polymers. As a catalyst, phenothiazine builds block copolymers in a sequential manner, achieving high chain-end fidelity. This translates into a high degree of versatility in polymer structure, as well as an efficient process.

“Our process doesn’t need heat. You can do this at room temperature with simple LED lights,” said Hawker. “We’ve had success with a range of vinyl monomers, so this polymerization strategy is useful on many levels.”

“The development of living radical processes, such as ATRP, is arguably one of the biggest things to happen in

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polymer chemistry in the past few decades,” he added. “This new discovery will significantly further the whole field.”

Source: Univ. of California, Santa Barbara

用光催化过程实现快速聚合来自美国加州大学圣芭芭拉分校和陶氏化学公司的化学材料科学专家们创造了一种新的工艺方法，

可以克服阻止可控自由基聚合广泛使用的一个主要障碍。全球聚合物的产业价值多达数千亿美元，原子转移自由基聚合（以下简称 ATRP）技术的出现对制造

明确聚合物是非常关键的工艺，这些聚合物应用十分广泛，从胶黏剂到电子都有涉及。然而，当前的ATRP方法使用的是金属催化剂，其应用的一个主要障碍是金属污染问题，例如用于生物医学用途的材料。

这种自由基聚合的新方法不涉及铜类重金属催化剂。它们的创新之处在于，无金属 ATRP的工艺使用了一种有机的光催化剂，而且光作为高度可控化学反应的刺激物。

加州大学圣芭芭拉分校DOW材料研究所主任 CraingHawker说：“ATRP的巨大挑战是：我们要如何才能做到这一点且不产生任何的金属污染？我们希望望研发一种有机催化剂，它能够高度地降低激发状态，而且我们发现吩噻嗪是一种比较容易制成的催化剂。”

“这是工业的‘嵌入式’技术”，加州大学圣芭芭拉分校化学和生物化学首席研究员 Javier Read de Alaniz教授说。“人们已经习惯对 ATRP使用相同的原材料，但现在我们必须在没有铜的情况下做到这一点。”即使痕量水平的铜也因其作为导体的特性以及对生物体和细胞的毒性，而分别在微电子和生物学应用方面存在问题。

Read de Alaniz、Hawker和 Brett Fors 博士后，现已与美国康奈尔大学一起主导这项研究，其最初由光敏铱催化剂受到启发，他们的研究最近已发表在《美国化学学会会刊》（ the Journal of the American Chemical Society）上。

ATRP已经广泛应用于数十个主要行业，但新的无金属快速聚合工艺可“推动可控自由基聚合进入新领域和新应用”，据Hawker说。“目前使用的许多工艺开始于ATRP，现在这个方法为新一类的有机光还原催化剂打开了大门。”

可控自由基聚合工艺对于合成功能嵌段聚合物来说是至关重要的。作为催化剂，吩噻嗪以顺序的方式构建了嵌段共聚物，实现高度的首尾相连。这转化为聚合物结构的高度通用性以及一种有效的工艺方法。

“我们的过程并不需要热量，你可以在室温下用简单的 LED灯就能做到，”Hawker说。“我们已经成功地获得一系列的乙烯基单体，所以这个聚合策略在很多层面上都是非常有用的。”

“活性自由基工艺，如 ATRP的发展，可以说是过去几十年中发生在高分子化学的最大事情之一”，他补充说，“这一新发现将显著推进整个领域的发展。”

来源：加州大学圣芭芭拉分校

Solar cell polymers with multiplied electrical output

One challenge in improving the efficiency of solar cells is that some of the absorbed light energy is lost as heat. So scientists have been looking to design materials that can convert more of that energy into useful electricity. Now a team from the U.S. Dept. of Energy (DOE)'s Brookhaven National Laboratory and Columbia Univ. has paired up polymers that recover some of that lost energy by producing two electrical charge carriers per unit of light instead

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of the usual one.

"Critically, we show how this multiplication process can be made efficient on a single molecular polymer chain," said physicist Matthew Sfeir, who led the research at Brookhaven Lab's Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility. Having the two charges on the same molecule means the light-absorbing, energy-producing materials don't have to be arrayed as perfect crystals to produce extra electrical charges. Instead, the self-contained materials work efficiently when dissolved in liquids, which opens the way for a wide range of industrial scale manufacturing processes, including "printing" solar-energy-producing material like ink.

The research is published in Nature Materials.

The concept of producing two charges from one unit of light is called "singlet fission." (Think of the fission that splits a single biological cell into two when cells multiply.) Devices based on this multiplication concept have the potential to break through the upper limit on the efficiency of so-called single junction solar cells, which is currently around 34%. The challenges go beyond doubling the electrical output of the solar cell materials, because these materials must be incorporated into actual current-producing devices. But the hope is that the more-efficient current-generating materials could be added on to existing solar cell materials and device structures, or spark new types of solar cell designs.

Most singlet fission materials explored so far result in twin charge carriers being produced on separate molecules. These only work well when the material is in a crystalline film with long-range order, where strong coupling results in an additional charge being produced on a neighboring molecule. Producing such high quality crystalline films and integrating them with solar cell manufacturing complicates the process.

Producing the twin charges on a single polymer molecule, in contrast, results in a material that's compatible with a much wider variety of industrial processes.

The materials were designed and synthesized by a Columbia Univ. team led by Professor Luis Campos, and analyzed at Brookhaven using specialized tools at the CFN and in the Chemistry Dept. For Sfeir and Campos, the most fascinating part of the interdisciplinary project was exploring the electronic and chemical requirements that enable this multiplication process to occur efficiently.

"We expect a significant leap in the development of third-generation, hot-carrier solar cells," said Campos. "This approach is especially promising because the materials' design is modular and amenable to current synthetic strategies that are being explored in second-generation organic solar cells."

Details of the materials' analysis

At the CFN, Sfeir and Erik Busby (a postdoctoral fellow) used time-resolved optical spectroscopy to induce and quantify singlet fission in the various polymer compositions using a single laser photon. Xiaoyang Zhu of Columbia helped to understand the data and interpret results.

"We put light energy into a material with a laser pulse and watch what happens to that energy using a series of weaker light pulses—somewhat analogous to taking snapshots using a camera with a very fast shutter," Sfeir said.

The team also studied the same process using "pulse radiolysis" in collaboration with John Miller, who runs the Laser-Electron Accelerator Facility.

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"The differences observed between these two experiments allowed us to unambiguously identify singlet fission as the primary process responsible for the production of these twin charges," Sfeir said.

With Qin Wu, the team also used a powerful computer cluster at the CFN to model these materials and understand the design requirements that were necessary for singlet fission to take place.

"The ideas for this project and supervision of the work were really shared between Brookhaven and Columbia," Sfeir said. "It's a great example of the kind of collaborative work that takes place at DOE user facilities like the CFN."

The next steps for the CFN-Columbia team will be to test a large class of materials using the design framework they've identified, and then integrate some of these carbon-based polymer materials into functioning solar cells.

"Even though we have demonstrated the concept of multiplication in single molecules," Sfeir said, "the next challenge is to show we can harness the extra excitations in an operating device. This may be in conventional bulk type solar cells, or in third-generation concepts based on other inorganic (non-carbon) nanomaterials. The dream is to build hot-carrier solar cells that could be fully assembled using solution processing of our organic singlet fission materials."

Source: Brookhaven National Laboratory

新型太阳能电池聚合物增加电量输出提高太阳能电池效率的一个挑战，就是一些吸收的光能会以热的形式丢失，所以科学家正在设计一

些可以把更多能量转化为有用电能的材料。现在美国能源部门的一个组已经将聚合物进行了配对，这些聚合物通过在每一个光单位上产生两个电荷从而恢复一些丢失的能源。

“最重要的是，我们展示了这个增加过程是如何在单个分子聚合物链上产生效果的，”物理学家Matthew Sfeir说，他领导了功能纳米材料中心的研究。同一个分子上有两个电荷，这就意味着吸收光、产生能源的材料不必排列为产生额外电荷的完美晶体；相反，这种独立的材料能在溶解为液体时有效工作这就为大范围的工业规模生产流程打开了道路，包括像墨一样“打印”太阳能材料。

研究结果刊载于《自然材料》（Nature Materials）杂志上。在一个光单位上产生两个电荷这一概念被称为“单个裂变”（正如将一个生物细胞分裂为两个这样

的裂变）。建立在这一增加概念上的设备可能会打破所谓的单洁太阳能电池的效率上限，而现在是 34%。挑战不仅仅是使太阳能电池材料的电产量翻倍，因为这些材料必须与目前实际生产设备相结合，但是有希望将现在更有效的材料加在太阳能电池材料和设备结构上，或者是激发新的太阳能电池设计种类。

目前探索到的大多数单线态裂变材料，可使在同的分子上产生两个电荷。只有当材料呈现为结晶薄膜时，才能很好地工作，这时额外电荷上的高耦合效果在附近的分子上产生。产生这样的高质量晶体薄膜，并将它们与太阳能电池的生产相结合，这就使过程变得复杂。

相反，在单个聚合物分子上产生双电荷就可以产生一种与更大范围的产业过程相容的材料。材料的设计与合成是由哥伦比亚大学的一个小组进行的，由 Luis Campos教授领导，并在 Brookhaven

运用食品与营养委员会的特殊工具进行了分析。对 For Sfeir和 Campos而言，这一跨学科项目中最有趣的部分，就是可以使这一倍增过程有效发生的电子与化学要求。

“我们希望在第三代热载流子太阳能电池研发方面取得重大进步，”Campos说。“这一方面很有前景，因为材料的设计是模块化的，且与现在的合成策略相匹配，而现有策略在第二代有机太阳能电池上进行

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了探索。”材料分析细节在食品与营养中心，Sfeir 和 Erik Busby（博士后）运用了时间分辨光谱学，来通过单束激光光子，

诱导和量化聚合物复合材料上的单线态分裂。哥伦比亚大学的朱晓阳（音译）参与了数据及结果解释。“我们用激光脉冲将光能放置在材料中，看看运用弱激光脉冲的能源会发生什么——就像运用快门照

相机进行速拍一样，”Sfeir 说。研究小组与 John Miller合作运用“脉冲辐解”研究了同一过程。而 John Miller经营着激光电子加速器

设备。“两个实验的不同允许我们明确将单线态裂变看做基本过程，这一过程与产生这些双电荷有

关，”Sfeir说。这个小组与武秦（音）在食品与营养中心运用强大的计算机集群制作了材料模型，理解了单线态裂

变发生所需的设计需求。“这一项目的理念与监管工作在 Brookhaven 和 Columbia之间进行了共享，”Sfeir 说。“这是合作工

作的典范。” CFN-Columbia 团队的下一步工作，就是运用他们识别的设计框架，对不同级别的材料进行测试，然

后将一些碳基聚合物材料结合为功能性太阳能电池。“即使我们在单个分子中阐明了增倍的概念，”Sfeir 说，“下一个挑战就是表明我们可以在操作设备

中利用这一额外的刺激。这可能发生在传统的大块太阳能电池上，或在以无机纳米材料为基础的第三代概念上。（我们的）梦想是建立热载流子的太阳能电池，使其可以用有机单线态裂变材料方法进行组装。”

来源：布鲁克黑文国家实验室

Solvay's New Xydar LCP Resin Meets Demands of High-Speed Surface Mount Connectors

Solvay Specialty Polymers has introduced Xydar MG-850 liquid crystal polymer (LCP), a new specially designed grade that meets the rigorous performance and processing demands of new high-speed USB 3.0 surface mount connectors.

This new material is designed to deliver the high flow, flatness, and dimensional stability required for new 12-gigabyte connectors that target applications in desktop and laptop computers, as well as tablets.

"The connector industry's adoption of advanced fine-pitch technology* has placed even more exacting demands on materials," said Glenn Cupta, Global Business Development Manager for electrical/electronics at Solvay. "Xydar MG-850 LCP offers manufacturers exceptional performance for these next-generation connectors, providing even tighter tolerances and lower warpage compared to our standard LCP material."

According to Solvay, Xydar MG-850 LCP is a 50 percent glass/mineral reinforced polymer that fills thin walls over long flow lengths. The proprietary mineral and glass reinforcement package provides excellent warp resistance. It also exhibits a heat deflection temperature of 271°C (520°F) and infrared reflow capability up to 260°C (500°F). The material's low moisture absorption facilitates improved IR reflow performance, according to Cupta.

Solvay says its new injection mouldable grade offers performance advantages over competitive low-warp LCPs,

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and doesn't suffer from corrosion issues exhibited by other rival material technologies, such as halogen-free flame retardant polyphthalamide (PPA) resins. It explains that Xydar LCP is inherently flame retardant, transparent to microwave radiation and resistant to virtually all chemicals. The material has an UL 94 V0 flammability rating from Underwriters Laboratories of 0.2 mm without additives.

Available in black or natural colours, Xydar MG-850 LCP is sold globally to leading processors and connector manufacturers, with whom Solvay is working closely to help facilitate its application in next-generation USB 3.0 surface mount connectors for the personal computing market.

索尔维集团的新型 Xydar LCP 树脂材料可用于高速表面安装连接器

索尔维集团（Solvay Specialty Polymers）推出了 Xydar MG-850液晶聚合物（LCP），这是一种新的特殊设计级别的聚合物，满足新型高速USB 3.0安装连接器严格的性能和表面处理要求。

这种新材料旨在为新型 12-吉字节的连接器提供高流量、平面度和尺寸稳定性，而连接器的应用目标为台式机和笔记本电脑，还有平板电脑。

索尔维集团电气/电子全球业务发展经理 Glenn Cupta表示，“连接器行业采用的先进的小模数的技术*对材料的要求更加严格”；“Xydar MG-850 LCP为这些新一代连接器制造商提供特殊性能，相比我们的标准 LCP材料，提供更严格的公差和更低的翘曲度。”

根据索尔维集团的介绍，Xydar MG-850 LCP是一个用来填充薄墙长流长度的 50%的玻璃/矿物增强聚合物。专有的矿物和玻璃钢筋包装显示出了出色的变形阻力。也显示了高达 271°C (520°F)的热挠曲温度，和高达 260°C (500°F)的红外回流能力。根据Cupta表示，该材料的低水分吸收能力促进改善红外回流性能。

索尔维集团表示，它的新的注射可塑级别为具有竞争力的低弯曲度 LCP提供性能优势，并且它不受腐蚀问题困扰，区别于其他竞争对手材料技术，如无卤阻燃聚邻苯二甲酰胺(PPA)树脂。它解释说，Xydar LCP是天生的阻燃剂，可以穿透微波辐射，并且抵抗几乎所有的化学物质。材料具备美国保险商实验室认证的 0.2毫米无添加剂UL 94 V0级别可燃性。

Xydar MG-850 LCP有黑色或自然颜色两种颜色，销售给全球范围内领先的处理器厂商和连接器制造商；而索尔维集团正在与这些商家紧密合作，帮助推进其在个人电脑市场的下一代 USB 3.0表面安装连接器上应用。

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Solving an organic semiconductor mystery

Sketch of organic semiconductor thin film shows that the interfacial region between larger domains (blue and green) consists of randomly oriented small, nanocrystalline domains (purple).

Organic semiconductors are prized for light-emitting diodes (LEDs), field effect transistors (FETs) and photovoltaic cells. As they can be printed from solution, they provide a highly scalable, cost-effective alternative to silicon-based devices. Uneven performances, however, have been a persistent problem. Scientists have known that the performance issues originate in the domain interfaces within organic semiconductor thin films, but have not known the cause. This mystery now appears to have been solved.

Naomi Ginsberg, a faculty chemist with the U.S. Dept. of Energy (DOE)’s Lawrence Berkeley National Laboratory and the Univ. of California (UC) Berkeley, led a team that used a unique form of microscopy to study the domain interfaces within an especially high-performing solution-processed organic semiconductor called TIPS-pentacene. She and her team discovered a cluttered jumble of randomly oriented nanocrystallites that become kinetically trapped in the interfaces during solution casting. Like debris on a highway, these nanocrystallites impede the flow of charge-carriers.

“If the interfaces were neat and clean, they wouldn’t have such a large impact on performance, but the presence of the nanocrystallites reduces charge-carrier mobility,” Ginsberg says. “Our nanocrystallite model for the interface, which is consistent with observations, provides critical information that can be used to correlate solution-processing methods to optimal device performances.”

Ginsberg, who holds appointments with Berkeley Lab’s Physical Biosciences Div. and its Materials Sciences Div., as well as UC Berkeley’s Depts. of Chemistry and Physics, is the corresponding author of a paper describing this research in Nature Communications.

Organic semiconductors are based on the ability of carbon to form larger molecules, such as benzene and pentacene, featuring electrical conductivity that falls somewhere between insulators and metals. Through solution-processing, organic materials can usually be fashioned into crystalline films without the expensive high-temperature annealing process required for silicon and other inorganic semiconductors. However, even though it has long been clear that the crystalline domain interfaces within semiconductor organic thin films are critical to their performance in devices, detailed information on the morphology of these interfaces has been missing until now.

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“Interface domains in organic semiconductor thin films are smaller than the diffraction limit, hidden from surface probe techniques such as atomic force microscopy, and their nanoscale heterogeneity is not typically resolved using x-ray methods,” Ginsberg says. “Furthermore, the crystalline TIPS-pentacene we studied has virtually zero emission, which means it can’t be studied with photoluminescence microscopy.”

Ginsberg and her group overcame the challenges by using transient absorption (TA) microscopy, a technique in which femtosecond laser pulses excite transient energy states and detectors measure the changes in the absorption spectra. The Berkeley researchers carried out TA microscopy on an optical microscope they constructed themselves that enabled them to generate focal volumes that are a thousand times smaller than is typical for conventional TA microscopes. They also deployed multiple different light polarizations that allowed them to isolate interface signals not seen in either of the adjacent domains.

“Instrumentation, including very good detectors, the painstaking collection of data to ensure good signal-to-noise ratios, and the way we crafted the experiment and analysis were all critical to our success,” Ginsberg says. “Our spatial resolution and light polarization sensitivity were also essential to be able to unequivocally see a signature of the interface that was not swamped by the bulk, which contributes much more to the raw signal by volume.”

The methology developed by Ginsberg and her team to uncover structural motifs at hidden interfaces in organic semiconductor thin films should add a predictive factor to scalable and affordable solution-processing of these materials. This predictive capability should help minimize discontinuities and maximize charge-carrier mobility. Currently, researchers use what is essentially a trial-and-error approach, in which different solution casting conditions are tested to see how well the resulting devices perform.

“Our methodology provides an important intermediary in the feedback loop of device optimization by characterizing the microscopic details of the films that go into the devices, and by inferring how the solution casting could have created the structures at the interfaces,” Ginsberg says. “As a result, we can suggest how to alter the delicate balance of solution casting parameters to make more functional films.”

Source: Lawrence Berkeley National Laboratory

解开有机半导体性能之谜

有机半导体薄膜图示显示出较大结构域（蓝色和绿色）之间的钎缝界面区由杂乱分布的小型纳米晶体结构域组成（紫色）。

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据科学日报报道，有机半导体对发光二极管（LED）、场效应晶体管（FETs）和光伏电池而言非常重要。由于它们可以通过溶液打印，所以它们具高度可伸缩性且成本效益较高，可作为硅设备的替代品。然而，性能表现参差不齐一直是有机半导体存在的一个问题。科学家们知道，性能问题源于有机半导体薄膜结构域界面，但却一直不清楚背后的原因，这一谜题直到近期才被解开。

美国能源部（DOE）劳伦斯伯克利国家实验室的科学家、美国加州大学伯克利分校的娜奥美•金斯伯格（Naomi Ginsberg）带领了一支科研小组，利用显微镜学的一种独特形式研究了名为 TIPS-pentacene的特殊高性能有机半导体的结构域界面。她和她的研究小组发现了一种混杂的随机排列的纳米微晶，在溶液浇铸时会被困于界面处。就像高速公路上的残骸一样，这些纳米微晶会阻碍电荷载流子的流动。

“如果界面干净整齐，它们就不会对性能产生巨大的影响，但纳米微晶的存在减少了电荷载流子的移动性，” 金斯伯格说道。“我们针对这个界面建立的纳米微晶模型——它与观测结果相一致——提供了至关重要的信息，它或可以被用于将处理溶剂的方法与最优的设备性能相联系。”

劳伦斯伯克利国家实验室物理生物部门和材料科学部门、美国加州大学伯克利分校化学和物理学学院的金斯伯格是这篇发表在《自然通信》期刊上的研究文论的通讯作者。

有机半导体基于碳的能力形成更大分子，例如苯环和并五苯，它们具有介于绝缘体和金属之间的导电性。通过溶液处理，有机材料可以无需昂贵的高温热处理——这些是硅和其它非有机半导体所必须经过的过程——就被塑造成晶体薄膜。然而，即使众所周知半导体有机薄膜里的晶体界面对于设备的性能表现至关重要，在这项研究之前有关这些界面的形态学信息仍是未知数。

“半导体薄膜界面比衍射极限还要小，表面探测技术，例如原子力显微镜都无法检测到它，此外利用X射线的方法一般无法解决它的纳米异质性，” 金斯伯格解释道。“此外，我们研究的晶体 TIPS-pentacene几乎为 0释放，这意味着利用光致发光显微镜也无法对其进行研究。”

金斯伯格和她的研究小组通过借助瞬态吸收光谱(TA)显微镜学克服了这一难题，这一技术是指利用飞秒激光脉冲激活瞬态能量状态，使得探测器可以测量吸收光谱的改变。研究小组在他们自己搭建的光学显微镜上进行了瞬态吸收光谱显微镜学，这使得他们可以产生比传统 TA显微镜学还要小一千倍的聚焦体积。他们还部署了不同的光偏振使得它们可以隔离临近区域无法观测到的界面信号。

“仪器设备，包括非常好的探测器，结合孜孜不倦的数据收集保证了较好的信噪比，而我们改变实验和分析的方法对于获得的成功至关重要，” 金斯伯格解释道，“我们的空间分辨率和光偏振敏感性对于明确观测到界面信号也非常重要。”

金斯伯格和她的研究小组提出的揭开有机半导体薄膜隐藏界面里结构图案的方法，将成为可伸缩、可负担的这些材料的新预测因素。这一预测能力将帮助减少不连续性并最大化电荷载流子移动性。目前研究人员采用的是反复试验法，通过对不同的溶液浇铸环境进行测试从而调查产生的设备的性能。

“我们的方法提供了设备最优化反馈回路里的重要媒介物，主要是通过定义进入设备的薄膜的微观细节，同时推断溶液浇铸将在界面处产生什么样的结构来实现的，” 金斯伯格这样表示，“结果是我们知道如何改变溶液浇铸参数之间的微妙平衡，从而产生更具功能性的薄膜。”

来源：劳伦斯伯克利国家实验室

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E-Material（电子材料）Researchers develop multiferroic materials, devices integrated with silicon chips

A research team led by North Carolina State Univ. has made two advances in multiferroic materials, including the ability to integrate them on a silicon chip, which will allow the development of new electronic memory devices. The researchers have already created prototypes of the devices and are in the process of testing them.

Multiferroic materials have both ferroelectric and ferromagnetic properties.

“These multiferroic materials offer the possibility of switching a material’s magnetism with an electric field, or switching its electric polarity with a magnetic field—making them very attractive for use in next-generation, low-power, nonvolatile memory storage devices,” says Dr. Jay Narayan, John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State and senior author of two papers describing the work.

Researchers had previously known that you could create a multiferroic material by layering barium titanate (BTO), which is ferroelectric, and lanthanum strontium magnese oxide (LSMO), which is ferromagnetic. But these “bilayer” thin films weren’t feasible for large-scale use because they could not be integrated on a silicon chip – the constituent elements of the thin films would diffuse into the silicon.

But Narayan’s team has advanced the work in two ways. First, by developing a technique to give BTO ferromagnetic properties, making it multiferroic without the need for LSMO; second, by developing buffer layers that can be used to integrate either the multiferroic BTO or the multiferroic BTO/LSMO bilayer film onto a silicon chip.

To make BTO multiferroic, the researchers used a high-power nanosecond pulse laser to create oxygen vacancy-related defects into the material. These defects create ferromagnetic properties in the BTO.

The buffer layers are titanium nitride (TiN) and magnesium oxide (MgO). The TiN is grown as a single crystal on the silicon substrate. The MgO is then grown as a single crystal on the TiN. The BTO, or BTO/LSMO bilayer film, is then deposited on the MgO. The resulting buffer layers allow the multiferroic material to function efficiently without diffusing into the silicon and destroying silicon transistors.

“We’ve already fabricated prototype memory devices using these integrated, multiferroic materials, and are testing them now,” Narayan says. “Then we will begin looking for industry partners to make the transition to manufacturing.”

The work is described in two papers in the Journal of Applied Physics.

Source: North Carolina State Univ.

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研究人员研发了可集成到硅片上的多铁材料与设备来自美国北卡罗莱纳州立大学的科学家们在多铁材料研究上实现了两项重要突破，包括将多铁材料

集成到硅芯片上，该技术将促进电子存储设备的发展。现在，研究人员已经制作了这种设备的实验室模型，并正在对其进行测试。

多铁材料是一种既有铁电性质，又有铁磁性质的材料。北卡罗莱纳州立大学材料科学与工程学院 John C. Fan特聘讲座教授 Jay Narayan博士，同时也是描述

这项研究的两篇论文的主要作者，说“这些多铁材料提供了这样一种可能：电场可以转换材料的磁场，外磁场也可以转换材料的电极。对于下一代的低功耗、高稳定性的记忆存储设备来说，这些材料相当具有吸引力。”

此前，研究人员已经知道可以通过层叠钛酸钡（BTO）和 LSMO来制造多铁材料，BTO具有铁电性质，而 LSMO具有铁磁性质。但是这种“双层”薄膜的大规模应用是不可行的，因为他们不能集成到硅片上，这种薄膜的组成元素会扩散进硅片中。

不过，Naranyan团队的研究工作有两向进步之处：1、他们找到了一种可以赋予BTO铁磁性质的方法，于是多铁性质的实现不再需要 LSMO；2、他们开发出了一种中间层，可以将BTO或是 BTO/LSMO集成到硅片上。

为了实现 BTO的多铁性质，研究人员用大功率的纳秒脉冲激光在材料中制造了氧空位缺陷。正是这些缺陷的存在赋予了 BTO铁磁性质。

缓冲层是氮化钛（TiN）和氧化镁（MgO）。TiN是生长在硅衬底上的单晶体，MgO则是生长在 TiN上的单晶，BTO层或 BTO/LSMO层是沉积在MgO层上的。这种构造使得多铁材料可以有效运作，而不扩散到硅中、不会破坏硅晶体管。

“我们已经制作了基于多铁性材料的实验室存储器，并且正在测试他们，” Narayan如是说，“下一步，我们将会寻求工业合作来将这项技术转化到制造业。”

《应用物理杂志》发表的两篇论文对此项研究做了详细描述。来源：北卡罗莱纳州立大学

Laser-induced graphene “super” for electronics

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An electron microscope image shows the cross section of laser-induced graphene burned into both sides of a polyimide substrate. The flexible material created at Rice Univ. has the potential for use in electronics or for energy storage. Image: Tour Group

Rice Univ. scientists advanced their recent development of laser-induced graphene (LIG) by producing and testing stacked, 3-D supercapacitors, energy storage devices that are important for portable, flexible electronics.

The Rice laboratory of chemist James Tour discovered last year that firing a laser at an inexpensive polymer burned off other elements and left a film of porous graphene, the much-studied atom-thick lattice of carbon. The researchers viewed the porous, conductive material as a perfect electrode for supercapacitors or electronic circuits.

To prove it, members of the Tour group have since extended their work to make vertically aligned supercapacitors with laser-induced graphene on both sides of a polymer sheet. The sections are then stacked with solid electrolytes in between for a multilayer sandwich with multiple microsupercapacitors.

The flexible stacks show excellent energy-storage capacity and power potential and can be scaled up for commercial applications. LIG can be made in air at ambient temperature, perhaps in industrial quantities through roll-to-roll processes, Tour said.

The research was reported in Applied Materials and Interfaces.

Capacitors use an electrostatic charge to store energy they can release quickly, to a camera’s flash, for example. Unlike chemical-based rechargeable batteries, capacitors charge fast and release all their energy at once when triggered. But chemical batteries hold far more energy. Supercapacitors combine useful qualities of both—the fast charge/discharge of capacitors and high-energy capacity of batteries—into one package.

LIG supercapacitors appear able to do all that with the added benefits of flexibility and scalability. The flexibility ensures they can easily conform to varied packages—they can be rolled within a cylinder, for instance—without giving up any of the device’s performance.

“What we’ve made are comparable to microsupercapacitors being commercialized now, but our ability to put devices into a 3-D configuration allows us to pack a lot of them into a very small area,” Tour said. “We simply stack them up.

“The other key is that we’re doing this very simply. Nothing about the process requires a clean room. It’s done on a commercial laser system, as found in routine machine shops, in the open air.”

Ripples, wrinkles and sub-10-nm pores in the surface and atomic-level imperfections give LIG its ability to store a lot of energy. But the graphene retains its ability to move electrons quickly and gives it the quick charge-and-release characteristics of a supercapacitor. In testing, the researchers charged and discharged the devices for thousands of cycles with almost no loss of capacitance.

To show how well their supercapacitors scale up for applications, the researchers wired pairs of each variety of device in serial and parallel. As expected, they found the serial devices delivered double the working voltage, while the parallels doubled the discharge time at the same current density.

The vertical supercapacitors showed almost no change in electrical performance when flexed, even after 8,000 bending cycles.

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Tour said that while thin-film lithium ion batteries are able to store more energy, LIG supercapacitors of the same size offer three times the performance in power (the speed at which energy flows). And the LIG devices can easily scale up for increased capacity.

“We’ve demonstrated that these are going to be excellent components of the flexible electronics that will soon be embedded in clothing and consumer goods,” he said.

Source: Rice Univ.

激光诱导石墨烯对电子工业的重要性

电子显微镜图像显示的是，激光诱导石墨烯侵蚀聚酰亚胺基底两侧的横截面，莱斯大学创造的这一灵活材料有望用在电子工业或能源存储领域。图像提供：Tour Group

莱斯大学科学家通过生产堆叠的三维超电容、能源储能设备并对其进行试验，从而改进了他们最近研发出的激光诱导石墨烯（简称 LIG），而这些设备对便携、灵活的电子产品很重要。

莱斯实验室的化学家詹姆斯•图尔去年发现，向廉价聚合物发射一束激光，也会燃烧掉其他元素，剩下一层多孔石墨烯薄膜，即，久经研究的原子厚层晶格碳。研究人员将这种多空、多产的材料看作是超电容或电子电路使用的完美电极。

为了证明这一点，图尔组的研究人员从此拓展了他们的研究工作，用聚合物两端的激光诱导石墨烯制作垂直对齐的超容器。这些部分之间堆满了固体电解质，就像是多个微超容器的多层次三明治。

这种灵活的堆积显示了完美的储能能力和电能潜力，可以用在商业领域。图尔说，LIG可以在环境温度中产生，或也可以会通过“滚对滚”流程进行工业规模的生产。

《应用材料和界面》杂志（Applied Materials and Interfaces.）道了这一研究的结果。电容器使用静电电荷储藏它们能够快速释放的能量，比如释放给相机的闪光灯等。不像化学合成的可

充电电池，电容器充电速度快，一旦触发，能量就能一次性释放，但是化学电池可存储更多的能量。超级电容将两者的特性结合在了一起——即，电容器的快速充电与放电，以及电池的高储能性。

LIG超容器看似可以做到这一切，得益于灵活性和可扩展性，灵活性确保它们能够适合多种形状——比如它们能够在缸体内滚动，且不用放弃任何一个设备的性能。

“我们的产品可以与商业化微型超容器相匹敌，但是我们将设备转化为三维配置的能力可以使我们把很多这类设备放在一个很小的区域内，”图尔说。“我们就是简单地把它们堆积起来而已。

“另外一个关键就是，我们用了非常简单的方式，整个过程都不需要干净的房间，而是在商业激光系35


统中完成的，就像是在室外常规机器中发现的那样。 LIG表面的波纹、褶皱和不到 10nm的细孔，以及原子水平的不完美，使其能够存储许多能量，但是

石墨烯保留了快速移动电子的能力，也给了它超容器具备的充电-放电特性。在测试中，研究人员对此设备进行了成千上万次的充电和放电，而且电容几乎没有减少。

为了展示他们的超容器如何进行扩展进而应用到实践中，研究人员把每一种设备进行串联和并联配对。正如预期那样，他们发现串联设备可传输两倍的工作电压，而并联设备在相同电流浓度条件下会使释放电的时间翻倍。

垂直超容器显示，收缩时电学性能几乎没有任何变化，甚至弯曲 8000圈还是这样。图尔说，薄膜锂离子电池能够储藏更多的能量，相同尺寸的 LIG超容器提供了三倍的电流性能（电

能流动的速度）。LIG设备能够容易地扩大容量。“我们已经证明，这些会是柔性电子产品重要的一组件，这些电子产品很快会与服装和消费商品相结

合，”他说。来源：莱斯大学

Single-photon emission enhancement

Nanodiamonds have been added to the surface of a new "hyperbolic metamaterial" to enhance the production of single photons, a step toward creating devices aimed at developing quantum computers and communications technologies. Image: Birck Nanotechnology Center

Researchers have demonstrated a new way to enhance the emission of single photons by using "hyperbolic metamaterials," a step toward creating devices in work aimed at developing quantum computers and communications technologies.

Optical metamaterials harness clouds of electrons called surface plasmons to manipulate and control light. Purdue Univ. researchers had previously created "superlattices" from layers of the metal titanium nitride and the dielectric, or insulator, aluminum scandium nitride. Unlike some of the plasmonic components under development, which rely on the use of noble metals such as gold and silver, the new metamaterial is compatible with the complementary metal–oxide–semiconductor manufacturing process used to construct integrated circuits.

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The metamaterial is said to be hyperbolic, meaning it possesses unique properties leading to the increased output of light. In new findings the researchers have demonstrated how attaching nanodiamonds containing "nitrogen-vacancy centers" to the new metamaterial further enhances the production of single photons, workhorses of quantum information processing, which could bring superior computers, cryptography and communications technologies.

"These results indicate that the brightness of the nanodiamond-based single-photon emitter could be substantially enhanced by placing such an emitter on the surface of the hyperbolic metamaterial," said Alexander Kildishev, associate professor of electrical and computer engineering at Purdue. "The single-photon emitters could be used to build highly efficient room temperature CMOS-compatible single-photon sources."

Research findings are detailed in Laser & Photonics Reviews. The work was a collaboration of researchers from Purdue, the Russian Quantum Center, Moscow Institute of Physics and Technology, Lebedev Physical Institute and Photonic Nano-Meta Technologies Inc.

A nitrogen-vacancy center is an atomic-scale defect formed in the diamond lattice by substituting a nitrogen atom for a carbon atom and creating a neighboring void in the lattice. Placing a nanodiamond containing an NV center on the surface of hyperbolic metamaterials not only enhances the emission of photons, but also changes the pattern of light emitted, a trait that could be important for the development of quantum devices, said graduate student Mikhail Y. Shalaginov, the paper's lead author. He and Kildishev are working with a team of researchers led by Vladimir M. Shalaev, scientific director of nanophotonics at Purdue's Birck Nanotechnology Center and a distinguished professor of electrical and computer engineering, and Alexandra Boltasseva, an associate professor of electrical and computer engineering. Profs. Shalaev, Kildishev and Boltasseva are a part of a Purdue "preeminent team" working on quantum photonics.

Because the studied system represents a stable source of single photons that functions at room temperature, it is potentially practical for commercial applications. When exposed to a laser light, the system rises from its "ground state" to an excited state, which causes it to spontaneously emit a photon.

"We are interested in causing it to emit faster so that we can increase the rate of these photons coming out," Kildishev said.

Findings show the system is capable of producing single photons faster, in larger quantities, and more directionally.

Metamaterials have engineered surfaces that contain features, patterns or elements, such as tiny antennas or alternating layers of nitrides that enable unprecedented control of light. Constructed of artificial atoms and molecules, the optical metamaterials owe their unusual potential to precision engineering on the scale of nanometers.

Quantum computers would take advantage of phenomena described by quantum theory called "superposition" and "entanglement." Instead of only the states of one and zero that exist in conventional computers, there are many possible "superposition quantum states." Computers based on quantum physics would have quantum bits, or "qubits," increasing the computer's capacity to process, store and transmit information. The nitrogen-vacancy also makes it possible to potentially record information based on the nuclear or electron "spin" state of the center, which is promising for quantum computing. The spin can be either "up" or "down"—forming the quantum superposition of the up and down states—representing a new technology for processing information.

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Future research may include work to improve the system with devices that combine the hyperbolic metamaterial with nanoantennas and optical waveguides to increase its efficiency and make it more compact. The ongoing work also may strive to improve the "spin properties" of the system with nitrogen-vacancies and to study the optical contrast between the up and down states.

Source: Purdue Univ.

单光子发射增强

纳米钻石已经被添加在“双曲线超材料”表面，目的是增加单光子产量，向创造用于研发量子计算机和通讯技术的设备迈进了一步。图像提供：桦树纳米技术中心

研究人员运用“双曲线超材料”展示了一种增强单光子发射的新方法，向创造用于研发量子计算机和通讯技术的设备迈进了一步。

光学超材料利用被称为表面等离子体的电子云来操控光。之前，普渡大学研究人员曾利用金属氮化钛、介电、绝缘子、氮化铝钪层创造了“超晶格”。正在研发中的一些等离子组件使用的是金、银之类的贵金属，与此不同的是，新型超材料与用来建造集成电路的互补金属氧化半导体（以下简称 CMOS）制造过程相容。

超材料据说是双曲线状的，这意味着超材料具备能够增加电产量的独特性质。在新的发现中，研究人员展示包括“氮空位中心”在内的纳米钻石附加在新的超材料上，如何进一步增加单光子的产量和量子信息处理主力，可促进高级计算机、加密技术和通信技术。

“这些结果说明，一纳米钻石为基础的单光子发射体的亮度能够通过把发射器放在双曲线超材料表面而大量增强，”普渡大学电子计算机工程副教授Alexander Kildishev说道。“单光子发射器能够用来建立高效率的 CMOS兼容的室温单光子源。”

研究人员的研究结果详情刊载于《激光与电子学评论》（Laser & Photonics Reviews），这项研究工作由来自普渡大学、俄罗斯量子中心、莫斯科物理与技术研究所、列别捷夫物理研究所和光学纳米-超材料技术公司（Photonic Nano-Meta Technologies Inc.）的研究人员合作完成。

氮空位中心属于原子尺度缺陷，是用氮原子代替碳原子并在晶格中形成一个邻近空位，而在金刚石晶格中形成的缺陷。论文的主要作者、研究生Mikhail Y. Shalaginov说，将包含NV中心的纳米钻石放在双曲线超材料表面上，不仅增强了光子的发射，还改变了发光模式，这一特征对量子设备的发展至关重要。

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他和 Kildishev与一组由 Vladimir M. Shalaev和 Alexandra Boltasseva领导的研究人员进行了合作。其中，Vladimir M. Shalaev为普渡桦树纳米中心的纳米光学科学主任、电子计算机工程优秀教授；Alexandra Boltasseva为电子计算机工程副教授。Shalaev教授、Kildishev教授和 Boltasseva教授都属于负责量子电子学研究的普渡“杰出研究组”的成员。

因为所研究的系统代表了单光子的一个稳定源，可在室内温度下运行，所以其或对对商业应用有实用性。这一系统暴露在激光下时，从“基态”上升为兴奋状态，从而引发其同时释放一个光子。

Dishevel说：“我们感兴趣的是要让其进行更快地释放，这样我们就能够增加这些光子出来的速度。”

这些发现显示，这一系统能够更直接更快速产生更多单光子。超材料已经设计了包含特征、样式或者元素在内的表面，例如小天线或者互层氮化物，可使前所未有

的光控制得以实现。光学超材料建立人工原子和分子，其不寻常的潜力要归功于纳米规模上的精密工程。量子计算机将利用量子理论描述的所谓“叠加”和“纠缠”的现象。传统计算机不仅存在一个或零个

状态，而是有许多可能的“叠加量子状态”。建立在量子物理学上的计算机将含有量子比特，增加了电脑处理、存储和传播信息的能力，氮晶格空位也使根据核内或电子中心的“自旋”状态记录信息变得可能，这使量子计算机变得有前途。旋转可能是“向上的”，也可能是“向下的”——形成上下状态的量子叠加，代表了一种新的信息处理技术。

将来的研究可能涉及使用将双曲线超材料与纳米天线和光学波导相结合的设备来改善这一系统，进而增加效率，使它更加紧凑。继续进行的研究也可能会力求使用氮空位来提高这一系统的“旋转特性”，并研究上下两种状态的光学对比。

来源：普渡大学

Rice-sized laser bodes well for quantum computing

Princeton Univ. researchers have built a rice grain-sized microwave laser. Image: Jason Petta, Princeton Univ.

Princeton Univ. researchers have built a rice grain-sized laser powered by single electrons tunneling through artificial atoms known as quantum dots. The tiny microwave laser, or "maser," is a demonstration of the fundamental interactions between light and moving electrons.

The researchers built the device—which uses about one-billionth the electric current needed to power a hair dryer—while exploring how to use quantum dots, which are bits of semiconductor material that act like single atoms, as components for quantum computers.

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"It is basically as small as you can go with these single-electron devices," said Jason Petta, an associate professor of physics at Princeton who led the study, which was published in Science.

The device demonstrates a major step forward for efforts to build quantum-computing systems out of semiconductor materials, according to co-author and collaborator Jacob Taylor, an adjunct assistant professor at the Joint Quantum Institute, Univ. of Maryland-NIST. "I consider this to be a really important result for our long-term goal, which is entanglement between quantum bits in semiconductor-based devices," Taylor said.

The original aim of the project was not to build a maser, but to explore how to use double quantum dots—which are two quantum dots joined together—as quantum bits, or qubits, the basic units of information in quantum computers.

"The goal was to get the double quantum dots to communicate with each other," said Yinyu Liu, a physics graduate student in Petta's laboratory. The team also included graduate student Jiri Stehlik and associate research scholar Christopher Eichler in Princeton's Dept. of Physics, as well as postdoctoral researcher Michael Gullans of the Joint Quantum Institute.

Because quantum dots can communicate through the entanglement of light particles, or photons, the researchers designed dots that emit photons when single electrons leap from a higher energy level to a lower energy level to cross the double dot.

Each double quantum dot can only transfer one electron at a time, Petta explained. "It is like a line of people crossing a wide stream by leaping onto a rock so small that it can only hold one person," he said. "They are forced to cross the stream one at a time. These double quantum dots are zero-dimensional as far as the electrons are concerned—they are trapped in all three spatial dimensions."

The researchers fabricated the double quantum dots from extremely thin nanowires (about 50 nm in diameter) made of a semiconductor material called indium arsenide. They patterned the indium arsenide wires over other even smaller metal wires that act as gate electrodes, which control the energy levels in the dots.

To construct the maser, they placed the two double dots about 6 mm apart in a cavity made of a superconducting material, niobium, which requires a temperature near absolute zero, around -459 F. "This is the first time that the team at Princeton has demonstrated that there is a connection between two double quantum dots separated by nearly a centimeter, a substantial distance," Taylor said.

When the device was switched on, electrons flowed single-file through each double quantum dot, causing them to emit photons in the microwave region of the spectrum. These photons then bounced off mirrors at each end of the cavity to build into a coherent beam of microwave light.

One advantage of the new maser is that the energy levels inside the dots can be fine-tuned to produce light at other frequencies, which cannot be done with other semiconductor lasers in which the frequency is fixed during manufacturing, Petta said. The larger the energy difference between the two levels, the higher the frequency of light emitted.

Source: Princeton Univ.

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米粒大小的激光的量子计算应用前景良好

普林斯顿大学的研究人员已经建立了一种米粒大小的微波激光。图片提供：普林斯顿大学 Jason Petta普林斯顿大学的研究人员已经制造出一种大米粒大小的激光，该激光由单电子驱动，可以穿过叫做

量子点的人造原子。这种微小的微波激光，或称微波激射器，是光和移动电子之间基本相互作用的证明。研究人员制造除的这种设备，只需要用 10亿分之一的电流，就可以启动吹风机；研究人员同时还研

究了如何使用量子点作为量子计算的元件。量子点就是半导体材料的碎片，作用和单原子一样。普林斯顿大学物理学副教授 Jason Petta主导了此项研究，研究结果发表在《科学》杂志上，Jason Pett

说，量子点很小，人们可以随意处理这些单电子设备。Jacob Taylor是此项研究的共同作者和合作者，同时也是马里兰大学-美国国家标准与技术研究院联合

量子研究所的兼任助理教授，据他所说，这种单电子设备表明，人们向使用半导体材料建立量子计算系统又走近了一步。他说：“我认为这将是我们长期目标的一个十分重要的结果，这是半导体材料设备中的量子位之间的纠缠。”

该研究项目的初始目标不是建立微波激射器，而是研究如何使用双量子点，双量子点是两个量子点结合在一起的量子点，就像量子位，或量子比特一样，是量子计算中信息的基本单位。

Petta实验室的物理研究所Yinyu Liu说，项目的目标是得到双量子点，让双量子点相互联系。参与研究小组的还有研究生 Jiri Stehlik、普林斯顿大学物理系副研究学者 Christopher Eichler，以及联合量子研究所博士后研究学者Michael Gullans。

因为量子点可以通过光粒子，或者光粒子的纠缠，相互联系，所以研究人员设计了量子点，其可以在单电子从高能量等级跳向低能量等级，从而穿过双量子点时，散发光量子。

Petta解释说，每个双量子点一次可以转换一个电子。他说，这就像一队人，通过跳到一个只能容纳一个人的石头上过河一样。这就要求一次只有一个人可以过河。对于电子来说，这些双量子点是零维的，他们被困在所有的三维空间里。

研究人员从极其纤细的纳米线（直径大于 50纳米）中制造出来双量子点，纳米线是由砷化铟半导体材料制成的。研究人员在其它更小的金属线上制造砷化铟线，金属线作为闸极，可以控制量子点的能量等级。

为了制造微波激射器，研究人员将两个双量子点在反应腔内分开大概 6毫米，反应腔由超导体材料铌组成，温度要求在绝对零度附近，大概是-459华氏度。这是普林斯顿大学研究小组第一次表明两个双量子点在分开将近 1厘米时还有联系，1厘米算是相当大的距离了。

当打开设备时，电子排成单行穿过每个双量子点，导致电子在波谱的微波区域发出光量子。这些光量子在腔末端反射反射光，从而形成微波光的相干光束。

Petta说，此新型微波激射器的一个优点是：量子点内部的能量等级可以调整，从而在其他频率下产41


生光，这是其他半导体激光不能做到的，其他半导体激光在制造过程中频率都是固定的。两个能量等级的能量差异越大，反射出的光的频率越高。

来源：普林斯顿大学

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中国材料研究学会 · web viewthe research was reported in applied materials and interfaces....

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