工程师的新发明——高速纳米雪崩（原创）

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       作为他的博士研究的一部分，Charles McLaren发现，在玻璃上应用直流电场可以降低了它的熔化温度。在他们的实验中，他们在阴极和阳极之间放置了一块玻璃，然后在玻璃上施加了稳定的压力，同时逐渐加热。信用：学术形象 查尔斯•麦克拉伦
        利哈伊大学材料科学与工程博士,去年秋天来他来到德国马尔堡大学做学期研究，他的语言能力明显落后于他的科学能力。 “这是我第一次去德国,我几乎没有说一个字的德语,”他承认。

    迈凯轮在马尔堡交换研究的主要目的是为了了解更多关于在一个复杂的过程,涉及玻璃发生强烈的电和热的条件下的转换。对这些机制新的理解能带来更多的节能玻璃制造,甚至玻璃超级电容器，都超越现在用于电动汽车和太阳能的性能。

  “这项技术与公司寻求下一波的便携式,可靠的能源有关，”Himanshu Jain说，他是迈凯轮车队的顾问，利哈伊材料科学和工程学的T.L.钻石特聘教授和格拉斯国际新功能材料研究所的主任。“在使用玻璃的电力储存的突破可能会释放在运输和能源部门的创新的洪流，甚至支持努力遏制全球变暖。”

   作为他的博士研究的一部分,麦克拉伦发现将直流电场应用在玻璃上可以降低它的熔化温度。在他们的实验中，他们把一块玻璃在阴极和阳极之间，然后施加压力稳定在玻璃上而逐渐加热。 麦克拉伦和Jain与科罗拉多大学的同事们一起,在物理快报公布了他们的发明。

这一发现是耐人寻味的。除了在较低的温度和减少能源需求下使玻璃配方可行，设计师在使用电流进行玻璃制造时将会使用一个工具进行精确操作，而不仅仅使用加热的方式。

  “举个例子，你可以做一个用玻璃做个面具，来将电场应用于微米尺度上，”Jain说。 “这将允许你在一个更为选择的方式来变形更加精确的玻璃并软化它而不是你用热分布在整个玻璃上。”

  虽然迈凯轮和Jain已经分离现象，并确定了拨号变量方法的最优结果,他们还不完全理解其背后的机制。迈凯轮和Jain已经在马尔堡大学的博纳的博士的计算机上工作，他们曾发现采用电热极化的玻璃的一些显著特点，一种利用操纵温度和电流来创建通常在惰性玻璃种的电荷的技术。这个过程提供有用的光学和生物活性玻璃的品质。

  罗琳邀请麦克拉伦在马尔堡花一个学期来分析电热极化下玻璃的行为，是否会透露更多有关基础科学是迈凯轮和Jain在利哈伊实验室的观察内容。

高速雪崩

  麦克拉伦在马尔堡的工作揭示了一个两步方法，一个薄的玻璃碎片最近的阳极，称为耗尽层，变得比玻璃上的其余部分更耐电性，因为玻璃中的碱金属离子迁移。其次是一个灾难性的变化层,称为介质击穿，这极大地增加了其导电性。迈凯轮将介质击穿的过程比作一个高速雪崩，利用光谱分析与电热极化的一种方式，观察在慢速中发生什么。

“在德国的结果给了我们一个很好的模型吗，什么是在电场引起的软化，我们在这里做了。它告诉我们，介质击穿可以开始的开始条件。”麦克拉伦解释说。

“查理在马尔堡的工作帮助我们看到的动力学过程，”Jain说。“在利哈伊这我们意外的在实验中看到了它的发生，但是我们现在有一个方法分离出具 体发生的耗尽层。”

麦克拉伦、Jain和他们马尔堡团队成员在2016年9月《电化学学会》发表了他们的研究结果。

“马尔堡之旅对个人是非常有用的专业和启发，”麦克拉伦说。“科学上，它总是很好地看到你的工作的另一个制高点，并看到其他研究组解释数据或执行的实验。在马尔堡我们团队非常勤奋,我很喜欢，他们非常支持彼此。 如果有人提交了一篇论文，整个团队将烧烤庆祝，他们总是给对方反馈工作。 有时它是残酷的诚实，他们没有忍住，但他们是你需要听到的东西。”

“在马尔堡工作还教我如何与一个完全不同的人交流，”他继续说，“当你有机会和其他文化密切起来时你可以最好的看到你自己的文化的差异。 这总是一个全新的视角。”

来源：原创

英文：
Engineers discover a high-speed nano-avalanche[size=1.4]

As part of his doctoral research, Charles McLaren discovered that applying a direct current field across glass reduced its melting temperature. In their experiments, they placed a block of glass between a cathode and anode, and then exerted steady pressure on the glass while gradually heating it. Credit: Douglas Benedict of Academic Image

Charles McLaren, a doctoral student in materials science and engineering at Lehigh University, arrived last fall for his semester of research at the University of Marburg in Germany with his language skills significantly lagging behind his scientific prowess. "It was my first trip to Germany, and I barely spoke a word of German," he confessed.

The main purpose of McLaren's exchange study in Marburg was to learn more about a complex process involving transformations in glass that occur under intense electrical and thermal conditions. New understanding of these mechanisms could lead the way to more energy-efficient glass manufacturing, and even glass supercapacitors that leapfrog the performance of batteries now used for electric cars and solar energy.

"This technology is relevant to companies seeking the next wave of portable, reliable energy," said Himanshu Jain, McLaren's advisor and the T. L. Diamond Distinguished Chair in Materials Science and Engineering at Lehigh and director of its International Materials Institute for New Functionality in Glass. "A breakthrough in the use of glass for power storage could unleash a torrent of innovation in the transportation and energy sectors, and even support efforts to curb global warming."

As part of his doctoral research, McLaren discovered that applying a direct current field across glass reduced its melting temperature. In their experiments, they placed a block of glass between a cathode and anode, and then exerted steady pressure on the glass while gradually heating it. McLaren and Jain, together with colleagues at the University of Colorado, published their discovery in Applied Physics Letters.

The implications for the finding were intriguing. In addition to making glass formulation viable at lower temperatures and reducing energy needs, designers using electrical current in glass manufacturing would have a tool to make precise manipulations not possible with heat alone.

"You could make a mask for the glass, for example, and apply an electrical field on a micron scale," said Jain. "This would allow you to deform the glass with high precision, and soften it in a far more selective way than you could with heat, which gets distributed throughout the glass."

Though McLaren and Jain had isolated the phenomenon and determined how to dial up the variables for optimal results, they did not yet fully understand the mechanisms behind it. McLaren and Jain had been following the work of Dr. Bernard Roling at the University of Marburg, who had discovered some remarkable characteristics of glass using electro-thermal poling, a technique that employs both temperature manipulation and electrical current to create a charge in normally inert glass. The process imparts useful optical and even bioactive qualities to glass.

Roling invited McLaren to spend a semester at Marburg to analyze the behavior of glass under electro-thermal poling, to see if it would reveal more about the fundamental science underlying what McLaren and Jain had observed in their Lehigh lab.

A high-speed avalanche

McLaren's work in Marburg revealed a two-step process in which a thin sliver of the glass nearest the anode, called a depletion layer, becomes much more resistant to electrical current than the rest of the glass as alkali ions in the glass migrate away. This is followed by a catastrophic change in the layer, known as dielectric breakdown, which dramatically increases its conductivity. McLaren likens the process of dielectric breakdown to a high-speed avalanche, and using spectroscopic analysis with electro-thermal poling as a way to see what is happening in slow motion.

"The results in Germany gave us a very good model for what is going on in the electric field induced softening that we did here. It told us about the start conditions for where dielectric breakdown can begin," explained McLaren.

"Charlie's work in Marburg has helped us see the kinetics of the process," Jain said. "We could see it happening abruptly in our experiments here at Lehigh, but we now have a way to separate out what occurs specifically with the depletion layer."

McLaren, Jain, Roling and his Marburg team members published their findings in the September 2016 issue of theJournal of Electrochemical Society.

"The Marburg trip was incredibly useful professionally and enlightening personally," said McLaren. "Scientifically, it's always good to see your work from another vantage point, and see how other research groups interpret data or perform experiments. The group in Marburg was extremely hardworking, which I loved, and they were very supportive of each other. If someone submitted a paper, the whole group would have a barbecue to celebrate, and they always gave each other feedback on their work. Sometimes it was brutally honest—they didn't hold back—but they were things you needed to hear."

"Working in Marburg also showed me how to interact with a completely different group of people," he continued, "and you see differences in your own culture best when you have the chance to see other cultures close up. It's always a fresh perspective."