⾦属氢不会吧？最多是个半导体！
4G光元：2019年7⽉8⽇ SOLEIL亮眼的例⼦：在SOLEIL上发现了⾦属氢？
多年来，许多物理学家都声称他们可以通过努⼒地将氢转化为⾦属 -但到⽬前为⽌，没有⼈能够说服持怀疑态度的竞争对⼿。现在法国的研究⼈员认为，他们终于找到了令⼈信服的转型证据，建⽴了新的装置来加压和观察微⼩的氢样品。然⽽，该领域的其他⼈仍然表⽰怀疑，认为法国集团报告的红外数据本⾝并不⾜以证明 - ⽽且所需要的是电导率的测量。
专家们毫不怀疑氢⽓在受到很⾼压⼒时应该成为⾦属。理论告诉我们，压⼒可以从单个原⼦或分⼦的范围中释放电⼦，使它们能够⾃由地通过材料传播（传导）。实际上，已经观察到许多绝缘体正在进⾏转变 - 例如，分⼦氧在⼤约20年前被证明在⼤⽓压⼒约为100万倍（约100 GPa）时变成⾦属。“⽆可争议的是，⾦属氢⽓应该是存在的，”法国能源机构CEA的弗洛朗·奥切利和保罗·杜马斯在最近上传到arXiv的⼀篇论⽂中写道。
⾦属氢的发现当然是令⼈兴奋的。⾦属氢可以具有许多显着的性质，包括在室温下是超导体。研究它的⾏为也可能导致对⽊星和其他⽓体巨⾏星内部条件的新见解，因为它预测了那⾥应该有⼤量的⾦属氢。
⾮常困难和有争议
广州在职研究生
制造⾦属氢已被证明是极其困难和有争议的。⾃1935年预测以来，研究⼈员试图在实验室中通过在两颗钻⽯的尖端之间挤压微⼩的氢⽓样本来创建它。这些微型铁砧可以提供数百吉帕斯卡的压⼒，但结果往往含糊不清。2016年，美国哈佛⼤学的两位研究⼈员报告称制造的⾦属氢为500 GPa。然⽽，其他⼈则质疑该团队是否达到如此⾼的压⼒。
Loubeyre及其同事并不是搜索的新⼿。2002年，他们使⽤可见光来观察氢样品的变化，它们压缩到320 GPa。当他们提⾼压⼒时，他们看到固态氢的电⼦带隙按⽐例下降。通过将线外推到更⾼的压⼒，他们认为它应该在⼤约450 GPa时达到零。此时氢会变成⾦属，因为它的电⼦会⾃由地进⼊导带。
为了达到这个压⼒，该团队开发了⼀种新型的“环形”砧座，其中样品被挤压在两个由环形凹陷环绕的微⼩平⾯之间。他们说，这可以产⽣⾼达⾄少600 GPa的压⼒。他们还设计并制造了⼀个红外显微镜，可以与同步加速器源强烈辐射下的低温恒温器⼀起部署。
我们显⽰在425 GPa附近从绝缘体分⼦固体氢到⾦属氢的⼀级相变
因人而异 英语
Paul Loubeyre，Florent Occelli和Paul Dumas该团队将他们的环形铁砧放在80 K的氢⽓中，并在巴黎郊区的SOLEIL同步加速器上⽤光束线显微镜。在约425GPa的压⼒下，他们观察到否则将通过样品的红外光⼏乎被完全吸收。他们说，这证明了带隙已经结束。他们补充说，他们的结果与理论家在2015
大学英语成绩查询年做出的预测⾮常吻合。“我们在他们的论⽂中写道，”我们展⽰了从绝缘体分⼦固体氢到⾦属氢的425 GPa附近的⼀阶相变。
阅读更多告诉我们你的⾦属
其他研究⼈员表⽰欢迎⼯作的新进展，但有些⼈并不完全相信。华盛顿卡内基科学研究所的亚历⼭⼤·贡查罗夫说：“我认为该论⽂包含了关于氢⽓带隙闭合的良好证据。” “有些解释可能不正确，有些数据可能需要更好，但我普遍相信这是有效的。”尽管如此，他认为证据不是不透⽔的，认为氢⽓带宽但⾮零带隙可能已成为⼀个⾮常窄的带隙半导体，⽽不是⾦属。
德国美因茨马克斯普朗克化学研究所的Mikhail Eremets对此表⽰赞同，并认为缩⼩带隙并不构成“⾦属化的直接证据”。他说，真正需要的是测量氢的电导率。他补充说，他和他的同事两年前进⾏了这样的测量，结果显⽰氢⽓在⼤约360 GPa时开始传导（如“半⾦属”），导电率随压⼒增加⽽强烈增加。他们还测量了拉曼光谱，确定氢是否处于分⼦状态。“我们的数据可能与Loubeyre等⼈的红外数据相辅相成”他说，“但他们完全⽆视这项⼯作。”
dHas metallic hydrogen been made at long last?
08 Jul 2019
Shining example: has metallic hydrogen been spotted at SOLEIL? (Courtesy: C Kermarrec/Synchrotron SOLEIL/CC
Shining example: has metallic hydrogen been spotted at SOLEIL? (Courtesy: C Kermarrec/Synchrotron SOLEIL/CC BY-SA 4.0)
Numerous physicists over the years have claimed they can turn hydrogen into a metal by squeezing it extremely hard –but none so far have managed to persuade sceptical rivals. Now rearchers in France reckon they have finally found convincing evidence for the transformation, having built new devices for pressurizing and obrving tiny samples of hydrogen. Yet others in the field remain doubtful, arguing that infrared data reported by the French group does not on its own constitute adequate proof – and that what is needed are measurements of conductivity.siss
chine manExperts have little doubt that hydrogen should become a metal when subject to very high pressures. Theory tells us that pressure frees electrons from the confines of individual atoms or molecules, allowing them to freely propagate through the material. Indeed, many insulators have been obrved making the transition – molecular oxygen, for example, was shown about 20 years ago to become a metal at around one million times atmospheric pressure (about 100 GPa). “Indisputably, metal hydro
gen should exist,” write Paul Loubeyre, Florent Occelli and Paul Dumas of the French energy agency CEA in a
paper
recently uploaded to arXiv.
后备箱英文
Metallic hydrogen could have many striking properties including being a superconductor at room temperature. Studying its behaviour could also lead to new insights about conditions inside Jupiter and other gas-giant planets, given its predicted abundance there.
Extremely difficult and controversial
But making metallic hydrogen has proven extremely difficult and controversial. Since it was predicted in 1935, rearchers have tried to create it in the lab by squeezing tiny samples of hydrogen gas between the tips of two diamonds. The miniature anvils can deliver pressures of hundreds of gigapascals, but the results are often ambiguous. In 2016, two rearchers at Harvard University in the US
reported making metallic hydrogen at 500 GPa
. Others, however, questioned whether such a high pressure was reached by the team.
Loubeyre and colleagues are not newcomers to the arch. In 2002 they ud visible light to obrve changes in a hydrogen sample that they compresd up to 320 GPa. As they raid the pressure, they saw that the electronic bandgap of solid hydrogen dropped proportionally. By extrapolating the line to higher pressure they reckoned it should have reached zero at about 450 GPa. At this point hydrogen would become a metal becau its electrons would freely enter the conduction band.
To reach this pressure, the team developed new kind of “toroidal” anvil cell in which samples are squeezed between two tiny flat surfaces surrounded by ring-shaped depressions. This, they say, can generate pressures of up to at least 600 GPa. They also designed and built an infrared microscope that can be deployed together with a cryostat within the inten radiation from a synchrotron source.
华侨外国语学校We show a first order pha transition near 425 GPa from insulator molecular solid hydrogen to metal hydrogen
背景调查怎么做Paul Loubeyre, Florent Occelli and Paul Dumas
The team put their toroidal anvil, containing hydrogen at 80 K, and microscope in a beamline at the SOLEIL synchrotron on the outskirts of Paris. At pressures of about 425 GPa they obrved that the infrared light that would otherwi pass through the sample was almost completely absorbed. This is proof, they say, that the bandgap was clod. They add that their results cloly match predictions made by theorists in 2015. “We show a first order pha transition near 425 GPa from insulator molecular solid hydrogen to metal hydrogen,” they write in their paper.
READ MORE
Show us your metal
Other rearchers welcome the latest work but some are not entirely convinced. “I think that the paper contains good evidence about the band gap closure in hydrogen,” says
Alexander Goncharov
of the Carnegie Institution for Science in Washington. “Some interpretations may be incorrect, and some data could be better, but I generally trust that this is valid.” Nevertheless, he reckons that the evidence isn’t watertight, arguing that with a narrow but non-zero band-gap the hydrogen might have become a very narrow band-gap miconductor, rather than a metal.
单价英语
摘要英文翻译Mikhail Eremets
of the Max Planck Institute for Chemistry in Mainz, Germany, agrees, and argues that the reduction of the band gap doesn’t constitute “direct evidence of metallization”. What’s really needed, he says, is a measurement of the hydrogen’s electrical conductivity. He adds that he and his colleagues carried out such a measurement two years ago, showing that hydrogen starts to conduct (like a “mimetal”) at about 360 GPa and that conductivity increas strongly with pressure. They also measured Raman spectra, which determine whether hydrogen is in a molecular state. “Our data could be complimentary to Loubeyre et al’s infrared data” he says, “but [they] completely ignore this work.”
