钙钛矿锰氧化物的新特性
文章来源:未知 文章作者:enread 发布时间:2014-07-26 08:14 字体: [ ]  进入论坛
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A novel combination of microscopy(显微镜检查) and data processing has given researchers at the Department of Energy's Oak Ridge1 National Laboratory an unprecedented2 look at the surface of a material known for its unusual physical and electrochemical properties. The research team led by ORNL's Zheng Gai examined how oxygen affects the surface of a perovskite(钙钛矿) manganite, a complex material that exhibits dramatic magnetic and electronic behavior. The new avenue to understand surface behavior could benefit researchers who are interested in using a wide range of correlated oxide3 materials for applications such as solid fuel cells or oxygen sensors4.
 
"Surface properties are key for any sensitive application, because the surface controls the interaction with the outside world," said coauthor Art Baddorf.
 
The team's results, published in Nature Communications, underscore why the materials are called "strongly correlated:" Because the chemical and physical functionalities are coupled, any minor5 change can influence the entire system.
 
"It's like the material has many knobs, and if you turn one, all the properties change," Gai said. "You turn a different knob and the whole thing changes again. It turns out the surface is another knob -- you can use it to change the properties."
 
The researchers used high-resolution scanning tunneling microscopy to generate images of the manganite surface -- down to the level of 30 picometers(微微米). A picometer is one trillionth of a meter. They then processed the imaging data to determine the position of each atom and calculate the angles between the atoms.
 
"Knowing where the atoms are positioned shows how they are interacting," Baddorf said.
 
The resulting "distortion maps" brought into view structural6 areas called domains7 that were not easily identified in the raw images. The maps clearly showed how the presence of oxygen atoms forced the atoms into a checkerboard pattern known as a Jahn-Teller distortion. Gai says the team's study is the first time the phenomenon has been observed on a material's surface.
 
"The oxygen totally changes the surface energy," Gai said. "Once you introduce oxygen, the electrons don't like to form a straight line; they zigzag8 to get to a lower energy state. This distortion is a very common concept in bulk materials, but nobody has been able to show this effect on the surface before."


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1 ridge KDvyh     
n.山脊;鼻梁;分水岭
参考例句:
  • We clambered up the hillside to the ridge above.我们沿着山坡费力地爬上了山脊。
  • The infantry were advancing to attack the ridge.步兵部队正在向前挺进攻打山脊。
2 unprecedented 7gSyJ     
adj.无前例的,新奇的
参考例句:
  • The air crash caused an unprecedented number of deaths.这次空难的死亡人数是空前的。
  • A flood of this sort is really unprecedented.这样大的洪水真是十年九不遇。
3 oxide K4dz8     
n.氧化物
参考例句:
  • Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
  • How can you get rid of this oxide coating?你们该怎样除去这些氧化皮?
4 sensors 029aee483db9ae244d7a5cb353e74602     
n.传感器,灵敏元件( sensor的名词复数 )
参考例句:
  • There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
  • Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时,有很大变化。 来自辞典例句
5 minor e7fzR     
adj.较小(少)的,较次要的;n.辅修学科;vi.辅修
参考例句:
  • The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
  • I gave him a minor share of my wealth.我把小部分财产给了他。
6 structural itXw5     
adj.构造的,组织的,建筑(用)的
参考例句:
  • The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
  • The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。
7 domains e4e46deb7f9cc58c7abfb32e5570b6f3     
n.范围( domain的名词复数 );领域;版图;地产
参考例句:
  • The theory of thermodynamics links the macroscopic and submicroscopic domains. 热力学把宏观世界同亚微观世界联系起来。 来自辞典例句
  • All three flow domains are indicated by shading. 所有三个流动区域都是用阴影部分表示的。 来自辞典例句
8 zigzag Hf6wW     
n.曲折,之字形;adj.曲折的,锯齿形的;adv.曲折地,成锯齿形地;vt.使曲折;vi.曲折前行
参考例句:
  • The lightning made a zigzag in the sky.闪电在天空划出一道Z字形。
  • The path runs zigzag up the hill.小径向山顶蜿蜒盘旋。
TAG标签: surface oxygen materials
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