Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electrons Get Confused

04.11.2010
HZB researchers may have observed the fastest melting of all time

Scientists from Helmholtz-Zentrum Berlin (HZB) observed exotic be-haviour from beryllium oxide (BeO) when they bombarded it with high-speed heavy ions: After being shot in this way, the electrons in the BeO appeared “confused”, and seemed to completely forget the material properties of their environment.


The K1-XV-line-spectrum of beryllium-oxide. Picture: HZB/Schiwietz

The researchers’ measurements show changes in the electronic structure that can be explained by extremely rapid melting around the firing line of the heavy ions. If this interpre-tation is correct, then this would have to be the fastest melting ever observed. The researchers are publishing their results in Physical Review Letters (DOI: 10.1103/ Phys.Rev.Lett.105, 187603 (2010)).

In his experiments, Prof. Dr. Gregor Schiwietz and his team irradiated a beryllium oxide film with high-speed heavy ions of such strong charge that they possessed maximum smashing power. Unlike most other methods, the energy of the heavy ions was chosen so that they would interact chiefly with their outer valence electrons. As heavy ions penetrate into a material, there are typically two effects that occur immediately around the fired ions: the electrons in the immediate surroundings heat up and the atoms become strongly charged. At this point, Auger electrons are emitted, whose energy levels are measurable and show up in a so-called line spectrum. The line spectrum is characteristic for each different material, and normally changes only slightly upon bombardment with heavy ions.

As a world’s first, the HZB researchers have now bombarded an ion crystal (BeO), which has insulator properties, with very high-speed heavy ions (xenon ions), upon which they demonstrated a hitherto unknown effect: The line spectrum of the Auger electrons changed drastically – it became “washed out”, stretching into higher energies. Together with a team of physicists from Poland, Serbia and Brazil, the researchers observed distinctly metallic signatures from the Auger electrons emitted by the heated BeO material. The Auger electrons appeared to have completely “forgotten” their insulator properties. The researchers see this as clear evidence that the band structure breaks down extremely rapidly when the BeO is bombarded with heavy ions – in less than about 100 femtoseconds (one femtosecond is a millionth of a millionth of a millisecond). This breakdown is triggered by the high electron temperatures of up to 100000 Kelvin. In the long term, however, the material of the otherwise cold solid remains overall intact.

The HZB researchers’ results deliver strong evidence of ultra-fast melting processes around the firing line of the heavy ions. This melting is followed by annealing that deletes all permanent signs of the melting process. Prof. Schiwietz hopes to find other ionic crystals that exhibit the same rapid melting process, but in which the annealing process is suppressed. If any are found, then a conceivable application would be programming at femtosecond speeds.

The Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) operates and develops large scale facilities for research with photons (synchrotron beams) and neutrons. The experimental facilities, some of which are unique, are used annually by more than 2,500 guest researchers from universities and other research organisations worldwide. Above all, HZB is known for the unique sample environments that can be created (high magnetic fields, low temperatures). HZB conducts materials research on themes that especially benefit from and are suited to large scale facilities. Research topics include magnetic materials and functional materials. In the research focus area of solar energy, the development of thin film solar cells is a priority, whilst chemical fuels from sunlight are also a vital research theme. HZB has approx.1,100 employees of whom some 800 work on the Lise-Meitner Campus in Wannsee and 300 on the Wilhelm-Conrad-Röntgen Campus in Adlershof.

HZB is a member of the Helmholtz Association of German Research Centres, the largest scientific organisation in Germany.

Franziska Rott | Helmholtz-Zentrum
Further information:
http://www.helmholtz-berlin.de/

Further reports about: BeO HZB beryllium oxide electrons magnetic field magnetic material

More articles from Materials Sciences:

nachricht Switched-on DNA
20.02.2017 | Arizona State University

nachricht Using a simple, scalable method, a material that can be used as a sensor is developed
15.02.2017 | University of the Basque Country

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>