Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Watching the hidden life of materials

28.10.2014

Ultrafast electron diffraction experiments open a new window on the microscopic world

Researchers at McGill University have succeeded in simultaneously observing the reorganizations of atomic positions and electron distribution during the transformation of the “smart material” vanadium dioxide (VO2) from a semiconductor into a metal – in a time frame a trillion times faster than the blink of an eye. 


Prof. Siwick tweaking up the laser in his McGill University lab. CREDIT: Allen McInnis for McGill University

The results, reported Oct. 24 in Science, mark the first time that experiments have been able to distinguish changes in a material’s atomic-lattice structure from the relocation of the electrons in such a blazingly fast process.

The measurements were achieved thanks to the McGill team’s development of instrumentation that could be used by scientists in a variety of disciplines: to examine the fleeting but crucial transformations during chemical reactions, for example, or to enable biologists to obtain an atomic-level understanding of protein function. This ultrafast instrumentation combines tools and techniques of electron microscopy with those of laser spectroscopy in novel ways. 

“We’ve developed instruments and approaches that allow us to actually look into the microscopic structure of matter, on femtosecond time scales (one millionth of a billionth of a second) that are fundamental to processes in chemistry, materials science, condensed-matter physics, and biology,” says Bradley Siwick, the Canada Research Chair in Ultrafast Science at McGill.

“We’re able to both watch where nuclei go, and separate that from what’s happening with the electrons,” says Siwick, an associate professor in the departments of Chemistry and Physics. “And, on top of that, we are able to say what impact those structural changes have on the property of the material. That’s what’s really important technologically.”

By taking advantage of these recent advances, the research group has shed new light on a long-standing problem in condensed matter physics. The semiconductor-metal transition in Vanadium dioxide has intrigued the scientific community since the late 1950s.The material acts as a semiconductor at low temperatures but transforms to a highly conductive metal when temperature rises to around 60 degrees Celsius – not that much warmer than room temperature. This unusual quality gives the material the potential to be used in a range of applications, from high-speed optical switches to heat-sensitive smart coatings on windows.

The experiments took place in Siwick’s lab in the basement of McGill’s Chemistry building, where he and his team of grad students spent nearly four years painstakingly assembling a maze of lasers, amplifiers and lenses alongside an in-house designed and built electron microscope on a vibration-free steel table.

To conduct the experiments, the McGill team collaborated with the research group of Mohamed Chaker at INRS EMT, a university research centre outside Montreal. The INRS scientists provided the high quality, extremely thin samples of VO2 – about 70 nanometers, or 1000 times smaller than the width of a human hair– required to make ultrafast electron diffraction measurements.

The diffraction patterns provide atomic-length-scale snapshots of the material structure at specific moments during rearrangement. A series of such snapshots, run together, effectively creates a kind of movie, much like an old-fashioned flip book. 

 “This opens a whole new window on the microscopic world that we hope will answer many outstanding questions in materials and molecular physics, but also uncover at least as many surprises.  When you look with new eyes you have a chance to see things in new ways,” Siwick says.

The research was supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs program, and the Fonds du Recherche du Quèbec-Nature et Technologies.

``A photoinduced metal-like phase of monoclinic VO2 revealed by ultrafast electron diffraction``, Vance R. Morrison, Robert P. Chatelain et al, Science, Oct. 24, 2014.
DOI: 10.1126/science.1253779
http://www.sciencemag.org/content/346/6208/445.full 

Contact Information

Contact: Prof. Bradley Siwick
Organization: Departments of Physics and Chemistry

Secondary Contact Information

Contact: Chris Chipello
Organization: Media Relations Office
Office Phone: 514-398-4201

Chris Chipello | Eurek Alert!
Further information:
http://www.mcgill.ca/newsroom/channels/news/watching-hidden-life-materials-239767

Further reports about: Electrons INRS McGill VO2 dioxide experiments materials microscopic physics semiconductor snapshots structure

More articles from Materials Sciences:

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

nachricht New mechanical metamaterials can block symmetry of motion, findings suggest
14.02.2017 | University of Texas at Austin

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

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>