Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Strengthening thin-film bonds with ultrafast data collection

23.10.2014

When studying extremely fast reactions in ultrathin materials, two measurements are better than one. A new research tool invented by researchers at Lawrence Livermore National Laboratory (LLNL), Johns Hopkins University and the National Institute of Standards and Technology (NIST) captures information about both temperature and crystal structure during extremely fast reactions in thin-film materials.*

The combined device will help scientists study new materials and processes used to make advanced technologies, including state-of-the-art semiconductors and flat-screen display devices, says David LaVan, a NIST materials scientist who co-led the study.


Temperature and structure: Graph shows heat absorbed by a thin film of aluminum as its temperature increased. Inset boxes show electron diffraction patterns captured by DTEM as temperature changes. The patterns reveal the crystal structure and orientation of the aluminum. At low temperatures, pattern is characteristic of a face-centered-cubic crystal structure. When the sample is heated past the large melting peak, the spots disappear indicating that the aluminum has lost its crystal structure due to melting.

Credit: NIST

Modern electronics manufacturing often pushes the limits of current measurement technology. Making a flat-screen display requires bonding a large sheet of a pure, rare material to an underlying metal substrate with as few defects as possible. To do so, manufacturers typically sandwich a thin film between the two materials and heat it rapidly to high temperatures, causing it to react and bond the metals.

This method usually works, but industry researchers would like to optimize the process. And existing tools to describe what's happening in the reactive thin film provide only incomplete information. One such technique, nanocalorimetry, can track very precisely large temperature changes—at rates up to ,1000 degrees Celsius per millisecond—that occur at a very small scale.

Such a measurement can alert researchers to a material's phase transitions, for example, when a metal melts. But nanocalorimetry tells researchers little about the actual chemical processes or microstructural changes they are measuring as a material heats up or cools down.

To study these changes, LaVan's LLNL collaborators Geoffrey Campbell, Thomas LaGrange and Bryan Reed developed a different device, the dynamic transmission electron microscope (DTEM). In traditional transmission electron microscopy, diffraction and transmission patterns made by electrons passing through a thin sample provide information about how the sample's atoms are arranged. But TEM typically requires that the sample maintain one crystal structure for an extended period, as the microscope's detector captures enough electrons to generate an image.

DTEM, by contrast, captures structural information very rapidly. It relies on a pulsed laser to send short, bright blasts of electrons through a sample. LaVan and his colleagues at NIST and Johns Hopkins realized that if the LLNL group's DTEM laser pulses were synched with a rapid temperature rise, the researchers could simultaneously track phase transitions and structural changes in materials they were studying. "It's like peanut butter and chocolate," LaVan says. "If we can somehow get these two instruments working simultaneously, we'll have the whole story."

But first the researchers needed to shrink the circuitry for their nanocalorimeter to a tenth of its original size, so that it could fit inside the microscope. The researchers also needed to write new software to synchronize the microscope's electron pulses with the nanocalorimeter's rapid heating pulses. "To get [the devices] to work together was really a substantial effort from three different research groups," LaVan says.

Finally, LaVan and team member Michael Grapes, a research associate at NIST, and graduate student in materials science Timothy Weihs' group at Johns Hopkins, flew the redesigned nanocalorimeter to Livermore, synchronized it with the DTEM, and ran tests on thin films of materials such as aluminum, whose microstructural and thermal properties are well understood. The scientists found that, as expected, the nanocalorimeter recorded phase transitions at the same time the DTEM recorded structural changes, and both sets of measurements were consistent with their study materials' known properties.

The research team is already moving on to study other, less well-understood materials. Recently, the scientists have used their combined nanocalorimeter-DTEM to measure what happens when aluminum and nickel combine to form thin-film alloys. The team's study provides, for the first time, simultaneous structural and thermal data on this reaction at high heating rates, LaVan says.

###

* M.D. Grapes, T. LaGrange, L.H. Friedman, B.W. Reed, G.H. Campbell ,T.P. Weihs and D.A. LaVan. Combining nanocalorimetry and dynamic transmission electron microscopy for in situ characterization of materials processes under rapid heating and cooling. Review of Scientific Instruments 85, 084902. Published online Aug. 18, 2014.

Michael Baum | Eurek Alert!

More articles from Materials Sciences:

nachricht Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University

nachricht Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

The Maturation Pattern of the Hippocampus Drives Human Memory Deve

23.07.2018 | Science Education

FAU researchers identify Parkinson's disease as a possible autoimmune disease

23.07.2018 | Health and Medicine

O2 stable hydrogenases for applications

23.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>