Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tunable Materials Clear the Way for Advanced Optics

14.01.2016

A team of German and American physicists develops a way to precisely engineer the transition point for the phase-transition material vanadium dioxide to occur at specific temperatures.

Now you see it, now you don’t: In books and movies, wizards use magic spells to easily change things from a solid to see-through state. However, in reality, materials with properties called phase transition can pull off a similar trick, changing from clear to cloudy depending on the temperature or an applied electric field.


The physicist Jura Rensberg from the University of Jena (Germany) is part of the international researcher team.

Photo: Jan-Peter Kasper/FSU

Recently, a multi-institutional international team of researchers with the participation of physicists from the Friedrich Schiller University Jena (Germany) developed a way to engineer the transition point for the phase-transition material vanadium dioxide to occur at specific temperatures.

The research, published today in Nano Letters, could lead to new types of tunable materials for optics and thermal regulation.

“Essentially, any optical component would be better if it were tunable,” says Mikhail Kats, a University of Wisonsin-Madison (USA) assistant professor of electrical and computer engineering and senior author of the paper.

Rather than relying on mechanical components to focus an object such as a camera lens or telescope eyepiece, a tunable material changes its innate optical properties on demand. Scientists have known for more than 50 years that substances like vanadium dioxide can transition between opaque and transparent. However, these materials typically switch under only one particular set of conditions, limiting their applicability.

“In most phase-transition materials, the change occurs at conditions that are far from room temperature, and thus are difficult to incorporate into useful devices,” says Kats.

The researchers not only changed vanadium dioxide’s intrinsic shift point from 68 degrees Celsius to below room temperature, they also successfully tuned the transition for that material to any temperature. “This finding is going to open new frontiers in photonic devices,” says Shriram Ramanathan, a professor of materials engineering at Purdue University in West Lafayette, Indiana (USA), who also contributed to the research.

Use in “smart” walls possible

Because optical and physical properties arise from the same underlying physical principles, vanadium dioxide’s thermal and electrical conductivities also shift with the transition. These types of materials could be used, for example, in homes as “smart” walls or windows that respond to the environment.

“Objects designed to emit light efficiently at high temperatures but not at low temperatures could be used as purely passive temperature regulators that do not require external circuitry or power sources,” Kats says.

Previously, researchers attempting to change the transition temperatures of vanadium dioxide always introduced impurities as they created it. However, this method uniformly alters the material’s entire surface – so instead, the German-American team of researchers bombarded specific regions of the vanadium dioxide with energetic ions.

Ion irradiation creates defects in materials, usually an unintended side effect. However, collaborator Carsten Ronning of the Friedrich Schiller University Jena, Germany, explains, the researchers’ advance now capitalizes on those defects. “The beauty in our approach is that we take advantage of the ‘unwanted’ defects,” he says. Directing the ion-beam at specific regions of a surface allowed the researchers to make nanoscale modifications to the material.

“We can precisely control the transition temperature everywhere on the sample, with roughly 20-nanometre precision,” Ronning states. “We have been able to use this method to create highly effective meta-surface areas which have multiple phase transitions at the same time.” This technique enabled the researchers to design and create a novel optical polariser that changes selectivity based on temperature.

Scientists spanning the globe contributed to this research. The manuscript’s co-first authors, Jura Rensberg of the Friedrich Schiller University Jena and Shuyan Zhang of Harvard University, are pursuing PhDs in Professor Carsten Ronning’s and Professor Federico Capasso’s laboratories, respectively.

Original publication:
Nano Letters (2016), Article ASAP, DOI: 10.1021/acs.nanolett.5b04122
http://pubs.acs.org/toc/nalefd/0/0

Contact person (in Jena):
Prof. Dr. Carsten Ronning
Institute for Solid State Physics of the Friedrich Schiller University Jena
Helmholtzweg 3
07743 Jena, Germany
Phone: +49 (0)3641 / 947300
Email: carsten.ronning[at]uni-jena.de

www.nano.uni-jena.de

Weitere Informationen:

http://www.uni-jena.de/en/start.html

Axel Burchardt | idw - Informationsdienst Wissenschaft

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

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....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

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

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>