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 Water without windows: Capturing water vapor inside an electron microscope
13.12.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University

nachricht Columbia engineers create artificial graphene in a nanofabricated semiconductor structure
13.12.2017 | Columbia University School of Engineering and Applied Science

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>