Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A simple magnet can control the color of a liquid, making new technologies possible

04.07.2007
Research by UC Riverside's Yadong Yin and colleagues will be featured on the inside cover of Angewandte Chemie, a top science journal

University of California, Riverside nanotechnologists have succeeded in controlling the color of very small particles of iron oxide suspended in water simply by applying an external magnetic field to the solution. The discovery has potential to greatly improve the quality and size of electronic display screens and to enable the manufacture of products such as erasable and rewritable electronic paper and ink that can change color electromagnetically.

In their experiments, the researchers found that by changing the strength of the magnetic field they were able to change the color of the iron oxide solution – similar to adjusting the color of a television screen image.

When the strength of the magnetic field is changed, it alters the arrangement of the spherical iron oxide particles in solution, thereby modifying how light falling on the particles passes through or is deflected by the solution.

Study results appear in Angewandte Chemie International Edition’s online edition today. The research paper is scheduled to appear in print in issue 34 of the journal. Identified by Angewandte Chemie as a “very important paper,” the research will be featured on the inside cover of the print issue.

“The key is to design the structure of iron oxide nanoparticles through chemical synthesis so that these nanoparticles self-assemble into three-dimensionally ordered colloidal crystals in a magnetic field,” said Yadong Yin, an assistant professor of chemistry who led the research.

A nanoparticle is a microscopic particle whose size is measured in nanometers, a nanometer being a billionth of a meter. (A pin head is 1 million nanometers wide.)

A colloid is a substance comprised of small particles uniformly distributed in another substance. Milk, paint and blood are examples of colloids.

“By reflecting light, these crystals – also called photonic crystals – show brilliant colors,” Yin said. “Ours is the first report of a photonic crystal that is fully tunable in the visible range of the electromagnetic spectrum, from violet light to red light.”

A photonic crystal controls the flow of light (photons) and works like a semiconductor for light. The nanoparticles’ spacing dictates the wavelength of light that a photonic crystal reflects.

Iron oxide (formula: Fe3O4) nanoparticles are “superparamagnetic,” meaning that they turn magnetic only in the presence of an external magnetic field. In contrast, “ferromagnetic” materials become magnetized in a magnetic field and retain their magnetism when the field is removed.

The researchers used the superparamagnetic property of iron oxide particles to tune the spacing between nanoparticles, and therefore the wavelength of the light reflection – or the color of the colloidal crystals – by changing the strength of the external magnetic field.

“Other reported photonic crystals can only reflect light with a fixed wavelength,” Yin said. “Our crystals, on the other hand, show a rapid, wide and fully reversible optical response to the external magnetic field.”

Photonic materials such as those used by Yin and his team could help in the fabrication of new optical microelectromechanical systems and reflective color display units. They also have applications in telecommunication (fiber optics), sensors and lasers.

“This is an elegant method that allows researchers in the field to assemble photonic crystals and control their spacing by using a magnetic field,” said Orlin Velev, an associate professor of chemical and biomolecular engineering at North Carolina State University, Raleigh, N.C., who was not involved in the research. “A simple magnet can be used to change the color of a suspension throughout the whole visible spectra. This has potential to result in usable precursors for various photonic devices.”

“What should make the technology commercially attractive is that iron oxide is cheap, non-toxic and available in plenty,” Yin said.

Yin explained that the new technology can be used to make an inexpensive color display by forming millions of small pixels using the photonic crystals. “A different color for each pixel can be assigned using a magnetic field,” he said. “The advantage is that you need just one material – for example, photonic crystals like iron oxide – for all the pixels. Moreover, you don’t need to generate light in each pixel. You would be using reflected light to create the images – a form of recycling.”

Iqbal Pittalwala | EurekAlert!
Further information:
http://www.ucr.edu

Further reports about: Iron Magnetic Nanometer Oxide Photonic Yin magnetic field nanoparticle photonic crystals reflect

More articles from Life Sciences:

nachricht In focus: Peptides, the “little brothers and sisters” of proteins
12.11.2018 | Technische Universität Berlin

nachricht How to produce fluorescent nanoparticles for medical applications in a nuclear reactor
09.11.2018 | Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

Im Focus: Nanorobots propel through the eye

Scientists developed specially coated nanometer-sized vehicles that can be actively moved through dense tissue like the vitreous of the eye. So far, the transport of nano-vehicles has only been demonstrated in model systems or biological fluids, but not in real tissue. The work was published in the journal Science Advances and constitutes one step further towards nanorobots becoming minimally-invasive tools for precisely delivering medicine to where it is needed.

Researchers of the “Micro, Nano and Molecular Systems” Lab at the Max Planck Institute for Intelligent Systems in Stuttgart, together with an international...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

In focus: Peptides, the “little brothers and sisters” of proteins

12.11.2018 | Life Sciences

Materials scientist creates fabric alternative to batteries for wearable devices

12.11.2018 | Materials Sciences

A two-atom quantum duet

12.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>