Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chameleon for Optoelectronics

13.07.2007
Optical semiconductors made of magnetic particles change their color depending on magnetic field strength

A liquid that changes its color “on demand” and can take on any color of the rainbow one desires? A research team headed by Yadong Yin at the University of California, Riverside (USA) has now shared the secret of their wonderful liquid with the journal Angewandte Chemie: Nanoscopic particles made of tiny magnetic crystals coated with a plastic shell self-assemble in solution to form photonic crystals—semiconductors for light. When a magnetic field is applied, the optical properties of the crystals change, allowing their color to be very precisely adjusted through variation of the strength of the field.

The crystals involved here are no “conventional” lattices of ions or molecules like the one we are familiar with for salt; instead they are colloidal crystals, periodic structures that form from uniform solid particles that are finely dispersed in a liquid. Colloidal crystals can be produced at little cost and on a large scale—and can be used as photonic crystals. Photonic crystals are the optical analogue of electronic semiconductor materials. Like their electronic counterparts, they have photonic band gaps, forbidden energy levels, or wavelengths, at which the photonic crystal does not transmit light. These optical properties depend on the spatial relationships within the crystal.

Current research is concerned with photonic crystals whose forbidden bands are variable and can be adjusted quickly and precisely in response to an external stimulus. These requirements have been impossible to meet until now.

... more about:
»Cluster »Magnetic »Photonic »photonic crystals

One stimulus that could be used is a magnetic field, if the crystals are made of magnetic materials, such as iron oxide. The problem with this is that the magnetization is maintained when the particles grow into larger domains (ferromagnetism). Yin and his team have found a solution: They coated nanoscopic iron oxide particles with a plastic called polyacrylate. This results in separate clusters of nanocrystals, which self-assemble in solution to form colloidal photonic crystals. The forces of the magnetic field affect every individual cluster, changing the cluster-to-cluster distances within the crystal lattice. Depending on the distance from the magnet and thus the field strength, the color of the colloidal crystal changes right across the whole visible spectrum. This response is rapid and fully reversible because the nanocrystals in clusters are so small that they lose their magnetism when the magnetic field is shut off (superparamagnetism). Potential applications for these switchable “optical semiconductors” include novel optoelectronic components for telecommunications, displays, and sensors.

Author: Yadong Yin, University of California, Riverside (USA), http://www.chem.ucr.edu/index.html?main=faculty&facsort=profile&faculty=yin

Title: Highly Tunable Superparamagnetic Colloidal Photonic Crystals

Angewandte Chemie International Edition, doi: 10.1002/anie.200701992

Yadong Yin | Angewandte Chemie
Further information:
http://pressroom.angewandte.org

Further reports about: Cluster Magnetic Photonic photonic crystals

More articles from Life Sciences:

nachricht Scientists enlist engineered protein to battle the MERS virus
22.05.2017 | University of Toronto

nachricht Insight into enzyme's 3-D structure could cut biofuel costs
19.05.2017 | DOE/Los Alamos National Laboratory

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>