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Magnets

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CygnusRex

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First practical plastic magnets created

16:45 30 August 04

The world's first plastic magnet to work at room temperature has passed the elementary test of magnetism. Its creators at the University of Durham in the UK have used it to pick up iron filings from a laboratory bench.

In 2001, chemists from the University of Nebraska-Lincoln claimed to have created the world's first plastic magnet, but it only worked below 10 kelvin. Other researchers have made plastic magnets, but typically they only function at extremely low temperatures, or their magnetism at room temperature is too feeble to be of commercial use.

So the Durham team can claim to have made the first plastic magnet that could be used in everyday products. One of the most likely applications is in the magnetic coating of computer hard discs, which could lead to a new generation of high-capacity discs.

Jerry Torrance, a materials scientist based in California who is a consultant to some of the world's largest electronics and engineering companies, including IBM, describes the work as "a significant scientific breakthrough". However, he says that practical applications are probably still a long way off.

The new polymer was developed by Naveed Zaidi and his colleagues in Durham's organic electroactive materials group. The team created the new polymer from two compounds, emeraldine base polyaniline (PANi) and tetracyanoquinodimethane (TCNQ). They chose PANi because it is a metal-like electrical conductor that is stable in air. TCNQ was chosen because of its propensity to form charged particles called free radicals.

In conventional magnets, magnetism is the result of electron spins lining up. In their polymer, the researchers hoped to mimic this mechanism by creating an alignment of free radicals.

At first the new polymer showed little sign of magnetism, and after three months the researchers had reached the point where they felt that trying to induce magnetism in this polymer was a waste of time. "Just as we were about to give up and try a different approach, we decided to check the samples for a last time," says Sean Giblin.

It was a fortunate decision, because over the months the original polymer had developed magnetic properties. Further batches of the polymer confirmed its magnetism and ruled out the possibility that the magnetism had been caused by contamination. In addition, X-ray diffraction data showed an increase in the alignment of the polymer chains over three months, which probably accounts for the increase in magnetism.


Made to measure
Although the polymer's magnetism is weak compared with conventional metal magnets, the researchers are confident that they can improve it.

"The reaction is not yet 100 per cent efficient along the polymer and the strength of effect varies throughout the material. Once we increase this efficiency, this overall strength will certainly increase," says Zaidi.

The nature of polymer synthesis means that magnetic properties could effectively be made to measure, by varying the proportions of the initial chemicals. "This is only the beginning. From this initial polymer, much better systems can be synthesised in future," says Zaidi.

And in addition to computer hard discs, the team thinks that plastic magnets could have important medical applications, for example in dentistry or the transducers used in cochlear implants. Organic magnetic materials are less likely to be rejected by the body.
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Source
 
World-record magnet tested in Florida

TALLAHASSEE, Fla., Dec. 14 (UPI) -- The Tallahassee, Fla.-based National High Magnetic Field Laboratory is ending the year by completing development and testing of a world-record magnet.

The achievement -- said to be of international importance -- involves a 35-tesla magnet, the highest-field "resistive" magnet in the world. The state-of-the-art magnet, which incorporates "Florida-Bitter" technology invented at the lab, was designed and built on-site and is available for research.

The 35-tesla magnet is an upgrade of an existing 30-tesla magnet and it surpasses the previous record of 33 tesla also held by the laboratory.

"Tesla" is a measurement of the strength of a magnetic field; 1 tesla is equal to 20,000 times the Earth's magnetic field. Typical magnetic resonance imaging machines in hospitals provide fields in the range of 1 to 3 tesla.

The 35-tesla magnet will be primarily used for physics and materials science research, lab officials said.

The laboratory, funded by the National Science Foundation and the State of Florida, is operated by a consortium consisting of Florida State University, the University of Florida and Los Alamos National Laboratory.

Magnet
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Source: Florida State University
Date: 2005-12-14
URL:
http://www.sciencedaily.com/releases/20 ... 220120.htm

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Another World-record Achievement For National High Magnetic Field Laboratory
The National High Magnetic Field Laboratory is ending its year with another achievement of international importance as engineers and technicians this week completed testing of a world-record magnet.

With the completion of a new, 35-tesla magnet, the highest-field "resistive" magnet in the world is located at the Tallahassee facility. The state-of-the-art magnet, which incorporates "Florida-Bitter" technology invented at the lab, was designed and built on-site and is immediately available for research.

The 35-tesla magnet is an upgrade of an existing 30-tesla magnet and surpasses the previous record of 33 tesla, also held by the laboratory. "Tesla" is a measurement of the strength of a magnetic field; 1 tesla is equal to 20,000 times the Earth's magnetic field. Typical magnetic resonance imaging (MRI) machines in hospitals provide fields in the range of 1 to 3 tesla. Put another way, the increase from 30 to 35 teslas in the new magnet represents a 17-percent jump, or an increase equal to the magnetic force of two MRI machines.

"With the advances that magnet lab engineers and technicians have made in magnet technology, it would be easy to become nonchalant about the significance of these world records," said Gregory S. Boebinger, director of the facility. "But each increase in field represents world-class engineering and a quarter-of-a-million-dollar investment to provide new and unique opportunities for scientific discovery."

Mark D. Bird, project leader on the 35-tesla upgrade, said that as engineers learn more about existing materials and as new materials become available, the lab is able to upgrade its existing magnets.

"We continuously strive to improve the performance of our magnets both by pushing the fields higher and by increasing the quality of the fields," said Bird. "Our next new magnet will focus not just on high field, but uniform field as well."

And higher and more stable fields are what the lab's users, who come from all over the world, demand. The magnet lab is funded by the state of Florida and the National Science Foundation to provide the international research community with the highest magnetic fields possible to conduct research in all areas of science. Use of the magnets is free as long as researchers agree to share the results of their work.

The majority of the magnets and instrumentation used at the magnet lab are developed by laboratory staff and operated by in-house researchers who collaborate with the hundreds of scientists who visit each year. The 35-tesla magnet, which has a 32 mm, or 1.25-inch, experimental space, will be used primarily for physics and materials science research.

Magnetism is a critical component of many scientific discoveries and a surprising number of modern technologies, including computer memory and disk drives. High-field magnets now stand beside lasers and microscopes as essential research tools for probing the mysteries of nature. Long used by the physics community to understand the fundamental nature of matter and electronic structures, magnetic fields now are used by biologists, chemists and even pharmacists to better understand complex molecules and tissues, and in fact are responsible for the development of the MRI technology that has changed the face of modern medicine.



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Funded by the National Science Foundation and the State of Florida, The National High Magnetic Field Laboratory (www.magnet.fsu.edu) is operated by a consortium consisting of Florida State University, the University of Florida and Los Alamos National Laboratory.The Tallahassee facility houses both resistive -- so-called "powered" -- magnets that use both electricity and cooled water to operate and superconducting magnets that, once brought to full field, require little or no electrical power to run. In July, the lab commissioned a world-record, 900-megahertz, wide-bore nuclear magnetic resonance magnet, which is expected to yield important discoveries in the fields of chemical and biomedical research.
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