Nav: Home

New type of sensor material developed

March 28, 2017

Hokkaido University scientists have succeeded in developing a nickel complex that changes color and magnetism when exposed to methanol vapor. The new material can potentially be used not only as a chemical sensor, but also with future rewritable memory devices.

The phenomenon of color changes in a substance, triggered by volatile organic compound vapors or inorganic gas, is called vapochromism. Since its discovery at the end of the last century, scientists have focused their research on developing sensory materials that can visibly show the presence of harmful organic solvents. Furthermore, research on materials that synchronize color and other property changes, such as magnetism, could lead to broader applications.

The research team led by Masako Kato at Hokkaido University focused on developing materials that simultaneously change color and magnetism when exposed to vapors. To date, some iron complexes were known to switch magnetism between "paramagnetism" and "diamagnetism" at room temperature, but usually fall into stable states when temperatures are lower.

It was therefore important to develop materials that can change magnetism under a wider temperature range. The team focused on a nickel(II)-quinonoid complex. "As the complex changes magnetism when its coordination structure changes, we hypothesized that if solvent vapors could bind to nickel ions directly, the complex would simultaneously change colors and magnetism," says Masako Kato.

According to their research, a nickel(II)-quinonoid complex was placed in a high density methanol vapor environment. Once methanol molecules bonded with the complex, the coordination structure was transformed followed by a change in color from deep purple to orange. When exposed to vapors such as ethanol and chloroform, methanol molecules detached from the complex, reversing its color to deep purple.

In collaboration with Noriaki Matsunaga at Hokkaido University, they found that the color changes occurred along with changes in magnetism. When methanol molecules were removed from the complex, it switched from paramagnetism to diamagnetism, and both states could be maintained under a wide temperature range.

"This research marks the first time that vapor molecules have successfully changed magnetic states of nickel complexes," says Kato. "As the nickel complex reacts differentially to ethanol and methanol, it could be used in the future as a sensor material selective to methanol. We expect that further applications of this method may lead to novel materials that can record and erase data using vapor."

Hokkaido University

Related Magnetism Articles:

Stanford physicists discover new quantum trick for graphene: Magnetism
Physicists were stunned when two twisted sheets of graphene showed signs of superconductivity.
Utrafast magnetism: Electron-phonon interactions examined at BESSY II
How fast can a magnet switch its orientation and what are the microscopic mechanisms at play ?
Experimental physicists redefine ultrafast, coherent magnetism
For the first time ever, experimental physicists have been able to influence the magnetic moment of materials in sync with their electronic properties.
A new 2D magnet draws future devices closer
EPFL scientists have discovered a new type of 2D magnetic material that can be integrated into spintronic devices.
Magnetism discovered in the Earth's mantle
The well-known sources of the magnetic field that surrounds the Earth are the deep inside core and the Earth's crust.
First explanation for mechanism behind magnetism-driven NTE derived in 40 years
Most materials expand upon heating and contract upon cooling. Some behave inversely, a phenomenon known as negative thermal expansion (NTE).
Scientists discover new type of magnet
A team of scientists has discovered the first robust example of a new type of magnet -- one that holds promise for enhancing the performance of data storage technologies.
2D magnetism reaches a new milestone
Researchers at the IBS Center for Correlated Electron Systems, in collaboration with Sogang University and Seoul National University, reported the first experimental observation of a XY-type antiferromagnetic material, whose magnetic order becomes unstable when it is reduced to one-atom thickness.
Pressure tuned magnetism paves the way for novel electronic devices
Using very sensitive magnetic probes, an international team of researchers has found surprising evidence that magnetism which emerges at the interfaces between non-magnetic oxide thin layers can be easily tuned by exerting tiny mechanical forces.
Special topic: Superconductivity and magnetism in transition-metal compounds
SCIENCE CHINA Physics Mechanics Astronomy recently publishes a topical issue, in which eight articles are collected to touch some of the frontier studies of this field.
More Magnetism News and Magnetism Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.