Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Materials: Cubic cluster chills out

28.08.2014

A gadolinium-based material that can be cooled by varying a magnetic field may be useful for cooling low-temperature sensors.

Magnetic refrigeration is attracting attention as an efficient way to chill sensitive scientific instruments. This refrigeration method exploits the magnetocaloric effect, in which an external magnetic field controls the temperature of a magnetic material.


The magnetic refrigerant contains a cubic structure made of two gadolinium ions (pink), two nickel ions (green) and four oxygen atoms (red), surrounded by 2-(hydroxymethyl)pyridine molecules.

Copyright : 2014 A*STAR Institute of Materials Research and Engineering

Effective magnetic refrigerants are often difficult to prepare, but now Andy Hor of the A*STAR Institute of Materials Research and Engineering and the National University of Singapore and his colleagues have created a powerful magnetic refrigerant that is easy to make in the lab [1].

Compounds with a large magnetocaloric effect typically contain atoms with many unpaired electrons, each of which generates its own tiny magnetic moment. During magnetic refrigeration, an external magnetic field forces these atomic magnetic moments to line up in the same direction. As the magnetism of the atoms becomes more ordered (which reduces the entropy of the system), the material’s temperature rises.

Once the heat has been removed by a flowing liquid or gas, the external magnetic field is reduced. This allows the atomic magnetic moments to become disordered again, cooling the material so that it can be used to draw heat from an instrument, before repeating the cycle.

Magnetic refrigerants commonly use the gadolinium(III) ion (Gd3+), because it has seven unpaired electrons. Most gadolinium complexes are made under harsh conditions or take a very long time to form, which limits their wider application. In contrast, the magnetic refrigerant developed by Hor and colleagues is remarkably easy to make.

The researchers simply mixed gadolinium acetate, nickel acetate and an organic molecule called 2-(hydroxymethyl)pyridine in an organic solvent at room temperature. After 12 hours, these chemicals had assembled themselves into an aggregate containing a cube-like structure of atoms at its heart (see image).

The team measured how an external magnetic field affected this ‘cubane’ material as the temperature dropped. Below about 50 K, they found that the material’s magnetization increased sharply, suggesting that it could be an effective magnetic refrigerant below this temperature.

The scientists then tested the effects of varying the external magnetic field at very low temperatures. They found that at 4.5 K, a large external field caused an entropy change that was close to the theoretical maximum for the system — and larger than most other magnetic refrigerants under similar conditions.

According to the team, the magnetocaloric effect of magnetic refrigerants has typically been enhanced by creating ever-larger clusters of metal atoms. In contrast, their cubane shows that much simpler aggregates, prepared under straightforward conditions, are promising as magnetic refrigerants.

Reference

1. Wang, P., Shannigrahi, S., Yakovlev, N. L., and Hor, T. S. A. Facile self-assembly of intermetallic [Ni2Gd2] cubane aggregate for magnetic refrigeration. Chemistry – An Asian Journal 8, 2943–2946 (2013).

Lee Swee Heng | Research SEA News
Further information:
http://www.research.a-star.edu.sg/research/7020
http://www.researchsea.com

Further reports about: A*STAR Magnetic Science aggregate chills electrons magnetism temperature tiny

More articles from Materials Sciences:

nachricht First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D
30.09.2016 | Oak Ridge National Laboratory

nachricht New Multiferroic Materials from Building Blocks
29.09.2016 | National Institute for Materials Science

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.

Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Paper – Panacea Green Infrastructure?

30.09.2016 | Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

 
Latest News

First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

30.09.2016 | Materials Sciences

New Technique for Finding Weakness in Earth’s Crust

30.09.2016 | Earth Sciences

Cells migrate collectively by intermittent bursts of activity

30.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>