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 Serendipity uncovers borophene's potential
23.02.2017 | Northwestern University

nachricht Switched-on DNA
20.02.2017 | Arizona State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

NASA eyes Pineapple Express soaking California

24.02.2017 | Earth Sciences

New gene for atrazine resistance identified in waterhemp

24.02.2017 | Agricultural and Forestry Science

New Mechanisms of Gene Inactivation may prevent Aging and Cancer

24.02.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>