A CSIC team has obtained a method for replacing in the cryocoolers the exchangers based on rare earths, which are very expensive and scarce. They propose to use other materials, which are porous and cheaper.

One of the rare earths used for cryocoolers: pure amorphous Gadolinium, about 12 grams. Image: Wikimedia Commons. Autor: JuriiCryocoolers, equipments to get very cold temperatures (below 15 Kelvin, which is equivalent to 258.15 C below zero) have gained relevance in the last twenty years. They are an essential research tool when it is necessary to work at liquid helium temperatures. Also, in hospitals, the magnetic resonance equipments work with superconducting magnets that require cooling at these very low temperatures.

Almost all cryocoolers are based on the cyclic compression and expansion of helium gas. These refrigerators need heat exchangers or regenerators, which act on the cold/hot cycle of the gas. Nowadays, regenerators for getting helium liquid temperatures are particles made on alloys of rare earths (gadolinium holmium y erbium).

The production of these rare earths is concentrated in China, which progressively restricts their exportation and therefore raises their prices. In the case of conventional cryocoolers, regenerators based on rare earths suppose approximately a fifth part of the whole equipment price (between 20,000 an 40,000 Euros). Whatever the case, it means thousands of Euros, as it is necessary to renew the regenerators every two years.

Cryocooler in a lab. CSIC.CSIC scientists Marco Evangelisti, Olivier Roubeau and Fernando Luis, at the Instituto de Ciencia de Materiales de Aragón en Zaragoza, and Daniel Ruiz-Molina, at the Centro de Investigación en Nanociencia y Nanotecnología, in Barcelona, have patented a method that enables the replacement of rare earths with porous materials which are already available on the market. The new materials would have similar performance to the current regenerators; they would be much lighter, due to its porosity, and between 50 and 100 times cheaper.

As Marco Evangelisti explains, the patent covers the methodology for processing the materials “in order to obtain particles with the proper size, shape and porosity”. A great advantage is that it will be possible to use the new regenerators in the conventional cryocoolers that now are using rare earths, making unnecessary any technical change in the equipment.

More information:

About cryocoolers

About international market of rare earths

Contact:

Dania Todorova Marinova
Vicepresidencia de Transferencia de Conocimiento, CSIC
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.