Greetings.

Has anyone here already; or what would it take to put together a rustic, magnetocaloric refrigerator using gadolinium, even if by manual cranking ?

Gadolinium exposed to a magnetic field warms up; while In that state; does reversing the magnetic polarity changes anything, or removal of the field is needed ?

Moving Gd into a magnetic field takes kinetic energy ? Removing it from a magnetic field also uses kinetic energy ?

On 4/22/2025 at 8:27 PM, Externet said:

Greetings.

Has anyone here already; or what would it take to put together a rustic, magnetocaloric refrigerator using gadolinium, even if by manual cranking ?

Gadolinium exposed to a magnetic field warms up; while In that state; does reversing the magnetic polarity changes anything, or removal of the field is needed ?

Moving Gd into a magnetic field takes kinetic energy ? Removing it from a magnetic field also uses kinetic energy ?

I was not previously aware of the magnetocaloric effect so thanks for drawing it to my attention. From the little I have (rather quickly and superficially) read up on this, it looks to me as if the warming up is due, not to kinetic energy added by moving the specimen into or out of the field, but to a change in its effective specific heat capacity. When the magnetic domains line up in the field it seems as if there is a reduction in the degrees of freedom of the atoms, reducing the heat capacity and so the temperature rises even though no heat has been added.

But I'll defer to a physicist on this, obviously. 🙂

I know there’s an effect called magnetostriction, which is the physical expansion/contraction of domains as you cycle the magnetic field; I think it’s responsible for the humming of transformers.

My only exposure to magnetic refrigeration was in the context of discussion of cryogenic cooling, done by someone on my thesis committee, in contrast to the then-new concept of laser cooling that was used in my research. That was limited to small amounts of heat flow to get you fairly cold (tenths of a Kelvin?) but you still had to remove energy via other means, and had to start pretty cold (e.g. liquid nitrogen and then helium, IIRC)

Thank you.

Been sporadically following if there was advances during the last ~10 years somewhere else since ojose.com and scirus.com went belly up. The simplistic first rotary drawing that cannot find now was very convincing of having a good potential; gadolinium exposed to magnetism, then moved to a place to dissipate the heat and later moved to a place without the magnetic field to absorb heat.

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Just links ---> https://refindustry.com/articles/techguides/magnetic-refrigeration-revolutionizing-cooling-technology-with-the-magnetocaloric-effect/

https://refindustry.com/articles/articles/magnetic-cooling/

https://www.machinedesign.com/markets/energy/article/21833679/magnetic-refrigeration-heats-uphttps://undecidedmf.com/how-magnetic-cooling-is-breaking-all-the-rules/

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