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Question
What is the
magnetocaloric effect and what materials exhibit this effect
the most?
Asked by: Tim
Michnick
Answer
Some magnetic materials
heat up when they are placed in a magnetic field and cool down
when they are removed from a magnetic field. This is known as
the magnetocaloric effect.
This effect was discovered
by E. Warburg in 1881 in pure iron. The size of the effect has
been around .5 to 2°C per Tesla change in magnetic field. One
Tesla is about 20,000 times the earth's magnetic field.
Recently, alloys of gadolinium, germanium and silicon
have produces a much larger effect size of 3 to 4°C per Tesla
change. The general equation for this material is;
Gd_5(Si_xGe_1-x)_4, where x=0.5.
Experimental
refrigerators based on the magnetocaloric effect have been
tested in laboratories using magnetic fields of around 5T
produced by superconducting magnets. http://www.cfs.me.uvic.ca/PAGES/amr.html
Answered by: Scott
Wilber, President, ComScire - Quantum World Corporation
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