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Name: Jim
Status: educator
Grade: 9-12
Location: IL
Country: USA
Date: N/A


Question:
What materials can be magnetized as temperature is reduced low enough? For example, is it possible to magnetize zinc at a low enough temperature?


Replies:
Hi Jim,

To answer your specific question, zinc cannot be magnetized at any temperature. The term "Curie Temperature" is the temperature above which a magnetic material looses its magnetic properties, or conversely, below which it has magnetic properties. There are no common metals that have a curie temperature below about room temperature, and only one (Gadolinium) whose curie temperature is that low; it becomes magnetic below 293°K (20°C), that is, at room temperature and below. All other metals and alloys that exhibit magnetic properties have curie temperatures much higher, usually at least a few hundred degrees Celsius. There are no metals or alloys that have Curie temperatures (that is, that can me made magnetic) by cooling them below room temperature. In fact, other than Gadolinium, the only metals exhibiting any magnetic properties are a few members of the 4th period of the periodic table, for example, Iron or Nickel.

Regards,

Bob Wilson


Materials that are magnetic require lined up unpaired electrons in one form or another. Some materials (called ferromagnets) have electrons unpaired at room temperature. Other materials (called paramagnets) have electrons that are randomly organized, say at room temperature, but that become organized if the temperature is reduced so that the atoms are not bounced around too much. Other materials, like zinc, do not have any electrons that can become unpaired, so they do not become magnetic at any temperature. These are called diamagnetic. Sometimes these transitions between paired and unpaired orientations of electrons are reversible, but in other cases they are not. So for example some forms of magnetic iron lose their magnetism if they are heated and cooled.

Vince Calder

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