2003-03-29

dysprosium

HINT: It is not "a poisonous substance causing an inability to write".

One of the elements (Symbol Dy; atomic number 66; atomic weight 162.5).

The name of this element derives from the Greek for "hard to get".

Dysprosium has one of the highest magnetic strengths among the elements, and is used in alloys for the best kinds of permanent magnets [Nature's Building Blocks, John Emsley, p. 130]. Other uses include neutron absorption in nuclear reactors, intense halide discharge lights, radioactivity dosimeters, specialty capacitors and in erasable optical laser-read discs.

Finally, one dysprosium alloy, Terfenol, visibly lengthens and shortens when exposed to a magnetic field (applications are an active area of research).

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