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Which materials or compounds expand in response to cold temperatures? This material or compound should expand at a slow (but constant rate), from about 0–20 months when in the following temperature range −25 °C to −10 °C. Also, the compound should not react with plastic or be toxic to humans or environment.

Please explain why the compound does this as well.

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This seems to me to be a chemistry question. I found one compound pubs.acs.org/doi/abs/10.1021/ja106711v , Cubic ScF3 from the references in the wiki article en.wikipedia.org/wiki/… –  anna v Nov 13 '12 at 20:49
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Isn't the typical example is water and ice? –  m0nhawk Dec 16 '12 at 8:55

2 Answers 2

In old time printing using type, the alloy used for the type was designed to have a zero coefficient of thermal expansion over a wide range so that they type did not change shape when cast at a high temperature and then cooled off.

It is very likely that slight modifications of that formula would yield an alloy with either a positive or negative thermal coefficient.

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Perhaps one of the most studied materials to exhibit negative thermal expansion is Cubic Zirconium Tungstate (ZrW2O8).

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