what are some materials that expand as they cool?

Question

and what are there uses

Answer 1

linifer74,

Although they are rare compared to other materials, there are a few materials that expand upon cooling. Water expands upon turning to ice, but this is only applicable to the phase change... liquid water will expand when heated (not when cooled).

Cubic zirconium tungstate (ZrW2O8) is a widely studied material that expands upon cooling over a wide temperature range. There are other metal tungstates and vanadates that have been studied as well. In addition, there is a naturally occuring mineral, beta-eucryptite, that expands slightly upon cooling. My academic advisor and his former grad student actually did some of the pioneering work on the thermal properties of this mineral.

These materials are being developed for use in engineering applications... for example, components for building bridges and buildings that will not expand and cause structural damage on hot summer days. They're also used in electronics applications, so that when electrical components get hot they do not change size and end up touching other components and shorting out. They're also being investigated for use in dental fillings, so that when you drink your coffee in the morning your filling doesn't expand and crack your tooth.

Hope this helps!

Answer 2

Fluorocarbons, used in air conditioners. Air conditioners expand these gases to lower their temperature. Then the machines compress the fluorocarbon gases to high pressure and "ordinary" temperature. The gases give off heat to the yard outside the house.

Years ago, people used sulfur dioxide and ammonia in refrigerators. They also expand as they cool.

Answer 3

first of all, gas cools down and liquify. liquid can never have bigger volume than gas.

so, it is specifically about solid and liquid. if something expands after cooling, the density of solid is lower than in liquid form.

water is the best and most common example. that's why when you have cold drinks, you see ice floats. otherwise, when ice melts, your drink will overflow.

Answer 4

Water. It starts to freeze at a temperature bellow 0 C.

Answer 5

Water, below 4 degrees

Answer 6

Gallium metal expands when it solidifies