Most materials swell when they warm, and shrink when they cool. A University of Connecticut physicist, however, has been investigating a substance that responds in reverse. Scandium trifluoride, a material with negative thermal expansion, may be used to create more durable electronics.
Scandium trifluoride drastically shrinks as it is heated, even to temperatures as high as 1,100K or 2,000 F. The material also keeps its same, stable cubic crystal structure over an even larger temperature range, from near absolute zero to 1,800 degrees Kelvin (2,780 degrees Fahrenheit), at which point it melts.
To investigate scandium trifluoride, the researchers used x-rays to reveal how the crystal's atoms moved at very low temperatures, close to absolute zero.
The researchers knew exactly how much energy the x-rays had going in to the crystal, and they carefully tracked how much energy the x-rays had coming out. By tracking the amount of lost energy that the x-rays lost, the angle that they entered the crystal, and the angle that they emerged, the researchers calculated how the scandium trifluoride atoms moved.
The material's transparent crystal structure could be used as a component of devices that do not shrink, crack, or break under thermal stress.