The discovery was only made recently

Aug 2, 2010 12:48 GMT  ·  By

Investigators from the Massachusetts Institute of Technology (MIT) have recently discovered that the widely-used chemical element silicon is capable of exhibiting the property known as “retrograde melting.” Substances capable of that basically melt as temperatures decrease, opposite than the behavior “normal” chemicals exhibit. When mixed up with high concentrations of specific metals, silicon too can melt as it cools, the MIT group says, quoted by PhysOrg.

Silicon is one of the most common materials today, given that the entire electronics industry is built on it. Processors and circuits would be impossible without their silicon substrates, and so numerous studies have been conducted on the element. None of them were however able to determine that silicon can exhibit retrograde melting until now. The MIT researchers focused their attention on a compound containing silicon, copper, nickel and silicon. This mix was capable of melting once it reached temperatures lower than 900 degrees Celsius.

Generally, silicon melts – as in turns from solid to mixture of liquid and solid – at around 1414 degrees Celsius. By using the new mix as a target, the science team was able to observe the sample using a specialized X-ray fluorescence microprobe technology. They conducted the investigation inside a special type of particle accelerator called a synchrotron, which was capable of generating the necessary conditions for the research. The results are detailed in the latest issue of the esteemed scientific journal Advanced Materials.

“If you can create little liquid droplets inside a block of silicon, they serve like little vacuum cleaners to suck up impurities,” says the senior author of the paper, Tonio Buonassisi, who was also the leader of the MIT team. He is also the SMA assistant professor of mechanical engineering and manufacturing at the Institute. The scientist explains that the new discoveries could be used to produce a host of innovations that could lower production costs associated with creating certain silicon-based electronics.

“Now that we know liquid inclusions can form, the question is, how efficient as sinks for impurities are they? How stable are they? Can they keep the impurities localized during other process steps – for example, during the final firing process of a solar cell?” concludes senior research scientist Matthias Heuer, who is based at the solar-energy startup company Calisolar.