Powering Voyager – SiGe alloys

What doe it looks like?

Image of a SiGe alloy taken from here http://www.iue.tuwien.ac.at/phd/wittmann/node9.html

Image of a SiGe alloy taken from here http://www.iue.tuwien.ac.at/phd/wittmann/node9.html

What is it?

This material is pretty simple, from lots of standpoints – it’s only made from two elements (silicon and germanium) and forms the diamond structure.

Despite it’s simplicity, SiGe alloys (or sometimes known as ‘Siggie’) have had some pretty complex uses.  From being used to powder spacecrafts, to the being a massive technologicl leap for semiconductors.

It’s use in spacecrafts come from the fact that, when alloyed in the correct proportions, SiGe becomes a thermoelectric material.  This means that it can turn heat into electricity.   With the deep space probes, there’s just not enough sunlight to power these crafts with solar energy.  The solution has been to use radioisotopes (ofen of plutonium) to create heat, and then thermoelectric materials like SiGe to convert this into electricity to run the spacecraft.  The success of this is impressive, both Voyager 1 and 2 used SiGe alloys in their power generators and are still going to this day…

Where did the structure come from?
We couldn’t find SiGe in the Crystallography Open Database, so we’ve taken the image of the alloy’s crystal structure from here.  There’s lots more information on that site about how this material is made and the physics behind it.

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