- PARIS (AFP) - An exotic metal
compound could be the answer to a major problem facing spaceship designers
-- materials that expand or contract with the temperature, a phenomenon
with the potential to inflict dangerous stress.
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- The mixture of ytterbium, gallium and germanium neither
expands nor contracts on heating, and also conducts electricity, according
to a study published in Nature, the British science weekly.
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- The study, led by Mercouri Kanatzidis of Michigan State
University, theorizes that as the material warms, electrons move from the
ytterbium atoms to gallium atoms.
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- In doing so, the ytterbium atoms shrink, making up for
an increase in the size of gallium atoms.
-
- Thermal expansion and contraction are a headache for
spaceships because they can inflict tiny holes in a metal that can enlarge
with the buffeting of re-entry and potentially widen to become mortal cracks.
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