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New type of material that heat can't bloat

Most substances expand when warmed. That can be bad, especially in devices such as precision telescopes, whose components must maintain their shapes across a wide temperature range. Now, scientists have discovered a metallic compound that nixes thermal expansion by what appears to be an unprecedented mechanism.

Mercouri G. Kanatzidis and his colleagues at Michigan State University in East Lansing created the compound by heating a mixture of equal parts of ytterbium, gallium, and germanium to 850C and then cooling the melt to room temperature.

The resulting silvery metal neither enlarges nor shrinks over the broad range of about –200C to room temperature, the scientists report in the Oct. 16 Nature.

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