Are there any ma­te­ri­als that don’t ex­pand when heated?

BBC Earth (Asia) - - Q & A - RM

Poly­mers like rub­ber shrink on heat­ing as their molec­u­lar chains curl up, and wa­ter shrinks when warmed from its freez­ing point to around 4°C. After that, though, it be­haves nor­mally, and ex­pands on warm­ing. In con­trast, so-called neg­a­tive ther­mal ex­pan­sion (NTE) ma­te­ri­als never be­have them­selves. Dis­cov­ered in 1959, they in­clude zir­co­nium tungstate, whose bizarre crys­tal struc­ture means that it keeps shrink­ing as it’s warmed from any tem­per­a­ture above ab­so­lute zero (-273°C) to over 770°C.

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