What substance does not expand on heating?

Answer 1

For example pure silicon doesn't expand in a given range of temperature.

Also a mixture of amorphous and crystalline quartz has a thermal expansion coefficient near zero ("Zerodur" from Schott).

But the majority of materials suffer thermal expansion.

Answer 2

Within a certain limited temperature range, water does not expand on heating, but on cooling. That's why ice floats,

Answer 3

Between 0 and 4°C, water will contract when heated.