Zirconium tungstate

By Neil Withers2016-03-11T00:00:00

Source: © Spute via Wikicommons (CC BY-SA 3.0)

Neil Withers investigates a compound with some unusual and unexpected behaviour

When you heat things up, they generally get bigger. That’s what I learnt at school, and for most things it holds true. But not all. There are some materials that actually shrink as they get hotter, and zirconium tungstate, ZrW₂O₈, is one of the most studied and best understood.

Why does zirconium tungstate act so counterintuitively, and, besides its undoubted interest as a curious and interesting phenomenon, what use is negative thermal expansion?

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