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Negative Thermal Expansion Materials

A major area of interest is in the field of negative thermal expansion (NTE) - that is materials which contract when heated. Cubic Zirconium Tungstate, for example, contracts continuously over a previously unprecedented temperature range of 2 to 1050K. Such materials have a range of potential engineering, photonic, electronic or structural applications. If, for example, one were to mix an NTE material with a "normal" material which expands on heating one could envisage making a zero expansion composite.

In addition to its negative thermal expansion, ZrW2O8 and related phases exhibit oxide ion mobility at remarkably low temperatures, unusual behaviour under applied pressure and unusual hysteresis effects.

Other materials such as A2M2O7 and A2(MO4)3 phases are also under investigation and show equally fascinating properties.

  • Flexible Frameworks can give rise to negative thermal expansion
  • ZrW2O8 - displays strong negative thermal expansion from 2 to 1400 K
  • ZrV2O7 - undergoes unusual structural phase transitions and negative thermal expansion at high temperature
  • A2(MO4)3 - phases show controllable negative thermal expansion
The cubic structure of ZrW2O8
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Modified 30-Jan-2011 by John S.O. Evans.