Development of low thermal expansion Sc2(WO4)3 containing composites

Negative thermal expansion (NTE) oxides are interesting materials for use in controlled thermal expansion composites. Since Sc-2(WO4)(3) shows stronger NTE (-11 x 10(-6)degrees C-1) behaviour between -263 and 927 degrees C compared with other NTE materials, this work develops low thermal expansion composites using ZrO2 or Cu as positive thermal expansion materials and Sc-2(WO4)(3) as NTE material respectively. Sc-2(WO4)(3) containing composites were synthesised using solid state method by co-sintering of Sc2O3, WO3 and ZrO2 mixture or Sc-2(WO4)(3) and Cu mixture with various ratios. The thermal expansion coefficient of the Sc-2(WO4)(3) containing composites can be controlled, being positive, negative or even zero. The Sc-2(WO4)(3)/ZrO2 and Sc-2(WO4)(3)/Cu composites show almost zero thermal expansion (0.3 x 10(-6) and 0.14 x 10(-6)degrees C-1) when the volume fraction of Sc-2(WO4)(3) is 25 and 70% respectively. The zero expansion of these composites allows them to be utilised as ceramic substrate of optical fibre gratings and some components in microelectronics to eliminate thermal stresses due to the thermal gradient or transient temperature change.