We investigated two aspects of zirconium tungstate (ZrW
2O
8). First, we investigated the formation of ZrW
2O
8 in a sol-gel process that used tungsten (VI) chloride and zirconium chloride oxide 8-hydrate as raw materials, and ethanol and 2-butyl alcohol as solvents. Crystalline ZrW
2O
8 powder was obtained by heat treated between 600 and 777°C in air for one hour. ZrW
2O
8 ceramics could not be made using a conventional sintering process because the ZrW
2O
8 decomposition to WO
3 and ZrO
2 when it was heated to over 777°C. However, we made dense ZrW
2O
8 ceramics by heating ZrW
2O
8 amorphous powder at 600°C for 10 minutes by using spark plasma sintering.
Second, we used X-ray diffraction analysis and DSC to clarify how humidity affects the thermal expansion properties of ZrW208. Low density ZrW
2O
8 ceramics showed positive thermal expansion between room temperature and 120°C. On the other hand, high density ceramics showed negative thermal expansion between room temperature and 400°C. Both ZrW
2O
8 powder and lower density ceramic have H
2O either on or in their particles.
The H
2O prevented any other influence besides that of the thermal expansion property of ZrW
2O
8.
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