EDTA assisted sol–gel synthesis of ZrW2O8

Abstract

A novel sol–gel synthetic route using water-soluble precursor salts is presented as a synthetic path for a high-purity negative thermal expansion material, ZrW2O8. This synthetic route involves a sol–gel method with the use of EDTA as complexing agent. The aqueous solution is transformed into a ceramic material after a two-step heat treatment: gelation at 60 °C and reactive sintering at 1,180 °C. The decomposition of the gel is monitored with infrared spectroscopy and TGA. The high-temperature heat treatment results in ZrW2O8 with its characteristic negative thermal expansion behaviour α[75–130 °C]: −9.8 ± 1.6 μm/m °C and α[175–300 °C]: −1.2 ± 0.2 μm/m °C.