Tunable linear thermal expansion coefficient of amorphous zirconium tungstate

Zirconium tungstate (alpha-ZrW2O8) exhibits isotropic negative thermal expansion over a wide range of temperatures. Under high pressure it transforms to a metastable amorphous phase with positive thermal expansion coefficient. alpha-ZrW2O8 can be fully recovered by annealing the amorphous phase at temperatures slightly above 600 degrees C, at room pressure. In this work, we describe the dependency of the linear thermal expansion coefficient of amorphous ZrW2O8 with the annealing temperature, showing that it can be continuously tuned, in two stages, from about 7.5 degrees to -9 degrees C-1. These two stages are related to the relaxation of the amorphous phase and the onset of recrystallization, respectively.