Abstract: Negative thermal expension ZrW 2 O8 powders were prepared by hydrothermal method , and influence of different acid solvents on the morphology was also studied .The precursors of ZrW 2 O8 were studied by Thermogravimetric and differential scanning calorimetry ( TG-DSC ) . The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction ( XRD) and Scanning electron microscopy (SEM), respectively.The results show that when the mixtures of HCl and HNO 3 are used,the pure ZrW2O8 powders with high crystallinity are obtained.With the amount of HNO3 increasing, particle size decreases ,and their morphology changes from rod-like to spherical shape .The results of in situ X-ray diffraction measurement indicate that the materials have strong negative thermal expension properties .

Key words: negative thermal expansion;ZrW2 O8;hydrothermal method