Abstract: ZrWMoO₈ powders with different morphologies were obtained by using ammonium tungstate, molybdate tungstate and zirconium tungstate as the starting materials by dehydration of the precursor ZrWMoO₇(OH)₂(H₂O)₂. The precursor was studied by thermogravimetric and differential scanning calorimetry(TG-DSC). X-ray powder diffraction(XRD), scanning electron micrograph(SEM) and X-ray fluorescence spectrometer(XRF) were used to study the influence of the varieties of the gelling agents on the crystallization process and crystal morphology of the resulted products. The results show that the kinds of gelling agent has a great influence on the morphologies of the resulted products, the thermal expansion coefficients of cubic ZrWMoO₈ prepared with HCl as the gelling agent is -3.84×10^-6 K^-1 from 100 ℃ to 700 ℃.

Key words: Negative thermal expansion, ZrWMoO₈, Dehydration of the precursor