Morphology-controlled synthesis of yttrium hafnate by oxalate co-precipitation method and the growth mechanism

Yttrium hafnate (Y2Hf2O7) precursor was prepared by mixing yttrium nitrate and hafnium (IV) chloride with ammonium oxalate aqueous solution. Yttrium hafnate powders with different morphologies were obtained by decomposition of the precipitate precursor at 800 °C for 4 h. The as-prepared particles were characterized by thermo gravimetric analysis (TGA), X-ray diffraction analysis (XRD) and field-emission scanning electron microscopy (FE-SEM). The concentration of the surfactant polyethylene glycol 6000 (PEG6000) was found to play a key role on the morphology of the particles. The possible mechanism of the morphology variation was proposed.