Directed Synthesis of Ultradisperse Individual and Bimetallic Zirconium and Hafnium Oxides by Supercritical Antisolvent Precipitation

Abstract

A method for the synthesis of mono- and bimetallic zirconium and/or hafnium oxides by supercritical antisolvent precipitation has been developed. The oxides have been obtained using a laboratory dispersing system, alkoxides (zirconium propoxide, hafnium butoxide) and zirconium acetylacetonate have been used as precursors. A white powder of amorphous phase with composition MO2 · mH2O · nCxHyOz (M = Zr, Hf) has been obtained in all experiments. Differential thermal and X-ray powder diffraction analysis have been used to study the obtained phases and their thermolysis products (mono- and bimetallic zirconium and/or hafnium dioxides). Particle size and their morphology have been studied by optical and electron microscopy and dynamic light scattering. It has been shown that the particles of prepared oxides have spherical shape, while their size is dependent on the molar ratio of initial solution components. According to electron microscopy data, annealed samples have smaller particle size as compared with the initial samples.