Optimised Co-Precipitation synthesis condition for oxalate-derived zirconia nanoparticles

Zirconia (ZrO₂) nanoparticles were successfully synthesised from zirconyl chloride and ammonium oxalate via co-precipitation (CP), followed by calcination of the resulting co-precipitated precursor. CP and calcination processing parameters showed considerable effects on the surface morphology, average crystallite size, and phase purity of the resulting ZrO₂ particles. In this work, field emission scanning and transmission electron microscopy (FESEM and TEM) confirmed the existence of spherical and uniformly shaped ZrO₂ particles, with crystallite size ranging between 6 and 35 nm. Pure ZrO₂ nanoparticles synthesised through calcination at 650 °C had a strained monoclinic phase structure. On the other hand, ZrO₂ particles prepared through calcination at 600 °C revealed presence of a transitional phase from tetragonal to monoclinic phase in its X-ray diffraction (XRD) patterns. The FESEM images and XRD results also revealed that the degree of particle agglomeration and average crystallite size had increased with increasing processing temperatures and durations. Henceforth, precursor was co-precipitated at 40 °C for 1 h, then calcined at 650 °C for 4 h for optimum production of ZrO₂ nanoparticles with an average crystallite size of 12.85 nm and large Brunauer–Emmett–Teller (BET) surface area of 18.06 m²/g.