Ultrasound-assisted sol-gel synthesis of ZrO2

•The sol-gel synthesis of ZrO using Tween-20 leads to porous morphology.•Tetragonal ZrO2 was obtained using a low heat treatment temperature of powders.•The ultrasound-assisted sol-gel method demonstrated to take a lower reaction time. Synthesis of tetragonal ZrO2 by both conventional sol-gel and ultrasound-assisted sol-gel methods and using a non-ionic surfactant Tween-20, was performed. A porous microstructure composed of nanometric particles was observed. Tetragonal ZrO2 was obtained using a low heat treatment temperature of powders, 500°C by both methods. A higher crystallinity and a shorter reaction time were observed when ultrasound was used in the sol-gel method due to the cavitation phenomenon.