The ZrO2 nano-powders were synthesized by a facile hydrothermal approach using ZrOCl2 ·8 H2 O as raw material,and the phase and microstructure of the as-synthesized ZrO2 were characterized by means of XRD and SEM.The effects of precipitant and hydrothermal temperature on the crystal phase of nano-zirconia were investigated in detail.The possible formation process of tetragonal zirconia nano-powders was also discussed.When ZrOCl2·8 H2 O reacted with the precipitant agent directly in the hydrothermal reaction...