Sub-micron spherical ZrO_2 particles were prepared by the solutions C_2H_5OH containing CO(NH_2)_2 and Zr(NO_3)_4·5H_2O via the solvothermal treatment at 100 ℃. Scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier transform infrared(FT-IR) spectroscopy, thermogravimetric and differential thermal analysis(TGA-DTA), and UV-vis spectra were used to characterize the samples. The influence of preparation conditions on the final product was investigated. The experimental results indicate that sub-mi...