本文采用固体草酸作沉淀剂,沉淀样品在水蒸汽气氛下焙烧分解,制成超微CuO、Y_2O_3和BaCO_3。用热分解法探讨其在水蒸汽下的分解机理,X射线衍射、红外光谱分析和元素分析对产物组成进行鉴定。通过电镜观察,超微粒子的粒径为:Y_2O_30.01～0.02μm、CuO0.02～0.03μm、BaCO_3～0.1μm。用空气吸附法测定其比表面积分别为146m~2g~(-1)、80m~2g~(-1)、20m~2g~(-1)。 In this paper, solid oxalic acid was used as precipitant, and the precipitated sample was roasted and decomposed under steam atmosphere to make ultra-fine CuO, Y_2O_3 and BaCO_3. The decomposition mechanism under water vapor was explored by thermal decomposition method, and the product composition was identified by X-ray diffraction, infrared spectroscopy and elemental analysis. Observed by electron microscopy, the particle size of ultrafine particles: Y_2O_30.01 ~ 0.02μm, CuO 0.02 ~ 0.03μm, BaCO_3 ~ 0.1μm. The specific surface area measured by air adsorption method was 146m ~ 2g ~ (-1), 80m ~ 2g ~ (-1) and 20m ~ 2g ~ (-1), respectively.