目的 在无氢气沉积环境中研究CO2与CH4的流量比对金刚石膜生长及晶粒尺寸的影响规律。方法 采用MPCVD技术，通过调控CO2与CH4的流量比，可控性地制备得到不同结构特征的金刚石膜，通过SEM、XRD以及Raman光谱对金刚石膜进行表征分析，获得CO2与CH4的流量比对金刚石膜晶粒尺寸的影响规律。结果 在微波功率、沉积气压、基片温度和CH4流量分别为1.2 kW、7.0 kPa、850 ℃和50 mL/min的沉积环境下，当CO2流量为20和25 mL/min时，可制备得到纳米金刚石膜；当CO2流量为30和35 mL/min时，可制备得到微米金刚石膜；当CO2流量为67 mL/min时，可获得金刚石颗粒。在保持其他工艺条件不变时，通过调控微波功率分别为0.9、1.4和1.8 kW，金刚石膜的晶粒尺寸随CO2/CH4的变化可分为：纳米金刚石膜区（CO2/CH4<50%）、微米金刚石膜区（CO2/CH4>60%）及纳米-微米过渡区（50%

The work aims to study law of influence of CO2/CH4 flow ratio on growth of diamond films and grain size. The diamond films exhibiting different structural features were prepared controllably by adjusting the CO2/CH4 flow ratio and applying MPCVD technology. The diamond films were characterized and analyzed with scanning electron microscope, X-ray diffractometer and Raman spectrum, the rule of influence of CO2/CH4 flow ratio on grain size of diamond films was obtained. When microwave power, deposition pressure, substrate temperature and of CH4 flow was 1.2 kW, 7.0 kPa, 850 ℃ and 50 mL/min, respectively, nanocrystalline diamond films could be deposited using 20 and 25 mL/min CO2, microcrystalline diamond films could be obtained using 30 and 35 mL/min CO2, and diamond could be deposited using 67 mL/min CO2. By adjusting microwave power to 0.9, 1.4, 1.8 kW, respectively while keeping the other parameters constant, grain size variation of diamond films along with the CO2/CH4 flow ratio could be divide into three regions: nanocrystalline diamond film deposition region (CO2/CH4<50%), microcrystalline diamond film deposition region (CO2/CH4>60%), and grain size transition region (50%