纳米氧化铪粉体的制备及表征

Preparation and characterization of nano-hafnia powders

以由粗颗粒HfO2与NaOH化学反应制备并分离得到的HfOCl2为原料,分别选用分子量为400、1000和6000的聚乙二醇(PEG)(PEG400、PEG1000和PEG6000)作为分散剂,采用反向滴定化学沉淀法成功地制备出纳米级的氧化铪粉体。用X射线衍射分析(XRD)、透射电子显微镜(TEM)、扫描电镜(SEM)等手段研究结果表明:加入3种分散剂制备的粉体颗粒粒径均<50nm;用分子量较高的分散剂PEG6000所制得的粉体晶粒度更加细小;PEG6000的加入量在0.5%～2.5%质量分数范围内变化对最终的粉体晶粒度影响不大。用热重 差示扫描量热法(TG DSC)结合XRD对纳米HfO2粉体的研究结果表明:其晶型转变温度比微米HfO2材料降低了251℃左右(891～640℃);并且在焙烧温度>660℃时,生成了只有在高温高压条件下才能存在的斜方相HfO2。

Nano-HfO2 powder has been prepared successfully by reverse-titration precipitation method with HfOCl2 as raw material and PEG400, PEG1000 and PEG6000 as dispersant agent individually. The study results of X-ray diffraction (XRD), transmission electron microscope (TEM) and scanning electron microscope (SEM) show that the grain size with the three kinds of dispersant agents was smaller than 50 nm, but the grain size of those powders which used PEG6000 as dispersant agent smaller than that of the others; the variation on addition of PEG6000 from 0.5% to 2.5% doesn't affect the grain size of HfO2 powder evidently. The measuring results of TG-DSC and XRD on nano-HfO2 powders show that the phase transformation temperature of nano-HfO2 has decreased about 251°C (from 891°C to 640°C) as compared with micron-HfO2 materials. In addition, the experimental results indicate that when being calcined at general pressure and more than 660°C, the orthorhombic phase HfO2 which can only exist in high pressure and high temperature can be obtained.