柠檬酸溶胶-凝胶法合成负热膨胀性ZrW_2O_8粉体及其性质研究

Synthesis and property study on negative thermal expansion ZrW_2O_8 powders using the citric acid sol-gel method

以柠檬酸为螯合剂,采用溶胶G凝胶法制备负热膨胀性ZrW2O8粉体,对其前驱体进行热重G差热分析,以X射线粉末衍射、扫描电子显微镜对产物结构及形貌进行表征,结果表明所得粉体为单-α-ZrW2O8相,具有无规则形状.随着柠檬酸量的增加,颗粒有明显聚集长大的趋势,且形貌向片层状发展.变温X射线粉末衍射分析表明,所得ZrW2O8粉体具有很好的负热膨胀特性,在室温-500 ℃时,平均热膨胀系数为-6.14×10^-6/℃.

Negative thermal expansion( NTE) material Zr W2O8 powders were synthesized by the sol-gel method with citric acid used as chelating agent. The precursor of Zr W2O8 was studied by thermogravimetric and differential scanning calorimetry( TG-DSC). The structure and morphology of the resulting powders were characterized by powder X-ray diffraction( XRD) and scanning electron microscopy( SEM) respectively. The results showed that the samples were single phase of α-Zr W2O8 with irregular shape. With the increasing amount of citric acid,the particles grew bigger with a slice layer shape. The High temperature X-ray diffraction measurement indicated that the material had strong NTE. From room temperature to 500 ℃,the average thermal expansion coefficient was- 6. 14 × 10- 6/ ℃.