ZrW_2O_8的负热膨胀特性表征

Characterization of negative thermal expansion property of ZrW_2O_8

以分析纯ZrO2和WO3为原料,采用分步固相法合成负热膨胀ZrW2O8粉体和陶瓷.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对产物结构及形貌进行表征,采用3种不同的方法测得ZrW2O8负热膨胀系数,研究了不同测量方法对ZrW2O8负热膨胀系数测量的影响.研究结果表明:合成的产物为单一的立方晶体结构的α-ZrW2O8,采用高温X射线衍射和PowerX软件测得样品从室温至600℃范围内的平均热膨胀系数为-5.605×10-6K-1;而采用热膨胀仪测得从室温至600℃范围内ZrW2O8陶瓷棒和冷压成型ZrW2O8粉体棒的平均热膨胀系数分别为-10.709×10-6K-1和-4.490×10-6K-1,测试方法、致密度和微观结构对样品的负热膨胀系数均有影响.

Negative thermal expansion （NTE） ZrW2O8 powder and ceramic were synthesized by solidstate reaction using analytically pure ZrO2 and WO3. The microstructures and section morphologies of the products were characterized by X -ray diffraction （XRD） and scanning electron microscope （SEM） re- spectively. The NTE coefficients of the samples were measured by three different methods. The effects of testing method on NTE coefficients were investigated. The results indicate that the resulting product is cubic ZrW2O8. The average thermal expansion coefficient of cubic ZrW2O8 is - 5. 605 × 10^-6 K-1 from room temperature to 600℃ obtained by high temperature X - ray diffraction measurement and Power X software ; and that of sintering ZrW2O8 ceramic rod is - 10. 709 × 10^-6 K^-1 and pressing ZrW2O8 powder rod is -4. 490 × 10^-6 K^-1, obtained by thermal dilatometer. The measuring method, density and microstructure all have effects on the measurement of NTE coefficient of the samples.