Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。

Negative Thermal Expansion Property of Cr2(WO4)3 and Cr2(MoO4)3

Cr₂(WO₄)₃ and Cr₂(MoO₄)₃ powders were prepared by liquid phase reaction-precursor sintering method. in situ-powder X-ray diffraction data from 298 to 1 073 K shows an essentially linear increase in cell volume as a function of experimental temperature. The intrinsic linear coefficient of thermal expansion from these data is (1.274±0.003)×10^-6 K^-1 and (1.612±0.003)×10^-6 K^-1, respectively. Thermal expansion behavior of Cr₂(WO₄)₃ and Cr₂(MoO₄)₃ was studied in static air in the temperature range of 298 to 1 073 K by a thermo-dilatometer. Two samples showed a positive thermal expansion in the beginning, followed by a phase transition and then a negative thermal expansion (NTE). The negative thermal expansion coefficients (NTEC) of Cr₂(WO₄)₃ and Cr₂(MoO₄)₃ were (-7.033±0.014)×10^-6 K^-1 and (-9.282±0.019)×10^-6 K^-1, respectively.