Abstract Monoclinic K0.55WO3.275 has been synthesized by solid state reaction method. The space group is P2/m with cell parameters a = 15.9753(2) A, b = 7.73149(8) A, c = 10.9393(1) A and β = 108.477(1) ° at 313 K. The intrinsic linear coefficients of thermal expansion calculated by temperature-dependent X-ray diffraction data are 14.70 × 10−6 K−1 (253–323 K), 3.38 × 10−6 K−1 (323–363 K) and 11.52 × 10−6 K−1 (363–433 K), respectively, which are consistent with the apparent ones obtained by thermal dilatometer. The a axis shows positive thermal expansion from 253–433 K. The b and c axes display negative thermal expansion in the range of 323–363 K, and positive thermal expansion in two ranges of 253–323 K and 363–433 K. Three W–O–W bending modes with negative Gruneisen parameter may be responsible for the low thermal expansion in the range of 323–363 K.

中文翻译：

---

K0.55WO3.275 中的异常热膨胀

摘要 采用固相反应法合成了单斜晶K0.55WO3.275。空间群为 P2/m，单元参数为 a = 15.9753(2) A, b = 7.73149(8) A, c = 10.9393(1) A 和 β = 108.477(1) ° at 313 K。由温度相关 X 射线衍射数据计算的热膨胀为 14.70 × 10-6 K-1 (253-323 K)、3.38 × 10-6 K-1 (323-363 K) 和 11.52 × 10-6 K- 1 (363–433 K)，分别与热膨胀仪获得的表观一致。a 轴显示 253–433 K 的正热膨胀。 b 轴和 c 轴显示 323–363 K 范围内的负热膨胀，以及 253–323 K 和 363–433 K 两个范围内的正热膨胀。