Synthesis and negative thermal expansion property of Y_2?xLa_xW₃O₁₂ (0¡Üx¡Ü2)

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• 作者：Hongfei Liu^a ; ^{liuhf@yzu.edu.cn} ; Zhiping Zhang^b ; Wei Zhang^a ; Xianghua Zeng^a ; Xiaobing Chen^a
• 关键词：B. Composites ; C. Thermal expansion ; D. Ceramics  ; Tungstates
• 刊名：Ceramics International
• 出版年：2013
• 出版时间：April, 2013
• 年：2013
• 卷：39
• 期：3
• 页码：2781-2786
• 全文大小：1058 K

文摘

Y_2?xLa_xW₃O₁₂ solid solutions were successfully synthesized by the solid state reaction method. The microstructure, hygroscopicity and thermal expansion property of the resulting samples were investigated by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM) and thermal mechanical analysis (TMA). Results indicate that the structural phase transition of the Y_2?xLa_xW₃O₁₂ changes from orthorhombic to monoclinic with increasing substituted content of lanthanum. The pure phase can form for 0¡Üx¡Ü0.4 with orthorhombic structure and for 1.5¡Üx¡Ü2 with monoclinic one. High lanthanum content leads to a low relative density of Y_2?xLa_xW₃O₁₂ ceramic. Thermal expansion coefficients of the Y_2?xLa_xW₃O₁₂ (0¡Üx¡Ü2) ceramics also vary from ?9.59¡Á10^?6 K^?1 to 2.06¡Á10^?6 K^?1 with increasing substituted content of lanthanum. The obtained Y_0.25La_1.75W₃O₁₂ ceramic shows almost zero thermal expansion and its average linear thermal expansion coefficient is ?0.66¡Á10^?6 K^?1 from 103 ¡ãC to 700 ¡ãC.