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用二氧化碳激光快速凝固技术合成了负热膨胀材料钨酸钇。场发射扫描电子显微镜和X射线衍射分析表明:二氧化碳激光快速凝固技术合成的钨酸钇(Y2W3O12)为正交相的层状致密块体。Y2W3O12由于在大气中存放后会形成 Y2W3O12·xH2O, Raman光谱研究表明:其中的水分子不仅能阻碍其共享顶角多面体的摇摆,而且将阻碍每一种振动。低于388 K,所释放的水分子对[WO4]四面体内振动的影响较小,在该温度以上能够释放的水分子对 Y2W3O12框架结构中的多面体的摇摆运动、伸缩振动、弯曲振动、天平动和平动均有较大的阻碍作用。变温 Raman光谱揭示:不仅低频声子模,而且高频光学声子模对负热膨胀也有贡献。
The negative thermal expansion material yttrium tungstate was synthesized by the rapid solidification of carbon dioxide laser. Field emission scanning electron microscopy and X-ray diffraction analysis showed that the yttrium tungstate (Y2W3O12) synthesized by the rapid solidification of CO2 laser was a layered dense block with orthogonal phase. Since Y2W3O12 forms Y2W3O12 · xH2O when stored in the atmosphere, Raman spectroscopy studies show that the water molecules in it not only hinder its sharing of vertex polyhedrons but also hinder each kind of vibration. Below 388 K, the released water molecule has less influence on the vibration of the [WO4] tetrahedron. The water molecules released above this temperature have significant influence on the swing motion, stretching vibration, bending vibration, balance movement of the polyhedron in Y2W3O12 framework Peace move have a greater impediment. Variable temperature Raman spectroscopy reveals that not only low frequency phonon modes but also high frequency optical phonon modes contribute to negative thermal expansion.