CO$lt;sub$gt;2$lt;/sub$gt;激光烧结合成负热膨胀材料Sc$lt;sub$gt;2$lt;/sub$gt;($lt;i$gt;M$lt;/i$gt;O$lt;sub$gt;4$lt;/sub$gt;)$lt;sub$gt;3$lt;/sub$gt;($lt;i$gt;M$lt;/i$gt;=W,Mo)及其拉曼光谱

用CO₂激光烧结合成了负热膨胀材料Sc₂(WO₄)₃和Sc₂(MoO₄)₃. 实验表明, 激光合成负热膨胀材料Sc₂(WO₄)₃和Sc₂(MoO₄)₃属于快速合成技术, 合成一个样品的时间仅需几秒到十几秒, 具有快速凝固的特征; X射线衍射和拉曼光谱分析表明, 所合成的材料为正交相结构, 且具有较高的纯度; 变温拉曼光谱分析表明, 所合成的材料在室温以上没有相变, 但可能有微弱的吸水性; 在对Sc₂O₃, MoO₃, WO₃, Sc₂(MoO₄)₃和Sc₂(WO₄)₃拉曼光谱分析的基础上, 给出了激光光子能量及原料和合成产物的声子能级图, 分析了激光烧结合成的机理. 激光光子能量转化为激发声子的能量是光热转化的主要通道, 原料在熔池中反应并快速凝固形成最终产物. 关键词： 负热膨胀材料 合成 激光烧结 拉曼光谱

Syntheses of negative thermal expansion materials Sc2(MO4)3 (M=W,Mo) with a CO2 laser and their Raman spectra

Negative thermal expansion materials Sc₂(MO₄)₃ (M={W}, Mo) are synthesized with a CO₂ laser. It is shown that the synthesis of Sc₂(WO₄)₃ or Sc₂(MoO₄)₃ by laser sintering is a rapid process so that a sample can be synthesized within a few or tens of seconds and has the characteristic of rapid solidification. X-ray diffraction and Raman spectrum analyses demonstrate that the synthesized Sc₂(MO₄)₃ (M={W}, Mo) are crystallized into orthorhombic structures and each have a high purity. Temperature dependent Raman spectrum analysis suggests that the synthesized samples do not have phase transitions above room temperature but possibly have weak hygroscopicities. According to the Raman analyses of MoO₃, WO₃, Sc₂(MoO₄)₃, and Sc₂(WO₄)₃, we draw a diagram describing their phonon energy levels and the photon energy of the laser, and then assess the mechanism of the synthesis by laser sintering. Transferring the laser photon energy to phonon energy is the channel of light-heat converting. The materials react in the molten pool and are solidified rapidly, forming the final products.
Keywords： negative thermal expansion material synthesis laser sintering Raman spectroscopy