Synthesis of hafnium tungstate by a CO2 laser and its microstructure and Raman spectroscopic study
Synthesis of hafnium tungstate by a CO2 laser and its microstructure and Raman spectroscopic study
复制标题
DOI：
10.1002/jrs.1929
复制
发表时间：
2008-07
影响因子：
2.5
通讯作者：
E. Liang;J. P. Wang;E. Xu;Z. Du;M. Chao
中科院分区：
文献类型：
--
作者：
E. Liang;J. P. Wang;E. Xu;Z. Du;M. Chao
采用CO2激光快速凝固法合成了致密的钨酸铪块体。结果表明，HfW_2O_8的最佳合成条件为激光功率700 W左右，扫描速度1 mm/s。扫描电子显微镜（SEM）观察表明，块体由定向的纳米线/棒组成，这些纳米线/棒在表面区域水平生长，在内部垂直生长。纳米结构的取向取决于表面和内部的传热方向。拉曼光谱和X射线衍射研究表明，样品以立方结构凝固，正交相含量较少。这是由于在快速凝固过程中由于熔池温度突然下降到环境温度而引起的压应力所解释的。通过与高压拉曼研究结果的比较，估算出应力约为0.6GPa。激光合成的样品中出现了一些特殊的拉曼谱带，而固相合成的样品中没有。版权所有© 2008约翰威利父子有限公司.
Densely packed hafnium tungstate blocks were synthesized by rapid solidification with a CO2 laser. It is shown that the optimum synthesis conditions for HfW2O8 are around 700 W laser power and 1 mm/s scan speed. Scanning electron microscopy (SEM) observation shows that the blocks consist of oriented nano-threads/rods that grew horizontally on the surface region and vertically in the interior. The orientations of the nanostructures are governed by the heat transfer directions on the surface and in the interior. Raman spectroscopic and X-ray diffraction studies show that the samples solidified in the cubic structure with minor contents of the orthorhombic phase. This is explained by a compressive stress induced during the rapid solidification process due to a sudden drop of temperature of the molten pool to the ambient. The stress is estimated to be about 0.6 GPa by comparison with high-pressure Raman study. Some specific Raman bands appear in the samples synthesized with the laser synthetic route but not in the sample by solid-state reaction. Copyright © 2008 John Wiley & Sons, Ltd.