Raman spectroscopic study on the structure, phase transition and restoration of zirconium tungstate blocks synthesized with a CO2 laser
Raman spectroscopic study on the structure, phase transition and restoration of zirconium tungstate blocks synthesized with a CO2 laser
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DOI：
10.1002/jrs.1750
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发表时间：
2007-09
影响因子：
2.5
通讯作者：
E. Liang;S. H. Wang;T. Wu;M. Chao;B. Yuan;Wei Zhang
中科院分区：
文献类型：
--
作者：
E. Liang;S. H. Wang;T. Wu;M. Chao;B. Yuan;Wei Zhang
采用CO2激光快速凝固法合成了致密的钨酸锆块体。通过拉曼光谱和X射线衍射研究了样品的结构和相变性质。拉曼光谱研究表明，钨酸锆的固化具有正交结构。这归因于样品在快速凝固期间所遇到的压力。几个拉曼谱带在约390 K时不连续地变化，表明在该温度下发生了从γ相到α相的相变。在β相中，大多数拉曼模产生负的Gruneisen参数，表明相应的光学声子对材料的负热膨胀系数的贡献，至少对于β相。当样品冷却至室温时，观察到γ相的恢复。这表明立方结构仅在高于390 K的温度下是亚稳的，并且在室温下γ相是优选的。版权所有© 2007约翰威利父子有限公司。
Densely packed zirconium tungstate blocks were synthesized by rapid solidification with a CO2 laser. The structure and phase transition properties of the samples were studied by Raman spectroscopy and X-ray diffraction. Raman spectroscopic study reveals that zirconium tungstate solidifies with an orthorhombic structure. This is attributed to the pressure encountered by the samples during rapid solidification. Several Raman bands change discontinuously at about 390 K, indicating a phase transition from the γ- to the α-phase occurring at this temperature. In the β-phase, most of the Raman modes give rise to negative Gruneisen parameters, suggesting contribution of the corresponding optical phonons to the negative thermal expansion coefficient of the material, at least for the β-phase. A recovery of the γ-phase was observed when the samples were cooled to room temperature. This suggests that the cubic structure is metastable only at temperatures above 390 K, and at room temperature the γ-phase is preferred. Copyright © 2007 John Wiley & Sons, Ltd.