Thermo-Raman spectroscopic studies on polymorphism in Na2SO4
Thermo-Raman spectroscopic studies on polymorphism in Na2SO4
复制标题
Na2SO4 多态性的热拉曼光谱研究
DOI：
10.1088/0953-8984/12/5/315
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Hua Chang
中科院分区：
文献类型：
--
作者：
R. Murugan;A. Ghule;Hua Chang
以Na 2SO 4 10 H2O为起始原料，采用热拉曼光谱法（TRS），以1 °C为间隔，对Na 2SO 4和预干燥Na 2SO 4在从30 °C加热到500 ° C，然后冷却到30 °C的动态热过程中的相变进行了监测。的转换的基础上的频带的消失，出现新的频带，分裂的内部模式，在光谱分布的变化，强度（面积）的变化，在内部模式，全宽半最大值（FWHM）的完全对称的拉伸模式，甚至在热过程中观察到的背景中的变化。这种热拉曼研究提供了一些证据之间存在的中间相V相和I相，也为在较高的温度下观察到的I相结构的变化，除了众所周知的V相，I相，II相和III相之间的动态转换。对SO_4 ~（2-）3模的强度研究清楚地表明，在加热和冷却过程中，各相之间存在热滞后。本文还讨论了Na_2SO_4（以Na_2SO_4·10H_2O为原料）和预干燥Na_2SO_4在晶型上的差异。
The phase transformations involved in Na2 SO4 (Na2 SO4 10H2 O as starting material) and predried Na2 SO4 in a dynamic thermal process of heating from 30 to 500 °C and then cooling down to 30 °C, with a heating/cooling rate of 2 °C min-1 in two consecutive thermal cycles, were monitored at 1 °C intervals by thermo-Raman spectroscopy (TRS). The transformations were characterized on the basis of the disappearance of the bands, appearance of new bands, splitting in the internal modes, change in the spectral profile, intensity (area) changes in the internal modes, full width at half maximum (FWHM) of the totally symmetric stretching mode and even the variations observed in the background during the thermal process. This thermo-Raman investigation provided some evidence for the existence of an intermediate phase between phase V and phase I and also for the changes observed in the phase I structure at higher temperatures, in addition to the dynamic transformations between the well known phase V, phase I, phase II and phase III. The intensity study on the 3 mode of SO2- 4 clearly demonstrated the thermal hysteresis involved among the phases during the heating and cooling process. The differences observed in the polymorphisms of Na2 SO4 (Na2 SO4 10H2 O as starting material) and predried Na2 SO4 were also discussed.