NaF-AlF_3二元系熔盐固相晶体与熔体结构的拉曼光谱及其计算模拟研究

Raman Spectroscopic and Theoretical Simulation Study on the Structure of Solid Crystals and Melts in Binary NaF-AlF_3 Molten Salt System

采用量子化学密度泛函计算方法对NaF-AlF3系熔盐的若干典型固相晶体结构进行了计算模拟拉曼光谱研究,并对光谱的振动形式进行了归属,发现特征峰位与铝配位数关系明显;同时,对NaF-AlF3二元系熔盐固相晶体及熔体结构进行了原位变温拉曼光谱实验研究。结果表明,基于计算模拟的振动谱峰归属分析,为NaF-AlF3系熔盐的微结构识别和温致结构变化提供了解析依据,而且随着AlF3浓度的增加,熔盐中铝六配位结构逐渐转化为铝四配位结构。

Density function theory （DFT） was applied to simulate Raman spectra of several typical solid crystals in binary NaF-AlF3 molten salt system. Those calculated vibrational modes of the spectra were assigned, and the characteristic peaks were related to the aluminum coordination number significantly. Temperature dependent structure of solid crystals and melts in binary NaF-AlFa molten salt system were recorded by in-situ high temperature Raman spectroscopic technique. The results demonstrateded that the attribution of vibrational modes based on computer simulation offered analytic basis for identification of microstructure and temperature induced structural changes of NaF-AlF3 molten salt system, and as the concentration of AlF3 increased, the configuration of six-coordination aluminum gradually transformed into four-coordination aluminum in the molten salt.