石墨C—C键的温度、压力效应及键长的Raman频率表征

The Effect of the Temperature and the Pressure on Graphite C—C Bond and the Expression of C—C bond Length by Raman Frequency

本文在20℃～550℃,0GPa～13GPa压力区间内测量了石墨的Raman光谱,并在20℃～1100℃温度范围内做了石墨的X光衍射实验。实验结果表明,TG64型石墨在20℃～750℃温度范围内C-C键长随温度升高而收缩,温度高于750℃时键长随温度升高而膨胀。高压Raman的结果表明,石墨的E_(2q)活性模的频率随压力升高分段线性收缩,分段点在4GPa附近。同时还对在常温常压下利用Raman频率计算石墨C—C键长的Fitzer公式做了修正,并分别给出了温度和压力的修正因子以及C—C键力常数随温度、压力变化的规律。

Raman spectra of some graphite were measured in the pressure range from 0 GPa to 13 GPa and at temperature range from 20℃～55℃ and the experiment of Ⅹ-ray diffraction on the graphite was carried out in the range of 20℃～1000℃. It was observed in situ Ⅹ-ray experiment that with increasing temperature. The length of C-C bond of TG64 type grahpite contracted in the range of 20℃～750℃ and began to expand when temperature was higher than 750℃. The results of high pressure Raman show that the frequency of high pressure Raman active mode E_(2q) piecewise increases linearly with the increase in pressure, the piecewise point is at 4 GPa and the compressibility dv/dP below 4 GPa is bigger than that above 4 GPa. Fitzer's formula that is used to calculate the length of graphite's C-C bond by the Raman frequency of mode E_(2q) was corrected by using the factor of the temperature and the pressure respectively. The law of force constant which changes with the alter of the temperature and the pressure is expressed respectively.