辉石中结构羟基变温行为的红外光谱初步研究

A preliminary FTIR study of structural hydroxyl in pyroxenes at varying temperatures

运用显微傅立叶变换红外光谱(Micro-FTIR)技术观察了辉石(单斜辉石和斜方辉石)中结构OH在原位连续加热、降温和阶段加热过程中的行为,从而更清楚地了解了缺陷氢在晶体结构中的位置及其结合机制。样品为安徽女山新生代玄武岩中的普通辉石巨晶和橄榄岩包体中的斜方辉石。温度从室温升到500℃,间隔100℃。实验结果表明,单斜辉石和斜方辉石的红外谱图随温度变化的趋势相同,即:OH的伸缩振动峰位都是随温度升高而向低波数移动,而且这种变化是可逆的;峰位的移动主要受H所取代的阳离子的位置或晶格空隙的热膨胀的影响。

The behavior of structural OH in clinopyroxene （Cpx） and orthopyroxene （Opx） during successive heating, cooling and stepped heating was investigated by in-situ Micro-FTIR measurements under temperatures ranging from 25℃ to 500℃at 100℃ increments. The results suggest that both Cpx and Opx exhibit a decrease in OH stretching vibration frequency with increasing temperature, and the variation is reversible. The shift in absorption band frequency is controlled by thermal expansivity of the OH site or lattice interstice.