高温高压下文石和方解石的拉曼光谱研究

利用金刚石压腔结合拉曼光谱分析技术，研究了文石在18～388 ℃，71～2 014 MPa，以及方解石在19～351 ℃，96～1 823 MPa条件下的拉曼光谱特征，并得到文石和方解石的拉曼位移与温度、 压力三者之间的关系式。研究结果表明，文石和方解石的拉曼位移随温度压力的变化规律相似，都随压力升高向高频移动，除文石的704 cm-1外均随温度升高向低频移动。二者的晶格振动ν_i/T值均大于[CO₃]基团内振动的值，说明CaO₆八面体的热膨胀性大于[CO₃]基团的热膨胀性。二者的对称伸缩振动ν/T及ν/P值不同，由于该振动拉曼位移和C—O键的键长有关，方解石的C—O键的热膨胀性比文石小而可压缩性比文石大。另外升温升压过程中文石和方解石可以相互转化，伴随该过程发生的[CO₃]基团旋转变形等动力学因素也可以造成二者ν_i/T和ν_i/P值差异。

Raman Spectra of Aragonite and Calcite at High Temperature and High Pressure

Raman spectra of aragonite and calcite were studied in the temperature range of 18～388 ℃ and pressure range of 79～2 014 MPa, and 19～351 ℃ and 96～1 823 MPa, respectively in the diamond anvil cell. The relationships among the Raman shifts of aragonite and calcite, the system pressure and temperature were obtained. The Raman shifts of aragonite and calcite become higher with the pressure increasing, and become lower with the temperature increasing except the Raman shift of 704 cm-1 of aragonite. The absolute values of ν_i/T of aragonite and calcite for the lattice modes are greater than those for the internal modes of the CO₃ groups, and the values of ν_i/T and ν_i/P of aragonite and calcite are various. The Raman shifts of the internal CO₃ modes are related to the C—O bond length and the C—O bond is more compressible and less expansible in calcite than in aragonite, besides, they may be also related to the dynamical effects of the CO₃ groups accompanying the aragonite-calcite transition.