金红石高温高压相变的Raman光谱特征  

Raman Characterization of Rutile Phase Transitions under High-Pressure and High-Temperature

作　　者：肖万生[1] 张红[1] 谭大勇[1] 翁克难[1] 李延春[2] 罗崇举[2] 刘景[2] 谢鸿森[3] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院高能物理研究所,北京100049 [3]中国科学院地球化学研究所,贵州贵阳550002

出　　处：《光谱学与光谱分析》2007年第7期1340-1343,共4页Spectroscopy and Spectral Analysis

基　　金：中国科学院知识创新工程方向项目(KJCX-SW-N20);国家自然科学基金项目(10299040)资助

摘　　要：以Ar作压力介质,在准静水压力条件下,利用激光加热DAC技术和显微Raman光谱原位测试技术,在0~35 GPa压力范围开展金红石的高温高压相变研究。在室温条件下,金红石结构TiO2于13.4 GPa开始转变成斜锆石相,于21 GPa时转变完全,并直到35 GPa时斜锆石相稳定存在。在压力分别为29.4和35.0 GPa时,用YAG激光器发出的波长为1.064μm的红外激光束扫描加热样品,TiO2斜锆石高压相转变成另一Pbca结构高压相。卸压时,Pbca相于26.3 GPa时转变成斜锆石相。斜锆石相转变成Pbca相需要加热才能发生,而卸压时却在较小的压力区间即迅速转变完全,两相转变压力边界在28 GPa左右。进一步卸压,斜锆石相直到11 GPa仍稳定,在7.6 GPa时斜锆石相与-αPbO2相两相共存,5 GPa时完全转变成-αPbO2相,并直到常压该相以亚稳定态存在。The pressure-induced phase transition of rutile-structured TiO2 was investigated by in-situ Raman spectrum method in a laser-heated diamond anvil cell （DAC）. The experiment was conducted at 35 GPa under quasihydrostatic conditions using argon as medium. At room temperature, the rutile-type TiO2 begins to transform to baddeleyite-type phase at 13.4 GPa and completes at 21 GPa, and this new high-pressure structure retains up to 35 GPa, the upmost pressure used in this study. At the pressure of 29.4 GPa the sample of baddeleyite-type TiO2 was heated by an YAG laser to about 1 000-1500 ℃ and then the baddeleyite phase transformed to a Pbca phase. The Pbca phase was heated again at 35.0 GPa and it was still stable. The sample then began to be decompressed, and the Pbca phase of TiO2 transformed to baddeleyite structure at 26.3 GPa, which stayed stable to 11.4 GPa. The formation of Pbca phase from baddeleyite phase needs the condition of high temperature, it transforms back to baddeleyite structure completely at pressure of a little below that on its formation, which suggests the boundary of the two phases can be determined at about 28 GPa. At 7.6 GPa, and the Raman spectrum shows the characteristics of the mixture of two phases of baddeleyite-type and a-PbOz-type, which indicates that the baddeleyite phase transforms to a-PbO2 phase at about 7 GPa. The α-PbO2-type TiO2 is metastable under ambient condition.

关 键 词：金红石 高温高压相变 Raman光谱 斜锆石相 Pbca相 α-PbO2相 

分 类 号：O433.4[机械工程—光学工程]