氧缺陷钙钛矿在高温高压条件下的物性及其稳定性研究

钙钛矿是地幔的主要组成矿物，其物理化学性质和相变得到了广泛的研究。CaSiO3钙钛矿中的Si4＋离子能够被Al3＋离子取代而形成氧缺陷钙钛矿，如Ca2AlSiO5.5氧缺陷钙钛矿，这种替代会对钙钛矿的各种物理化学性质产生显著的影响。本项目将借助于同步辐射X射线衍射与金刚石压腔技术研究Ca2AlxSi2-xO6-0.5x氧缺陷钙钛矿的高温高压物理性质、稳定性、相变及相变产物。根据研究结果建立物性参数与氧缺陷浓度之间的量化关系、揭示氧缺陷钙钛矿的稳定性及相变机制和相变产物的成份与结构、对比纯钙钛矿和氧缺陷钙钛矿的物性特征及稳定性、进而探讨氧缺陷钙钛矿对地幔深部组成、结构、动力学和演化过程等的影响效应。

Perovskite, as the major component in the Earth's mantle, has been widely studied on its physical properties and phase transition. In CaSiO3 perovskite, the Si4+ can be substituted by Al3+, forming oxygen defect perovskite, e.g., Ca2AlSiO5.5. It is believed that such substitution can obviously change the physical and chemical properties of perovskite. In this proposal the physical properties, stabilities and phase transitions of oxygen defect Ca-perovskites Ca2AlxSi2-xO6-0.5x will be investigated by using diamond anvil cell combined with synchrotron radiative X-ray diffraction measurements. Based on the results, the quantitative relationships between oxygen concentration and physical properties will be established, the stabilities and phase transitions of oxygen defect Ca-perovskites will be clarified and compared with those of CaSiO3 perovskite. Further, the effects of oxygen defect Ca-perovskites on the component, structure, dynamicsand evolution of deep mantle will be discussed.