本课题拟采用成熟的原位高压同步辐射X射线衍射、原位高压拉曼光谱和原位高压电学测量技术，研究纳米碱土金属氟化物(MF2，M= Ca, Sr, Ba)在尺寸效应下的高压结构相变及其电学性能的变化规律。通过多种原位高压实验结果的相互印证，获得不同晶粒尺寸纳米MF2的高压结构相变规律，确定其高压下纳米效应的临界尺寸，阐明尺寸效应对纳米MF2高压相变行为的作用机理，探索引起不同晶粒尺寸纳米MF2的高压相变行为差异的物理本质；获得高压下不同晶粒尺寸纳米MF2的电导率变化规律，揭示晶粒尺寸和晶体结构对其电导率的调制作用，明确不同压力区间电导率变化的影响机制。深入理解晶粒尺寸和晶体结构对纳米材料物理性能的重要影响，为新功能材料的可控制备提供全新的实验依据。

In this work, high-pressure phase transition and electrical characteristics for alkaline earth metal fluoride (MF2, M = Ca, Sr, Ba) will be studied in detail through in situ high-pressure techniques, which are exceedingly influenced by nano-size effect. The high-pressure phase transition of nano-MF2 with different grain sizes will be studied, including determining the critical dimensions of nano-MF2, which aroused in nano-size effect under high-pressure, clarifying the mechanism of nano-size effects for the high-pressure phase transition behavior of nano-MF2, exploring the physical nature of grain size on high-pressure phase transition behavior of nano-MF2.The conductivity variation of nano-MF2 under high pressure will be researched, which include revealing the modulation effect of grain size and crystal structure on electrical conductivity of MF2, clearing the mechanism of changes for electrical conductivity in different pressure range. From this work, we can deeply acquire the significant influence of grain size and crystal structure on the physical properties of nanomaterials, and it will provide a novel experimental approach for the controllable preparation of new functional materials.