纳米离子导体在流体静压力下的复阻抗谱研究

 用惰性气体蒸发和真空原位加压方法制备了具有清洁界面的平均粒度16 nm的纳米固体CaF₂，并在0.1~2 400 MPa范围不同的静水压下用100 kHz~100 Hz内70种频率，精确测量了纳米CaF₂的复平面阻抗谱。分别给出纳米CaF₂离子电导率和相对介电常数随流体静压力的变化规律。最后的讨论指出：离子迁移通遭受压后的变化（大于、等于或小于最佳值）是影响离子电导率-压力曲线的主要因素；界面层空间电荷极化是造成纳米CaF₂相对介电常数较大的原因，由此界面效应可理解介电常数-压力曲线。

RESEARCH ON COMPLEX IMPEDANCE SPECTRAOF NANOPHASE IONIC CONDUCTORUNDER HYDROSTAIC PRESSURE

A nanophase soild CaF₂ which has clean interface and average graininess 16 nm was prepared with the method of evaporation in inert gas and being pressed in high vacuum, complex impedance spectra of nanophase CaF₂ were measured precisely using 70 frequencies from 100 kHz to 100 Hz under the different hydrostatic pressure from 0.1～2 400 MPa. Variations of both ionic conductivity and dielectric constant in nanophasc CaF₂ with pressure were given. It is indicated in final discussion that passage for migration of fluorine ions being compressed is the main factor of changing pressure-effect on ionic conductivity. Under low pressure the passage sizes much larger than optimum, so movement of F^- is not the fastest. Under 1 263 MPa pressure, the passage size reaches its optimum, migration of F^- is the easiest, hence σ reaches maximum. When pressure is over 1 263 MPa, the passage size becomes smaller and smaller than optimum, migration of F^- gets more and more difficult, so that σ diminishes rapidly. Besides, polarization of space charge on interface layer is the cause which makes relative dielectric constant of nanophase CaF₂ larger. From the role of interface we can understand the pressure effect of the dielectric constant.