Influence of Consolidated Pressure upon Phase Transition and Ionic Conductivity of Nanophase PbF2
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摘要: 用惰性气体蒸发-真空原位固结法制备了直径为10 mm、厚度为1～2 mm的具有清洁界面的纳米PbF2块体材料，原位固结压强为0.3～1.8 GPa。采用X射线衍射和复阻抗谱方法，研究了固结压强对纳米PbF2物相组成、晶粒度和离子电导率的影响。结果表明，相同压强下，纳米-PbF2比粗晶-PbF2更易于向-PbF2转化；随着压强增大，样品中低电导率的-PbF2相不断增加，导致离子电导率下降。压强引起的连续相变使晶粒度缓慢长大。由于晶粒细小，纳米-PbF2的离子电导率比粗晶-PbF2提高约一个数量级，与粗晶-PbF2相当。Abstract: The bulk samples with a diameter of 10 mm and thickness of 1 to 2 mm of nanophase PbF2 were prepared by using an inert gas evaporation and in situ consolidating method under the pressure range from 0.3 GPa to 1.8 GPa. The average grain size and phase identification were studied by X-ray diffraction. The ionic conductivity was measured precisely by means of the complex impedance spectra. The results show that the phase content of -PbF2 enhances from 21.6% to 94.5% when the consolidated pressure increases from 0.3 GPa to 1.8 GPa. The ionic conductivity of nanophase PbF2 is about one order of magnitude higher than that of coarse-grain -PbF2, and is approximately equal to that of coarse-grain -PbF2.
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Key words:
- nanophase fluoride /
- consolidated pressure /
- phase transition /
- ionic conductivity
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