BaTiO3/PVDF纳米复合介质的Maxwell-Wagner极化特性

Maxwell-Wagner Polarization Characteristics in BaTiO3/PVDF Nanocomposites

纳米复合材料具有成为高储能密度电介质的潜质,在脉冲和储能领域拥有巨大应用潜力,为此利用XRD、DSC和介电谱对BaTiO 3/α-PVDF、BaTiO 3/γ-PVDF复合介质的基体结晶情况和介电特性进行了分析。在室温0.1 Hz条件下,BaTiO 3体积分数为10%的BaTiO 3/α-PVDF介质相对介电常数为30,BaTiO 3体积分数为10%的BaTiO 3/γ-PVDF介质相对介电常数达52,γ相复合介质介电常数要越高于α复合介质,说明在低填充量下BaTiO 3/PVDF复合介质中基体晶形特性将对Maxwell-Wagner极化强度起主要作用,并利用一维结晶分布模型对复合介质中界面密度进行表征,结合复合介质损耗峰的位置,发现界面密度与Maxwell-Wagner界面极化松弛时间存在明显负相关性,为利用Maxwell-Wagner极化调节纳米复合电介质的低频介电特性提供了方法。

Nanocomposite has potential to become high energy density dielectrics, hence it has huge potential in impulse and energy storage fields. Consequently, we analyzed the crystalline behaviors and dielectric characteristics of BaTiO3/α–PVDF and BaTiO3/γ–PVDF nanocomposite matrices through XRD, DSC, and dielectric spectrum. The results showed that the permittivity of 10%BaTiO3/α–PVDF was 30;however, the permittivity of 10%BaTiO3/γ–PVDF was 52 at room temperature which was much higher than that of α phase nancomposites. The results also showed that, in low filler volume BaTiO3/PVDF composites, the crystalline properties played a main role in Maxwell-Wagner polarization intensity. Utilizing one-dimension crystal distribution model, we characterized the density of boundary in nanocomposites. According to the site of loss peak, we found there was negative relation between density of boundary in nanocomposites and Maxwell-Wagner polarization relaxation time. The conclusion can provide a method to control nanocomposites’ dielectric characteristics under low frequent using Maxwell-Wagner polarization.