Abstract Giant permittivity (GP) materials are of interest as possible capacitors for energy storage. Ferroelectric and related homogeneous materials suffer from strongly temperature dependent dielectric properties. Therefore, within the last two decades, the interest has been focused to dielectric studies of various inhomogeneous GP materials, where the essential role was shown to be due to weak but inhomogeneous conductivity. Here we study, within the known models based on effective medium approximation, the broadband dielectric spectra of conducting core – less conducting shell structures, which are expected to be the most advantageous for revealing the GP effects. Examples of core–shell structures, in which the dielectric properties of both components are independent of frequency, are studied analytically and numerically within the generalized brick model. For the simple case of coated-spheres model the dielectric dispersion is of a single Debye-relaxation type and the optimal GP properties are for highly conducting cores and thinnest possible nonconducting and high-permittivity shells. For non-spherical core–shell particles the conditions for macroscopically isotropic composite are briefly discussed.

中文翻译：

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介电光谱核壳结构模型的巨介电常数效应

摘要 巨介电常数 (GP) 材料作为可能的储能电容器受到关注。铁电材料和相关的均质材料具有强烈的温度依赖性介电特性。因此，在过去的二十年里，人们的兴趣一直集中在各种非均匀 GP 材料的介电研究上，其中的重要作用被证明是由于弱但不均匀的导电性。在这里，我们在基于有效介质近似的已知模型中研究了导电核 - 低导电壳结构的宽带介电光谱，这有望最有利于揭示 GP 效应。核壳结构的例子，其中两个组件的介电特性与频率无关，在广义砖模型中进行分析和数值研究。对于涂层球模型的简单情况，介电色散是单一德拜弛豫类型，最佳 GP 特性适用于高导电芯和尽可能薄的非导电和高介电常数壳。对于非球形核壳颗粒，简要讨论了宏观各向同性复合材料的条件。