Frequency‐Independent and Colossal Dielectric Permittivity of Platy Alumina/Few‐Layer Graphene Multilayered Composites

Bulletin of the Korean Chemical Society

Jaeyeol Hwang¹  SungMin Lee²  Dae Ho Yoon³  KiBeom Choi⁴ 

[1] Department of Advanced Materials Sciences and Engineering Sungkyunkwan University Suwon 16419 Korea;Department of Energy Science Sungkyunkwan University Suwon 16419 Korea;Department of Nano Applied Engineering Kangwon National University Chuncheon 24341 Korea;Icheon branch Korea Institute of Ceramic Engineering and Technology Icheon 17303 Korea

关键词: Permittivity;    Dielectric relaxation;    Platy alumina;    Graphene;    Composite;   

DOI  :  10.1002/bkcs.11405

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

In this work, we investigated the dielectric property of layer‐structured Al2O3/few‐layer graphene (FLG) composite by high temperature impedance spectroscopic analysis. The sintered composites have highly enhanced permittivity (ε = 17.3) compared to pure platy alumina (ε = 7.3) with low dielectric loss (tanδ ~ 10−3). Percolative permittivity of the composites exhibits almost frequency‐independent behavior at 1 Hz to 1 MHz even though the real permittivity was increased, compared to that of pure platy alumina. Such behavior can be explained by intervening dielectric interface between alumina and FLG based on multilayer filler model. After percolation threshold (FLG > 0.75 vol %), the permittivity is further enhanced up to ~260 (@1 kHz), which amounts to >35 fold increase, compared to pure platy alumina because of interfacial capacitance between FLG platelets and alumina. According to temperature‐dependent impedance analysis, a dielectric relaxation due to Al2O3/FLG interface is observed in the frequency range of 1 Hz to 1 kHz at high temperature (RT = 400°C) besides that due to Al2O3 grains (>10 MHz). Real permittivity increases up to >20 000 at 400°C at low frequency, whereas dielectric loss remains as tanδ ~ 3 × 10−4. High temperature impedance analysis shows that the effect of interface between Al2O3 and FLG is responsible for such dielectric relaxation at high temperature.

【 授权许可】

Unknown