Epsilon‐Negative Carbon Aerogels with State Transition from Dielectric to Degenerate Semiconductor,Advanced Electronic Materials

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Epsilon‐Negative Carbon Aerogels with State Transition from Dielectric to Degenerate Semiconductor
Advanced Electronic Materials ( IF 5.3 ) Pub Date : 2021-01-21 , DOI: 10.1002/aelm.202000877
Peitao Xie _{1,

2} , Wei Sun _{1,

3} , Ai Du ₁ , Qing Hou ₄ , Guangming Wu ₁ , Runhua Fan ₅

Affiliation

Aerogels with negative parameters have become a research hotspot since the discovery of negative Poisson's ratio and negative thermal expansion coefficient in aerogels. The negative parameters are originally brought up and studied in electromagnetic metamaterials, leaving a question that whether aerogels can be used to construct metamaterials with negative electromagnetic parameters. Here, the authors show that negative permittivity (epsilon‐negative) property can be achieved in carbon aerogels, and its value is adjusted continuously by changing the composition of carbon aerogels but keeping their microstructure unchanged. This is a novel strategy different from the typical array‐structure‐containing metamaterials. Moreover, a physical state transition is found when increasing the carbonization temperature, where the initial low‐loss dielectric state evolves into a high‐loss one upon increasing the temperature from 400 to 700 °C followed by a final degenerate semiconductor state when increasing the temperature to 800 °C and above. This work can provide a new method toward the design of electromagnetic metamaterials, starting by choosing the component materials with optimal composition.

中文翻译：

Epsilon负碳气凝胶，具有从介电到退化半导体的状态转换

自从发现负的泊松比和负的热膨胀系数以来，具有负参数的气凝胶就成为研究的热点。负参数最初是在电磁超常材料中提出和研究的，这就提出了一个问题，即气凝胶是否可用于构造具有负电磁参数的超常材料。在这里，作者表明，碳气凝胶可以实现负介电常数（ε负），并且通过改变碳气凝胶的组成但保持其微观结构不变，可以连续调节其值。这是一种新颖的策略，不同于典型的包含阵列结构的超材料。此外，当增加碳化温度时，会发现物理状态转变，当温度从400升高到700°C时，最初的低损耗电介质状态演变为高损耗，然后将温度提高到800°C及以上，则最终退化为半导体状态。这项工作可以为电磁超材料的设计提供一种新方法，首先是选择具有最佳成分的组成材料。

更新日期：2021-03-11

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