Unique Li_0.3Ti_0.02Ni_0.68O-carbon nanotube hybrids: Synthesis and their epoxy resin composites with remarkably higher dielectric constant and lower dielectric loss

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• 作者：Yifei Shen ; Guozheng Liang ; ^{lgzheng@suda.edu.cn" class="auth_mail} ; Li Yuan ; Zhixiang Qiang ; Aijuan Gu ; ^{ajgu@suda.edu.cn" class="auth_mail}
• 关键词：Composite materials ; Nanostructured materials ; Chemical synthesis ; Dielectric response
• 刊名：Journal of Alloys and Compounds
• 出版年：25 July, 2014
• 年：2014
• 卷：602
• 期：Complete
• 页码：16-25
• 全文大小：3864 K

文摘

Developing high-k (high dielectric constant) composites with simultaneously lower dielectric loss is an important subject of functional materials for actual cutting-edge applications. Novel hybrid (coded as LTNO-CNT) was synthesized by grafting nano-scale Li and Ti doped NiO (Li_0.3Ti_0.02Ni_0.68O, LTNO) onto the surface of carboxylated carbon nanotube (aCNT). The LTNO-CNT hybrids with different ratios of aCNT to LTNO were embedded in epoxy (EP) resin to prepare composites (LTNO-CNT/EP) with greatly increased dielectric constant and decreased dielectric loss. With the same loading of aCNTs (0.5 wt%), when the ratio of aCNT to LTNO was 1:1, the dielectric constant and loss at 100 Hz of the (LTNO-CNT)0.5/EP composite were 1.4 and 0.015 times the corresponding values of aCNT0.5/EP composite, respectively. While the dielectric constant and loss at 100 Hz of the composite with simple blends of LTNOs and aCNTs (LTNO/CNT0.5/EP) were severally about 0.36 and 0.12 times the values of the aCNT0.5/EP composite, meaning that the dielectric behavior of the LTNO-CNT/EP composite is not a simple additive property of those of LTNO/EP and aCNT/EP composites. This result is attributed to the special structure of the LTNO-CNT. Specifically, different from aCNTs, the LTNO-CNT hybrids have good dispersion in resin, forming many micro-capacitors, and thus leading to remarkably high dielectric constant. Meanwhile, LTNOs on the surfaces of aCNTs reduce the direct contact of aCNTs, resulting in greatly reduced dielectric loss. The aCNT/EP and LTNO-CNT/EP composites have different equivalent circuits, proving that the composites have different structures and thus significantly different dielectric behaviors.