Journal of Advanced Ceramics ( IF 18.6 ) Pub Date : 2022-11-29 , DOI: 10.1007/s40145-022-0657-4
Shengjie Fan , Tingting Sun , Meng Jiang , Shijia Gu , Lianjun Wang , Haixue Yan , Wan Jiang
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As a high-temperature thermoelectric (TE) material, ZnO offers advantages of non-toxicity, chemical stability, and oxidation resistance, and shows considerable promise as a true ready-to-use module under air conditions. However, poor electrical conductivity and high thermal conductivity severely hinder its application. Carbon nanotubes (CNTs) are often used as a reinforcing phase in composites, but it is difficult to achieve uniform dispersion of CNTs due to van der Waals forces. Herein, we developed an effective in-situ growth strategy of homogeneous CNTs on ZnO nanoparticles by exploiting the chemical vapor deposition (CVD) technology, in order to improve their electrical conductivity and mechanical properties, as well as reducing the thermal conductivity. Meanwhile, magnetic nickel (Ni) nanoparticles are introduced as catalysts for promoting the formation of CNTs, which can also enhance the electrical and thermal transportation of ZnO matrices. Notably, the electrical conductivity of ZnO is significantly boosted from 26 to 79 S·cm−1 due to the formation of dense and uniform conductive CNT networks. The lattice thermal conductivity (κL) is obviously declined by the intensification of phonon scattering, resulting from the abundant grain boundaries and interfaces in ZnO-CNT composites. Importantly, the maximum dimensionless figure of merit (zT) of 0.04 at 800 K is obtained in 2.0% Ni-CNTs/ZnO, which is three times larger than that of CNTs/ZnO prepared by traditional ultrasonic method. In addition, the mechanical properties of composites including Vickers hardness (HV) and fracture toughness (KIC) are also reinforced. This work provides a valuable reference for dispersing nano-phases in TE materials to enhance both TE and mechanical properties.
中文翻译:
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在 ZnO 上原位生长碳纳米管以增强热电和机械性能
作为一种高温热电(TE)材料,ZnO具有无毒、化学稳定性和抗氧化性等优点,作为真正的空气条件下即用型模块具有广阔的前景。然而,较差的导电性和较高的导热性严重阻碍了其应用。碳纳米管(CNT)通常用作复合材料中的增强相,但由于范德华力,很难实现CNT的均匀分散。在此,我们利用化学气相沉积(CVD)技术开发了一种有效的在ZnO纳米粒子上均匀CNT的原位生长策略,以提高其导电性和机械性能,并降低热导率。同时,引入磁性镍(Ni)纳米粒子作为催化剂来促进CNT的形成,这也可以增强ZnO基体的电和热传输。值得注意的是,由于形成致密且均匀的导电CNT网络,ZnO的电导率从26 S·cm -1 显着提高到79 S·cm -1 。由于ZnO-CNT复合材料中丰富的晶界和界面,声子散射的加剧导致晶格热导率(κ L )明显下降。重要的是,2.0% Ni-CNTs/ZnO 在 800 K 时获得了 0.04 的最大无量纲品质因数 ( zT ),是传统超声法制备的 CNTs/ZnO 的三倍。此外,复合材料的机械性能包括维氏硬度(HV)和断裂韧性(KIC )也得到增强。这项工作为在TE材料中分散纳米相以提高TE和机械性能提供了有价值的参考。