PDF(Pubmed)
Abstract：
The possibility of directly growing carbon nanofibers (CNFs) and carbon nanotubes (CNTs) on half-Heusler alloys by Chemical Vapour Deposition (CVD) is investigated for the first time, without using additional catalysts, since the half-Heusler alloys per se may function as catalytic substrates, according to the findings of the current study. As a carbon source, acetylene is used in the temperature range of 700-750 °C. The n-type half-Heusler compound Zr0.4Ti0.60.33Ni0.33Sn0.98Sb0.020.33 is utilized as the catalytic substrate. At first, a computational model is developed for the CVD reactor, aiming to optimize the experimental process design and setup. The experimental process conditions are simulated to investigate the reactive species concentrations within the reactor chamber and the activation of certain reactions. SEM analysis confirms the growth of CNFs with diameters ranging from 450 nm to 1 μm. Raman spectroscopy implies that the formed carbon structures resemble CNFs rather than CNTs, and that amorphous carbon also co-exists in the deposited samples. From the characterization results, it may be concluded that a short reaction time and a low acetylene flow rate lead to the formation of a uniform CNF coating on the surface of half-Heusler alloys. The purpose of depositing carbon nanostructures onto half-Heusler alloys is to improve the current transfer, generated from these thermoelectric compounds, by forming a conductive coating on their surface.
摘要：
首次研究了通过化学气相沉积（CVD）在半Heusler合金上直接生长碳纳米纤维（CNFs）和碳纳米管（CNTs）的可能性，不使用额外的催化剂，由于半赫斯勒合金本身可以用作催化底物，根据目前研究的结果。作为碳源,乙炔在700-750°C的温度范围内使用。n型半Heusler化合物Zr0.4Ti0.60.33Ni0.33Sn0.98Sb0.020.33用作催化底物。起初,建立了CVD反应器的计算模型，旨在优化实验过程设计和设置。模拟实验过程条件，以研究反应室内的反应性物种浓度和某些反应的活化。SEM分析证实了直径为450nm至1μm的CNF的生长。拉曼光谱表明，形成的碳结构类似于CNFs而不是CNT，并且无定形碳也共存于沉积的样品中。从表征结果来看，可以得出结论，短的反应时间和低的乙炔流速导致在半Heusler合金表面上形成均匀的CNF涂层。将碳纳米结构沉积到半Heusler合金上的目的是改善电流传输，从这些热电化合物中产生的，通过在它们的表面上形成导电涂层。
