Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors

Science China Materials, May 2018

Monocrystal Sn nanorods encapsulated in the multi-walled carbon nanotubes (Sn@CNT NRs), were fabricated by a facile arc-discharge plasma process, using bulk Sn as the raw target and methane as the gaseous carbon source. The typical Sn@CNT NRs are 40–90 nm in diameter and 400–500 nm in length. The CNTs protect the inner Sn nanorods from oxidation. Temperature dependent I–V curve and electronic resistance reveal that the dielectric behavior of Sn@CNT NRs is attributed to the multi-wall CNTs shell and follows Mott-David variable range hopping [lnR(T)∝T−1/4] model above the superconducting critical temperature of 3.69 K, with semiconductor–superconductor transition (SST). Josephson junction of Sn/CNT/Sn layered structure is responsible for the superconducting behavior of Sn@CNT NRs.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1007%2Fs40843-018-9275-3.pdf

Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors

Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors Dongxing Wang 2 3 Da Li 1 3 Javid. Muhammad 2 3 Yuanliang Zhou 2 3 Xuefeng Zhang 0 3 Ziming Wang 2 3 Shanshan Lu 2 3 Xinglong Dong 2 3 Zhidong Zhang 1 3 0 Key Laboratory for Anisotropy and Texture of Materials (MoE), School of Materials and Engineering, Northeastern University , Shenyang 110819 , China 1 Shenyang National Laboratory for Materials Science, Institute of Metal Research, International Centre for Materials Physics, Chinese Academy of Sciences , Shenyang 110016 , China 2 Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education (MoE)), School of Materials Science and Engineering, Dalian University of Technology , Dalian 116024 , China 3 Electric transport of Monocrystal Sn nanorods encapsulated in the multi-walled carbon nanotubes (Sn@CNT NRs), were fabricated by a facile arc-discharge plasma process, using bulk Sn as the raw target and methane as the gaseous carbon source. The typical Sn@CNT NRs are 40-90 nm in diameter and 400-500 nm in length. The CNTs protect the inner Sn nanorods from oxidation. Temperature dependent I-V curve and electronic resistance reveal that the dielectric behavior of Sn@CNT NRs is attributed to the multi-wall CNTs shell and follows Mott-David variable range hopping [lnR(T)∝T−1/4] model above the superconducting critical temperature of 3.69 K, with semiconductor-superconductor transition (SST). Josephson junction of Sn/CNT/Sn layered structure is responsible for the superconducting behavior of Sn@CNT NRs. carbon nanotubes; nanocomposite; dielectric; variable range hopping; Josephson junction INTRODUCTION Encapsulation of nanostructured metals in graphite layers can protect the metallic core from oxidation. These carbon-coated nanostructures are now attracting more interest, due to their potential applications as functional materials such as lithium-ion batteries, fuel cell and electromagnetic wave absorbents [1–3]. The carbon shell encapsulating metallic core interferes in the electronic properties of the nanocapsules (NCs) through changing the ratio of sp2 to sp3 of the carbonaceous species. It is confirmed that the single-walled carbon nanotubes (SWCNTs) or their bundles show the classical transport properties such as Coulomb blockade, energy quantization, Luttinger liquid characteristics and ballistic transport [4,5]. It is usually difficult for the multi-walled carbon nanotubes (MWCNTs) to make electrical contact between neighbor graphite layers because the total conductance is significantly limited by the charge carrier transport [6]. Variable range hopping (VRH) conduction, weak localization, resonant tunneling phenomena, universal conductance fluctuations, or Aharanov-Bohm oscillations of magnetoresistance, may appear or become dominant in the electrical transport of MWCNTs-containing systems [7,8]. Sn is a typical metal with low melting point, high electrical conductivity, superconductivity, electrochemical activity and favorable behaviors. Bulk Sn has a relatively long coherence length of ξ(0) (200 nm) [9] at nanoscale. In the range of the coherence length (0–200 nm), the superconductive behaviors are expected to be significantly altered, for examples, a noticeable change in superconducting transition temperature (TC), decreased penetration depth, an enhancement in zero-field critical temperature, and finite residual resistance [10,11]. Coexistence of ferromagnetism and superconductivity was also found in Sn nanoparticles (NPs) with the size in range of 9–16 nm [12]. One-dimensional (1D) monocrystal Sn nanowires show TC close to 3.7 K; however both the electrical transport and the critical field are greatly size-related [13]. It has been reported that the superconductivity of carbon-coated Sn@C NCs will be destroyed as the size decreases down to 40 nm. However, it has also been demonstrated for the carbon-coated Sn nanorods with diameter of 50 nm and length of 200 nm, the critical magnetic field is almost 25 times higher than that of bulk Sn [14]. Large electrical current was also detected for MWCNTs encapsulated Sn nanowire, which can raise a local heating and in turn suppresses the superconductivity [15]. Electrical conduction in a nanocomposite consisting of the conductive and the insulative phases is usually attributed to electrical network and the percolation, in which the continuous conducting network or tunneling between isolated conducting particles would be concomitant [16]. A finite conductivity is ascribed to the inter-particles tunneling through the dielectric regime in the absence of metallic continuum. Kubo and co-workers [17] revealed that the energy gap between the nearest neighboring energy level increased rapidly with reducing the sizes of metal particles, and thus their physical properties differ from those of bulk metals. If the discrete gap becomes larger than the thermal energy kBT, a pronounced quantu (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1007%2Fs40843-018-9275-3.pdf

Dongxing Wang, Da Li, Javid. Muhammad, Yuanliang Zhou, Xuefeng Zhang, Ziming Wang, Shanshan Lu, Xinglong Dong, Zhidong Zhang. Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors, Science China Materials, 2018, pp. 1-9, DOI: 10.1007/s40843-018-9275-3