Ray Sekhar Chandra, Pao Chih-Wen, Tsai Huang-Ming, Chen Huang-Chin, Chen Yu-Shin, Wu Shang-Lun, Ling Dah-Chin, Lin I-Nan, Pong Way-Faung, Gupta Sanju, Giorcelli Mauro, Bianco Stefano, Musso Simone, Tagliaferro Alberto
Department of Physics, Tamkang University, Tamsui 251, Taiwan.
J Nanosci Nanotechnol. 2009 Dec;9(12):6799-805. doi: 10.1166/jnn.2009.1581.
This work elucidates the effects of high-temperature annealing on the microscopic and electronic structure of multiwalled carbon nanotubes (MWCNTs) using high-resolution transmission electron microscopy, micro-Raman spectroscopy, X-ray diffraction, X-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VBPES), respectively. The field emission and magnetization behaviors are also presented. The results of annealing are as follows: (1) MWCNTs tend to align in the form of small fringes along their length, promote graphitization and be stable in air, (2) XANES indicates an enhancement in oxygen content on the sample, implying that it can be adopted for sensing and storing oxygen gas, (3) the electron field emission current density (J) is enhanced and the turn-on electric field (E(TOE)) reduced, suggesting potential use in field emission displays and as electron sources in microwave tube amplifiers and (4) as-grown MWCNTs with embedded iron nanoparticles exhibits significantly higher coercivity approximately 750 Oe than its bulk counterpart (Fe(bulk) approximately 0.9 Oe), suggesting its potential use as low-dimensional high-density magnetic recording media.
本工作分别使用高分辨率透射电子显微镜、显微拉曼光谱、X射线衍射、X射线吸收近边结构（XANES）和价带光电子能谱（VBPES）阐明了高温退火对多壁碳纳米管（MWCNT）微观结构和电子结构的影响。还展示了场发射和磁化行为。退火结果如下：（1）多壁碳纳米管倾向于沿其长度以小条纹形式排列，促进石墨化并在空气中稳定，（2）XANES表明样品中氧含量增加，这意味着它可用于氧气传感和存储，（3）电子场发射电流密度（J）增加，开启电场（E(TOE)）降低，表明其在场发射显示器以及微波管放大器中的电子源方面具有潜在用途，（4）含有嵌入铁纳米颗粒的生长态多壁碳纳米管表现出约750奥斯特的矫顽力，明显高于其块状对应物（块状铁约0.9奥斯特），表明其作为低维高密度磁记录介质的潜在用途。
